AHU Sizing Calculator
Static · formula-only · worked example computed when this page was built · no live data
The AHU Sizing Calculator finds the supply airflow, coil capacity, and fan motor for an air-handling unit from its cooling load. Example: for a 50 kW cooling load for a 300 m² space with 40 people, with a 10% design margin, at 24 °C indoor and 13 °C supply air, Supply airflow = 8325.1 CFM, Coil capacity = 30.39 TR, Fan motor = 11 kW (per ASHRAE 62.1 | ASHRAE 90.1 | ASHRAE 2021 Ch.1 | SMACNA).
How it works
Computed from your inputs per ASHRAE 62.1 | ASHRAE 90.1 | ASHRAE 2021 Ch.1 | SMACNA. Anything the worked example does not state uses this calculator's standard default; the interactive version shows every input and lets you change it.
Worked example (HVAC & Cooling)
Inputs: a 50 kW cooling load for a 300 m² space with 40 people, with a 10% design margin, at 24 °C indoor and 13 °C supply air.
| Result | Value |
|---|---|
| Supply airflow | 8325.1 CFM |
| Coil capacity | 30.39 TR |
| Fan motor | 11 kW |
Computed by WorkHive's calculation engine when this page was built; standard: ASHRAE 62.1 | ASHRAE 90.1 | ASHRAE 2021 Ch.1 | SMACNA.
How to use this calculator
- Read the worked example. It uses a 50 kW cooling load for a 300 m² space with 40 people, with a 10% design margin, at 24 °C indoor and 13 °C supply air and shows every number in the method.
- Follow the formula with your own figures: it returns Supply airflow, Coil capacity, Fan motor, computed per ASHRAE 62.1 | 90.1 | Fundamentals.
- To compute interactively, open the AHU Sizing Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is an air handling unit sizing calculator CFM?
The AHU Sizing Calculator is a free online tool that finds the supply airflow, coil capacity, and fan motor for an air-handling unit from its cooling load. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following ASHRAE 62.1 | 90.1 | Fundamentals. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive is free: this worked example is open to everyone, and the interactive calculator runs inside the free Engineering Design suite after a free sign-up (your work is saved to your account). WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive AHU Sizing Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.