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.