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Calculators & tools

Commercial Kitchen Hood CFM Calculator

Estimate the exhaust airflow (CFM) for a wall-mounted canopy Type I hood, using IMC 507 minimum rates by cooking duty.
Planning estimate only — not a permit document. A licensed mechanical engineer sizes the real system per the IMC and your local authority.
3,000 CFM10 ft × 300 CFM/ft (medium-duty), wall-mounted canopy

The rates behind it

IMC 507 sets minimum exhaust for a wall-mounted canopy Type I hood by the duty of the heaviest appliance under it:

Cooking dutyCFM per linear footTypical equipment
Light200Ovens, steamers
Medium300Ranges, fryers, griddles
Heavy400Charbroilers, woks
Extra-heavy550Solid fuel (wood, charcoal)

Island, backshelf and eyebrow hoods use different (often higher) rates, and overhang, appliance mix and your AHJ can push the number up. You'll also need make-up air (commonly ~80–90% of exhaust). See the electrical requirements for hood interlocks, and what a hood is required over.

Frequently asked

How many CFM does a commercial kitchen hood need?
For a wall-mounted canopy Type I hood, the IMC minimum is roughly 200 CFM per linear foot of hood for light-duty equipment, 300 for medium-duty, 400 for heavy-duty (charbroilers, woks) and 550 for extra-heavy (solid fuel). Multiply the rate by your hood length. A 10-foot hood over fryers and griddles (medium-duty) needs about 3,000 CFM. Final sizing is set by a mechanical engineer per code and the hood manufacturer.
How do I calculate exhaust CFM for a range hood?
Take your hood's length in feet and multiply by the IMC exhaust rate for your heaviest cooking duty under that hood (200/300/400/550 CFM per foot for light/medium/heavy/extra-heavy on a wall canopy). The heaviest single appliance under the hood usually sets the duty class.
Do I need make-up air for a commercial hood?
Yes. Code requires replacing most of the air the hood exhausts with tempered make-up air (commonly around 80–90% of the exhaust volume), or the hood won't pull correctly and the building goes negative. Your mechanical designer sizes the make-up air unit alongside the exhaust.
Does this calculator meet code?
It's a planning estimate using IMC wall-canopy minimums. It is not a permit document. Actual requirements depend on hood style (wall vs island vs backshelf), overhang, appliance mix, and your local authority — a licensed mechanical engineer sizes and stamps the real system.