How to calculate kitchen extraction rate: a complete sizing guide

An undersized kitchen extraction hood turns a kitchen into a sauna: stagnant steam, condensation dripping from the ceiling, grease building up on the walls, and a fire risk that climbs every year. An oversized hood, on the other hand, wastes hundreds of euros every month sucking heat out of the room. Correct sizing is the difference between a workable kitchen and one that ages prematurely. Here is the method used by professional kitchen consultants across Europe.

The base rule: extraction rate in m³/h per m² of covered surface. For standard hot cooking (range, fryer, plancha), plan 800 m³/h per m² of hood. For intensive cooking with pizza oven or wok, push to 1,200-1,500 m³/h/m². For neutral zones (prep, dishwashing), 400 m³/h/m² is enough. A 2 m × 1 m hood above a range needs at least 800 × 2 = 1,600 m³/h.

Exact calculation formula (per French DTU 68.3 and CIBSE TM50): Rate = Hood area (m²) × Capture height (m) × Air speed (m/s) × 3,600. Air speed must reach 0.3 m/s at the bottom edge of the hood to capture vapours effectively. Concrete example: a 1.2 × 0.9 m hood placed 1.2 m above the range → 1.2 × 0.9 × 1.2 × 0.3 × 3,600 ≈ 1,400 m³/h. This is the MINIMUM rate; add 20 % to absorb peak service.

Wall-mounted or island hood? A wall-mounted hood (three sides closed) is more efficient: it captures 100 % of the flow because the side walls channel the vapours. An island hood (four sides open) needs +30 % rate to compensate dispersion (more noise, higher consumption). Pick an island only when the layout demands it (range in the middle of the room). See our range of professional kitchen hoods to compare wall vs island models.

Filters: stainless baffle or activated carbon? Baffle filters (stainless steel) are essential — they trap 70-90 % of grease via centrifugal effect, are dishwasher-safe and last 10+ years. Activated carbon is only needed in recirculation hoods (no outside duct) — it neutralises odours but must be replaced every 6 months (~80 € per filter). In a pro kitchen with outside venting, forget activated carbon: redundant and expensive.

Installation and regulation. The hood must overhang the hot cooking zone by at least 15 cm on every side. Height between heat source and bottom of hood: 70 cm minimum, 1.1 m maximum (beyond this the capture rate collapses). Outside duct in stainless steel 304 mandatory (grease is flammable), minimum 200 mm diameter for 1,500 m³/h. Access hatches every 3 metres or at every elbow. Compliant with EN 13779 + local fire-safety regulations for hospitality venues.

Budget and running cost. Plan 1,500-3,000 € HT for a 1,200 mm wall hood with built-in motor, 2,500-5,000 € HT for a 2,000 mm high-capacity unit, 4,000-8,000 € HT for a 2 m × 1 m island hood. Add 800-1,500 € for a remote motor (recommended to cut noise in the kitchen). Ductwork + installation runs 1,500 to 4,000 € depending on length and elbow count. Running cost: an 800 W motor running 10 h/day ≈ 600 €/year of electricity.

Common mistakes to avoid. (1) Hood too small: the steam clouds the chef's eyes and reaches the dining room. (2) Filters never cleaned: built-up grease = hood-fire risk (the #1 cause of kitchen fires). (3) No make-up air: the hood pulls air but the room goes into negative pressure, doors slam and draughts cool the plates. (4) PVC ducting: banned (flammable grease) — always stainless steel. To validate your project, contact us via the contact page with your kitchen dimensions and cooking equipment list.