What size range hood do you need? Answer in 30 seconds — no guesswork, no greasy cabinets.
Tip: after your first result, every tweak updates live — try heavy cooking or a bigger kitchen.
Not sure where to start? Try a scenario:
Gas: total BTU ÷ 100. Electric / induction: cooktop width (in) × 10. This matches hood power to heat and steam output.
Kitchen volume (cu ft) ÷ 4 — sized to refresh the room's air about 15 times an hour while you cook.
Heavy frying, wok, or searing adds a ×1.5 bump. The result is rounded up to the nearest 50 CFM, like real hood sizes.
Divide the total BTU output of all burners by 100. A 60,000 BTU cooktop needs about 600 CFM. Heavy frying or wok cooking? Size up one step.
Multiply the cooktop width in inches by 10. A 30-inch electric or induction cooktop needs about 300 CFM.
At least as wide as your cooktop — ideally 3 inches wider on each side so it captures everything. A 30-inch cooktop pairs well with a 36-inch hood.
Generally yes for hoods over 400 CFM — most building codes (IRC) require a makeup-air system so your home doesn't go negative pressure. Check local code.
Up to 400 CFM: 6-inch round. 400–750 CFM: 8-inch. 750–1200 CFM: 10-inch. Above that: 12-inch or talk to a pro. Bigger is quieter — never downsize the duct below the hood's outlet.
400 CFM suits many light-to-moderate setups, but a typical 60,000 BTU gas cooktop calls for about 600 CFM by the BTU ÷ 100 rule. Frequent frying, searing, or wok cooking usually needs more.
Not always. Oversizing can add noise, cost, and makeup-air requirements without improving capture if the hood is too small or mounted too high. Match CFM to your cooktop, use a hood at least 3 inches wider than the cooktop, and size the duct correctly.