Duct size calculator uk You can enter the ducts starting from the fan and working down towards a selected terminal, with Duct Fitting Calculator you can calculate the pressure loss for more than 200 fittings as per ASHRAE standard. It is unnecessary to consider the duct material, length, or air volume since it is just a physical, geometric calculation. Explore the most-used forms and resources at Quietflex, including credit applications, installation instructions and the Ductulator. Try our user-friendly duct sizing tool today. It helps calculate the perfect balance between duct size, air velocity, and airflow, ensuring the HVAC system operates at peak efficiency. place on a ventilation duct run. Calculate your HVAC duct size in just a few easy steps. Ducts that are not well designed result in discomfort, high energy costs, bad air quality, and increased noise levels. This online ductulator calculates the dimensions for both round and rectangular duct options (one dimension should be Duct Size Calculator Get instant, accurate duct sizing calculations for your HVAC system. 1 inch/100ft. Open Calculator Need to find the right size? Our duct diameter calculator can help you work out the exact measurementsyou will need. Diameter converter, which converts circular diameters to equivalent rectangular ducts. 1° / - Module of imputation on the working sheet of the designation and the value of the K-factor. It accounts for both the straight sections of ductwork and the added resistance caused by bends or elbows, which reduce airflow efficiency. They use this knowledge to design and set up duct systems. Jun 9, 2023 · You will get the formula for calculating the duct heater sizing, what facts will affect them, and what to pay attention to when calculating. Conduit Calculator - Calculate the number of conductors to fit in conduit Duct Size Calculator - Calculate the number of conductors to fit in duct Utility - Calculates 3 phase current and horse power loads External Light Calc - Calculates luminescence for external lighting Lighting Level Calc - Calculates luminescence Free HVAC Duct Sizing - in SI/Metric or US/Imperial units. Green is generally within spec for Prihoda fabric ducts. 4 - free download- Duct Sizer calculates the friction loss in a section of duct, or calculates the duct size for a given friction loss. This varies with the system’s size. Equivalent rectangular size shown for a given flat oval size is the size of a rectangular duct that has the same friction loss per unit length as the flat oval. 16 Pa/m The S&P duct calculator allows three different calculations to be carried out quickly and with ease. Feb 27, 2025 · Master the essentials of duct size calculation to optimize HVAC performance and efficiency. Chilled Water Pipe Sizing Calculator The first and my favourite excel calculator is the chilled water pipe sizing calculator. These calculations are divided into four areas: 1. 3 days ago · Instant HVAC duct sizing calculator. Enter duct size, airflow, pressure, and other factors to calculate regenerated noise, breakout noise, and final noise levels after attenuation. Cable ducts are essential for organizing and protecting electrical cables in a wide range of environments, including commercial buildings, industrial settings, and residential projects. 1 kg/m to 160. Flexible Duct Size D/L [mm] D [mm] L [mm] Quantity [pcs] Flexible Duct Lateral Area / Free Area / Perimeter LArea[m²] FArea[m²] P [mm] Flexible Duct Options: Insulation Acoustic Insulation Note: A flexible duct, type spiral wire core helix, not completely stretched, is considered. The unit (like CFM) should match your project’s requirements. May 27, 2025 · The Exhaust Length Calculator is a practical engineering tool designed to determine the total effective length of an exhaust duct system. This calculator is invaluable for engineers and ductwork system designers. Further guidance can be found in the Excel Encyclopaedia. Fulfils tightness class C. The Duct Size Calculator is a quick reference tool for approximating duct sizes and equivalent sizes of sheet metal duct versus flexible duct. nethttp://www. You can let the program size all the ducts for you (using three different sizing methods), or enter your own sizes to analyze an existing design. Ductulator (HVAC Tools) Ductulator - Is a calculator used for sizing supply and retur duct systems using the equal friction design method. Special materials and sizes, please contact Lindab sales. You can use this page to calculate a quotation for a grille / diffuser, plenum box or ductwork. Non-insulated air ducts might weigh 6. Mar 26, 2024 · Smoke Extraction Fan CFM Calculation 1. Easy to use duct sizing toolSelect the duct material from the drop-down list (most duct sizing tools are typically based on galvanised steel ducting by default) Enter the air flowrate in litres/second (can change to cubic metres/second by use of drop-down to the right of the input) Enter an internal duct size (this must be limited to a maximum aspect ratio of 5:1 for the results to be valid Our equivalent size calculator takes out the pain of working out equivalent sizes of ductwork. Input your airflow rate, face velocity, and free area ratio to get accurate louvre sizes in both square feet and square meters. Calculate the correct duct size for your exhaust fan system. engineeringtoolbox. Increase efficiency and save on utlitiy bills. No matter how much money you spend on a high-quality HVAC system, the equipment won’t work at its best without properly designed and installed ductwork. 3. Ventilation parameter calculator allows the diameter, air speed, airflow and dynamic pressure of your installation to be calculated. If the selector turns red, your air velocity is May 28, 2025 · Duct Design Software: Employing sophisticated software applications can greatly enhance the design and evaluation of ventilation layouts. This calculator is commonly used by Jan 12, 2025 · Use Envigaurd's advanced duct size calculator online for free to accurately determine the right duct sizes for your HVAC system. Oct 3, 2024 · This is especially important in large buildings or specialized structures where improper duct sizing or weight estimations can lead to increased costs, installation issues, or even structural damage. Apr 11, 2025 · Easily estimate the noise levels generated by air moving through HVAC ducts using this Duct Noise Calculator. com cable sizing calculator. Your HVAC Solutions DeliveredHow to use? Select Duct Type: Choose the shape of your duct. It ensures the system is strong and efficient. Find the best duct dimensions for your HVAC system. Jul 15, 2018 · Duct sizing needs a ductulator or software but this excel calculator performs the same calculations. Jun 9, 2025 · Leave duct size calculations and installations to pros, but you can still use this duct sizing chart to understand the project better. Ensure these values are in the correct units (inches, cm, etc. Simply input the necessary dimensions, and the calculator will provide the total volume. Single-path units. Start typing numbers with "+" sign then press "Enter". By using BUSBAR Size Calculator we can prevent these issues by predicting them in the first place. Methodology: The Diffuser Size Calculator is a technical tool designed to assist engineers and HVAC professionals in calculating the appropriate size of diffusers for use in commercial and residential air distribution systems. Tested according to ISO 7235 standard. com/colebrook-equation-d_1031. Online calculator to compute friction loss in air ducts. This calculator is intended for use with all Quietflex flexible ducts. A properly Cable Calculator - Calculate cable sizes in minutes! All tables included. Perform quick calculation and accurate results. This spreadsheet program helps HVAC design engineers to perform all calculation needed for HVAC systems design including load estimation and all duct calculation. Quick, free and precise! Gram Clean Air Duct Calculator is a technical app developed to assist ventilation professionals with accurate calculations of pipe diameter, pressure loss, air velocity and airflow. Start typing numbers with "+" sign then Residential Air Duct Sizer and Velocity Calculator This ductulator calculates the exact duct size (round and rectangular) for the given friction rate, duct type, and amount of airflow. However, non-professionals can use the round duct friction loss chart to calculate the round duct size and then, convert it into rectangular duct size if needed. This article introduces a user-friendly Duct CFM Calculator that allows you to calculate airflow based on duct shape, size, and air velocity. View a demonstration. Our duct size calculator helps determine the appropriate duct diameter based on fan size and duct length. txt) or read online for free. These equations are useful for sizing and selecting ducts, as well as calculating the energy efficiency and operating costs of HVAC systems. Click the "Calculate" button for the results. CIBSE Duct Sizing V2. This versatile Louvre Sizer is perfect for residential, commercial, and industrial applications, ensuring optimal ventilation and climate control. Current carrying capacity and budget as under size busbar can cause heating and damage in busbar while over size busbar can affect the cost of project. HVAC ductwork equations are mathematical formulas that relate various parameters of duct design and performance, such as air flow, velocity, friction, pressure, and heat transfer. Duct sizing, Duct size, Static pressure. . A rough guide to maximum air volume capacity of circular ducts in comfort, industrial and high speed ventilation systems. The app is a simplest and quickest ductulator. If you know how much airflow (CFM) is going through a duct, you can use this to size rectangular or round duct based on a specific friction rate (rule of thumb is 0. KALK. LEV calculations Useful calculator for LEV assessors Contents Conversions Averages Volume flow Air change rate Air density Air velocity Conversions Duct Fitting Calculator is a powerful macro-enabled excel sheet that can perform pressure loss calculations for all types shapes of ducts and fittings in both I-P and SI units. Use h2x's free Duct Size Calculator to instantly calculate HVAC duct dimensions based on airflow, velocity, and shape. Efficiently design HVAC systems without cost. Minimum friction loss will only be obtained when the duct is properly installed. Air-handling units. The calculator assumes the duct is installed in the uncompressed condition. Calculate and compare HVAC duct sizes with our easy-to-use duct size calculator. Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator. in/wg Duct TEL : ft. Note: Linear pressure loss is based on an absolute roughness ε=2mm Note: Due to the compression of the wire The Ductwork Design Calculator is created to compute essential duct parameters for the efficient performance of duct systems. Among all the calculators, I use this calculator the most. Using our online calculator, you can determine essential parameters such as duct size, airflow rate, and ventilation area for your building projects. Our calculator supports both supply and exhaust design, allowing you to perform accurate calculations for ventilation ducts. The System Pressure Calculator helps you work out the resistance in pascals that elements such as spiral duct, bends, duct heaters etc. Calculate the ideal duct size for improved airflow and velocity. Calculator features: Automatic or manual input for air Duct type: Metal Ductboard Flex Size by: Friction rate Velocity Friction Rate: per 100 ft. 2°/ - Data Visualization Module of the pressure loss coefficients according to the duct shape. Openable model can be used as cleaning door for the duct system. That’s what this page is about – knowing the correct data to input into the Ductwork Calculator for air flow CFM, friction loss (which is loss due to friction) and the velocity the air needs to move. Fixed Bar Linear Grille Linear bar grilles are suitable for all supply or return sidewall/ceiling, floor, and sill applications. We would like to show you a description here but the site won’t allow us. It covers the factors that matter and the tools to get it right. The Duct Calculator helps HVAC contractors quickly determine the appropriate duct size based on airflow and velocity to ensure efficient system design and installation. Our duct size calculator simplifies your calculations. How To Calculate Duct Size Learn what duct sizing is, why it matters, how airflow is affected, and most importantly, how to calculate it quickly and accurately. Specify Air Flow: Enter the air flow rate. These programs utilize an air duct sizing calculator to provide detailed calculations and visual layouts, ensuring optimal system performance and efficiency. The Engineering ToolBox provides a wide range of free tools, calculators, and information resources aimed at engineers and designers. Use this free HVAC duct calculator to measure the area, velocity, equivalent length, and total pressure drop of your duct system. com Cable Sizing Software - select, size and manage your power cables using myCableEngineering. Enter design airflow (CFM). If the velocity selector is blue, you’ve arrived at a comfortable fabric duct selection. Optimise airflow and efficiency within your HVAC systems! The output includes the duct and fittings with their Descriptions and the SMACNA Fitting Code per the HVAC System Duct Design manual. This duct chart are based on equal friction method with a friction loss value = 0. This piece looks into how duct weight is calculated. What Changed So that we can focus all our efforts on our new application, we have retired our myElectrical. Flow Rates, Velocity, Pressure, Pipe Sizes. Basic Theory Duct Sizing Parameters Airflow (Q): The volume of air moving The program includes 2 procedures placed on customized command bar use to know the value of the coefficient K. Use the finger slide for quick calculations. Use any of the duct sizes shown. Metric or imperial! Free online ductulator for sizing of HVAC ducts. Duct Velocity Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator. Use our duct size calculator. Calculator of different ventilation parameters, with which will be able to obtain the diameter, the air speed, the airflow and the dynamic pressure of your Downspout & Gutter Sizing Calculator This app allows you to easily and accurately size downspout and gutters using the methods and formulas covered in SMACNA’s Architectural Sheet Metal Manual (ASMM). Diameter converter, which allows converting circular to equivalent rectangular ducts. Knowing the right weight lets us design, size, and reinforce systems well. Calculate duct dimensions for optimal HVAC performance. 1" wc / 100' of duct). Apr 6, 2025 · Duct Volume Calculator help you quickly and accurately calculate the volume of air ducts. html This calculator can also be used to simply convert round to rectangular or vice versa. Our calculator helps you determine the optimal duct dimensions based on airflow requirements and system specifications. HVAC Toolbox – Charts, Calculators, Cheat Sheets & Field References Welcome to the HVAC Toolbox — your one-stop reference hub for HVAC charts, calculators, cheat sheets, and design tools. Jun 6, 2020 · Download free duct sizing chart pdf according to ASHRAE standard. Designed to support both round and rectangular ducts, this tool simplifies airflow calculation without the need for manual formulas. Friction loss. Dual-Path Units. com? 1. Surface area is also computed to help estimate material requirements or Oct 1, 2024 · The Cable Duct Capacity Calculator helps determine the number of cables that can safely be installed within a cable duct. myCableEngineering. Cable Size Calculator for accurate current rating, voltage drop, short-circuit calculations complying with British Standard BS 7671 - 18th Edition. Includes scales for friction loss per unit length, air volume, air velocity, round duct diameter, and rectangular duct diameters. * include fittings in the Duct TEL Enter either: CFM: or Duct Size: CFM: Want to know how to use Ductulator. The flat oval shape Is specifically designed for low head room and restricted space locations which can't accept round duct. We recommend you now use our main cable sizing application over at myCableEngineering. Converts Duct Shape or Size to Another Determines Sizes for a Given Friction Rate Determines Sizes for a Given Velocity Determines Sizes for a Given Velocity and a Friction Loss Rate (simultaneous output) Learn how to calculate duct size effectively with h2x's comprehensive guide. Static pressure is an important parameter in air-moving systems as it helps determine how much resistance the air will encounter as it moves through ducts, filters, and other components. This tool is crucial for accurately sizing exhaust fans, maintaining airflow standards, and ensuring proper Jun 15, 2024 · In HVAC system design, ductwork weight is key. Let’s walk through this process, because Easily size ducts with our free online calculator. The S&P duct calculator allows three different calculations to be carried out quickly and with ease. ROUND DUCT SIZE ESTIMATE Round Metal Pipe Flex duct = . Output will be totaled for each section with all ducts and fitting losses and will display the Airflow Rate, Temperature, Density, Minimum Velocity, Duct Size, Actual Velocity, Duct Length, Loss Coefficients, and Air Duct Calculator Online calculator to compute friction loss in air ducts. Need to add up multiple airflow values? - Press enter after placing cursor in the CFM box. Jan 12, 2019 · HVAC excel sheet for all heating, ventilation and air conditioning calculation. Duct-U-Lator This app works as a Ductulator and Pressure Loss (friction) calculator which has the following functions. It will automatically adjust the size to keep from exceeding the maximum Manual D velocities for residential duct systems. PRO's duct calculator will help you estimate the required duct size of the ventilation system for quality air exchange in the room. Enter CFM and get accurate duct diameter — free tool for MEP engineers. Pressure drop Jul 17, 2024 · Ventilation Duct Size: Industry Standards and Best Practices When looking at ventilation duct sizes, it’s key to follow industry standards and best practices. Select the duct material from the drop-down list (most duct sizing tools are typically based on galvanised steel ducting by default) Enter the air flowrate in cubic feet per minute (CFM) Enter an internal duct size in inches (this must be limited to a maximum aspect ratio of 5:1 for the results to be valid) The resulting velocity and pressure drop per unit length are displayed in the blue box. 4. This balance is crucial for maintaining comfortable temperatures, adequate air quality, and minimizing Jun 12, 2025 · This calculator lets you determine the cross-sectional and surface areas of air ducts. To select the appropriate silencer and optimize connection size and length for the best performance you can use our online tool lindQST. It offers detailed technical data and calculations for various fields such as fluid mechanics, material properties, HVAC systems, electrical engineering, and more. 7 kg/m. 05" on most metal duct calculator Round metal pipe = . Transfer Grille Size Calculator - EfficientComfort. - Website will calculate total airflow and type it in the Airflow Quantity box. ). This might affect the input fields for dimensions. Oct 30, 2016 · Download McQuay DuctSizer Version 6. Apr 6, 2025 · Easily calculate HVAC duct size and estimate installation cost based on airflow requirements and duct dimensions. It includes sizing for metal ducts, and for flexible duct when compressed at 4%, 15%, and 30% straight line compression. Shows equivalent round and rectangular duct sizes. Enter duct sizing criteria: - Maximum air velocity - Maximum air pressure drop per 100 ft 2. Whether you’re in the field, estimating, or designing, this page gives you the essentials: sheet metal gages, duct sizing tables, airflow formulas, refrigerant data, and more. If desired, adjust duct size by clicking up or down arrow. Our online tool helps electricians, engineers and contractors calculate the right size conduit, fill percentages and jam probability per NEC guidelines. CIBSE have verified our easy-to-use design and calculation software. This Fee and Easy to Use Online Calculator allows users to properly size return air pass through diffuser sizes and transfer duct sizing. The equal friction method for sizing air ducts is easy and straightforward to use. Duct size chart calculate duct dimensions for both rectangular and round ducts. Jul 20, 2024 · Plenum Area Calculation: Area (m²) = Airflow (m³/s) ÷ Air Velocity (m/s) By using the plenum size calculator, plenum size calculations, plenum volume formula, and plenum area calculation, engineers and designers can find the right plenum size. Ducts that are too large Premium Online Ductulator App (Duct Size Calculator)Ductulator is an engineering tool to calculate air duct dimensions based on given inputs including air-flow, duct material roughness and either air pressure static loss (friction method) or air velocity (velocity method). Download also: HVAC Duct Size Calculator Excel Spiral Flat-Oval Duct Plat-oval spiral duct is machine formed round spiral duct. Ducts that are too small will cause air pressure to drop, reducing the system’s efficiency and effectiveness. Kitchen Range Hood calculator will help you estimate the exhaust ventilation capacity by kitchen size to remove heat, odors, moisture, and smoke. Proper duct sizing ensures optimal airflow, energy efficiency, and comfort within a building. Supports both metric and imperial units. All Duct Calculator - EfficientComfort. Optimize HVAC systems with our online duct sizing tool for accurate airflow and efficient design. Enhance your HVAC Feb 10, 2025 · Furthermore, utilizing an air duct size calculator can assist in calculating duct dimensions based on airflow rate and friction loss, ensuring accuracy in sizing. Nov 6, 2024 · Take out the guesswork of calculating the right duct size for your home. This tool is mainly used for sizing ductwork during the HVAC design for construction documents, but it doesn't end there. Free online ductulator for sizing of HVAC ducts. 06" on most metal duct calculators Mar 26, 2024 · So, how do you calculate the size of round ducts and rectangular ducts? Normally, engineers use simple software or a ductulator (provided by suppliers) to determine the size of a duct. Air Flow, Equipment Selection, Components and Assemblies ACCA Manual T ACCA Manual S Duct Size Calculation ACCA Manual D Adjust, Test, Balance ACCA Residential Duct Diagnostic & Repair EQUIVALENT LENGTHS Quickly determine the ideal louvre dimensions for your HVAC system with our Louvre Size Calculator. Jul 31, 2024 · Use our ductwork sizing and cost calculator to get the right duct size for your HVAC system. Some useful calculators for LEV surveyors. Ductsize - HVAC Duct Sizing and Analysis Duct Sizing - with Full Control Ductsize lets you create a complete duct system from start to finish, and gives you control over every aspect of the design. Free for MEP engineers and draftsmen. Designed for fast and accurate dimensioning, this app makes it easier to work with complex aspects of process ventilation. HVAC Resources for Professionals Enter and adjust the parameters in the blue boxes. VAV Systems. An HVAC Duct Sizing Calculator is a tool that helps you determine the correct size for the ducts in your heating, ventilation, and air conditioning (HVAC) system. Use it for rectangular or round ducts, depending on your HVAC layout. HVAC – HOW TO SIZE AND DESIGN DUCTS Air flow problems have plagued the HVAC industry for years. Duct Sizer The Duct Sizer is a productivity app . xls), PDF File (. Our simple spreadsheet configurator will help to guide you with regards to calculating your containment sizing requirements. 1. With this tool, you can determine optimal duct sizes, calculate air velocity, and assess pressure drops along various duct segments. Need to add up multiple airflow values? - Press enter after placing cursor in the Airflow Quantity box. These calculations are divided in four areas: 1. pdf), Text File (. Mar 25, 2024 · The ductulator calculator is a specialized tool used in the HVAC industry to determine the most efficient duct sizes for air distribution within a space. Insulated Use h2x's free Air Duct Velocity Calculator to instantly calculate airflow speed and ductwork area. This ensures the hvac plenum design meets airflow needs and boosts energy efficiency. What is the purpose of this calculator? This calculator helps determine the area of a duct based on its size, useful in HVAC and duct design. 16 Pa/m Use our free online Ductulator to calculate velocity, pressure drop, Reynolds number, and friction factor based on duct type, flow rate, and air properties. One side uses I-P units, the other side uses SI units. Note: Linear pressure loss is based on an absolute roughness ε=2mm Note: Due to the compression of the wire Flexible Duct Size D/L [mm] D [mm] L [mm] Quantity [pcs] Flexible Duct Lateral Area / Free Area / Perimeter LArea[m²] FArea[m²] P [mm] Flexible Duct Options: Insulation Acoustic Insulation Note: A flexible duct, type spiral wire core helix, not completely stretched, is considered. Dual-Duct VAV Systems Feb 19, 2024 · In this article, we you will find HVAC duct size charts that provide guidelines for selecting the appropriate duct size for the airflow of your system. Includes airflow, velocity, and size reference. Use our free duct sizer calculator to determine optimal duct dimensions for efficient air flow in HVAC systems, minimizing pressure drop and friction loss. For installation instructions refer to the duct package. Learn from Case Studies: Correctly sizing ducts is vital for preventing AC problems and extending the unit’s lifespan by reducing wear and tear. net Cable Calculator - Calculate cable sizes in minutes! All tables included. It’s really been helping me to quickly find the corresponding chilled water pipe size based on the water flow rate. Enter the information in the Blue boxes Answers are given in the Green boxes Velocity: 8 m/s Duct Diameter (mm): Duct Diameter: 315 mm Calculated Duct Diameter: 315 mm Calculated Resistance: 0. Or you can do any combination of the two, where you Jul 31, 2024 · Use our ductwork sizing and cost calculator to get the right duct size for your HVAC system. xls - Free download as Excel Spreadsheet (. Input dimensions in inches, centimeters, or millimeters, and get the area in square inches, cm², ft², or m². In the UK, knowing the what size are standard ducts uk? question is vital for experts and installers. Optimize airflow, reduce energy costs, and enhance system efficiency with precise calculations tailored for commercial, industrial, and pharmaceutical applications. well-designed ductwork A rough guide to maximum air volume capacity of circular ducts in comfort, industrial and high speed ventilation systems. Choosing the correct duct size ensures the cables have adequate space, preventing Jun 3, 2025 · Our Ductwork Calculator, which some call a ductulator, gives accurate results for duct sizing diameter when the right information is plugged into it. The tool calculates the optimal diffuser size, taking into account factors such as air velocity, throw distance, static pressure, and air pattern dispersion. 2. Compatible with IP and SI units. Conduit Calculator - Calculate the number of conductors to fit in conduit Duct Size Calculator - Calculate the number of conductors to fit in duct Utility - Calculates 3 phase current and horse power loads External Light Calc - Calculates luminescence for external lighting Lighting Level Calc - Calculates luminescence Standard size of circular ventilation air ducts. com. Download HVAC duct size chart PDF for rectangular and round ducts. Nov 12, 2024 · The CFM to Static Pressure calculator is a tool used to estimate the static pressure (SP) in an HVAC system or ventilation ductwork based on the airflow rate (CFM). Enter Dimensions: Input the dimensions of your duct based on the type selected. Bookmark it and come back Introduction: CFM Duct Size Calculator for Round and Rectangular Ducts In HVAC system design, proper duct sizing is essential to ensure efficient airflow, optimal comfort, and system performance. The straight sections of the long sides are stretched taut and perfectly flat. All Calculators Trending now Ductulator Duct Size Calculator **NEW** Interpolation Perform a linear interpolation calculation given two know points on a line and an additional x or y coordinate Select the duct material from the drop-down list (most duct sizing tools are typically based on galvanised steel ducting by default) Enter the air flowrate in litres/second (can change to cubic metres/second by use of drop-down to the right of the input) Enter an internal duct diameter (this can be any number, it doesn’t need to be standard duct size) To get an idea of the equivalent A duct size calculator, commonly known as a ductulator, depends on factors like the size of the space you’re heating or cooling, air flow velocity, friction loss, and available static pressure of the HVAC system. Velocity (m/s - Meters per Second): Velocity: 8 m/s Duct Diameter (mm): Duct Diameter: 315 mm Calculated Duct Diameter: 315 mm Calculated Resistance: 0. Excel Containment Sizing Calculator Containment sizes may be calculated based on the: dimensions of the containment, diameter of the cable and fill ratios. Home / Air Flow Calculator Air flow calculator For a quick duct size check, why not try our calculator? Choose the duct shape, then use the sliders to find the fabric duct size or air volume you need. nwv bfwaz cfcrfls rpqnntpv yvvv cohezold ulvfghmz lwnfoa nfxwu jaantyjt zmuiu rkbi ils cdug goigou