Ventilation Rate Calculator — Extract Rates per Document F
Calculate required extract ventilation rates for kitchens, bathrooms, WCs and habitable rooms per UK Building Regulations Approved Document F (2021).
Internal room length
Internal room width
Floor to ceiling height
How We Calculate This
This calculator determines the required ventilation rates for individual rooms based on UK Building Regulations Approved Document F (2021 edition). It covers both intermittent extract rates and whole-dwelling continuous ventilation.
Intermittent extract rates (ADF 2021 Table 5.1a)
- Kitchen: 30 l/s adjacent to hob (ducted cooker hood over hob), 60 l/s elsewhere (no hood or recirculating), 13 l/s continuous
- Bathroom / shower room: 15 l/s
- WC / cloakroom: 6 l/s
- Utility room: 30 l/s
- Habitable rooms: No extract required (trickle vents only)
Whole dwelling continuous rates (ADF 2021 Table 5.1b)
- 1 bedroom: 19 l/s
- 2 bedrooms: 25 l/s
- 3 bedrooms: 31 l/s
- 4 bedrooms: 37 l/s
- 5+ bedrooms: 43 l/s
- Or 0.3 l/s per m² of floor area (whichever is higher)
Trickle vent equivalent areas
- Habitable rooms: 8000 mm²
- Wet rooms: 4000 mm²
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates. Verify with your supplier.