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CFM / AHU Airflow Calculator — ACH, Sensible Load & Duct Velocity
Calculate airflow from room volume and chosen ACH, sensible cooling load and temperature difference, or measured average duct velocity.
ELECTRICAL TOPICCFM / AHU Airflow Calculator
Your result
AIRFLOW CALCULATIONREADY
—Enter values below and press Calculate.
RESULT DISPLAYVolume / heat → CFM
Calculation details & exports
Inputs used
ElectricalTopic.com Tools© 2026 ElectricalTopic.comVolume / heat → CFMFormula and worked example
ACH method: CMH = room volume_m³ × ACH; CFM = CMH / 1.69901079552. Sensible method: m³/s = sensible kW / (ρ × cp_kJ/kgK × ΔT). Total-load input: sensible kW = total TR × 3.516853 × SHR. Duct method: m³/s = inside area_m² × average velocity_m/s.
Worked example
A 10 × 6 × 3 m room at an entered 6 ACH gives 180 m³ × 6 = 1,080 m³/hour = 635.664 CFM. In sensible-load mode, 10 kW, ΔT = 10°C, air density 1.2 kg/m³ and cp = 1.005 kJ/kg·K give 1,756.9486 CFM. These are chosen example assumptions.
Using this tool
Enter the actual equipment and project values. The Use example button loads an illustrative case. Calculation happens in your browser; no Python, API key or account is required. Use the result details to see the inputs and scope, copy the result, download CSV or print.
AHU की total supply air और outdoor fresh air अलग हो सकती हैं। हर TR पर 400 CFM को fixed rule न मानें; sensible load, SHR, ΔT और actual air properties के अनुसार flow बदलता है।
Common questions
Is 400 CFM per TR always correct?
No. Total TR includes sensible and latent cooling. Airflow from the dry-bulb temperature equation requires sensible load, air properties and the selected temperature difference.
Does room ACH certify required fresh air?
No. Entered ACH is a design target. Total recirculated supply, outdoor air and clean-air delivery are different quantities; occupancy and applicable ventilation requirements need separate assessment.
Does this select an AHU or fan?
It calculates airflow. Coil latent performance, filtration, outside-air mixing, fan static pressure, acoustics and actual AHU/fan selection remain separate.
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Formula references and model scope
Formula review: 2 November 2026. Examples are illustrative. Enter project-specific data; a planning result does not certify an installation or equipment selection.
