MBE / HUB-Certified Texas MEP

Restaurant Exhaust CFM Estimator

Most TX permit second-rounds on restaurant fit-outs trace back to one of three things: undersized exhaust, missing make-up air, or a hood/duty mismatch. This calculator gives you the IMC 507.13.1 prescriptive minimum in under a minute — pick hood type, duty, and length, and you’ll see what reviewers expect to see on your drawings.


Most common in QSR build-outs; mounted against a wall over the cookline.


If your line mixes duties, code requires you to use the highest duty present.


Use the actual hood overall length, not just the cookline length.

Prescriptive minimum exhaust
3,000CFM
Basis: Wall canopy, medium duty, 10 ft × 300 CFM/ft

Code minimum only. Final design must consider make-up air, hood overhang,
capture velocity, appliance manufacturer data, and AHJ interpretation.

2–6 weeks

Typical permit-cycle delay we see when restaurant exhaust isn’t sized to IMC 507.13.1 the first time. Pyra Engineering is currently surveying 100+ Texas GCs and architects on what actually breaks tenant fit-out MEP schedules.
See the open survey →

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Pyra Engineering is an MBE/HUB-certified Texas MEP firm. Stamped drawings for restaurant fit-outs across TX and FL — quote in 1 business day, permit-ready package, single point of contact.

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Reference: IMC 507.13.1 prescriptive CFM/ft

Values below are CFM per linear foot of hood, by hood type and cooking duty, per the International Mechanical Code Table 507.13.1. N/A means that hood style is not approved for that duty without performance-based design.

Hood type Light Medium Heavy Extra-heavy
Wall-mounted canopy 200 300 400 550
Single-island canopy 400 500 600 700
Double-island (per side) 250 300 400 500
Eyebrow 250 250 N/A N/A
Backshelf / pass-over 250 300 400 N/A
Important. This estimator returns the prescriptive code minimum. It does not account for make-up air balancing, hood overhang, side-panel adjustments, capture-and-containment performance testing, or AHJ-specific amendments. Permit submittal requires sealed drawings from a licensed engineer in the project’s jurisdiction.
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Estimator v0.2 · IMC 507.13.1 prescriptive method