By Emmanuel Sauvage · Updated
Tutorial
How much light per room (lux and foot-candles)
Lux (lx) = lumens per square metre. Foot-candles (fc) = lumens per square foot. 1 fc = 10.764 lx.
Recommended levels
Ranges below follow the work-surface values of EN 12464-1 (used by CIBSE in the UK) and the residential ranges of the IES (Illuminating Engineering Society, US) handbook, rounded.
| Space | Lux | Foot-candles |
|---|---|---|
| Hallway, stairs | 100–150 | 10–15 |
| Living room (ambient) | 100–200 | 10–20 |
| Bedroom (ambient) | 100–150 | 10–15 |
| Kitchen (general) | 200–300 | 20–30 |
| Kitchen worktop, reading, desk | 500 | 50 |
| Bathroom mirror | 300–500 | 30–50 |
| Workshop bench | 500–750 | 50–75 |
The formula
Lumens needed = target lux × floor area (m²) ÷ utilisation factor.
US: lumens needed = target foot-candles × floor area (ft²) ÷ utilisation factor.
The utilisation factor (0.5–0.6 in a typical home with light walls) accounts for light absorbed by walls, ceiling and shades. Use 0.5 for dark décor or shaded fittings.
Worked example (UK, metric)
Kitchen 3 × 4 m = 12 m², target 300 lx general: 300 × 12 ÷ 0.55 = 6,545 lm. With 350 lm GU10 LEDs, that is 6,545 ÷ 350 ≈ 19 spots, or fewer spots plus under-cabinet strips to reach 500 lx on the worktop.
Worked example (US, imperial)
Living room 14 × 16 ft = 224 ft², target 15 fc ambient: 15 × 224 ÷ 0.55 = 6,109 lm. With 800 lm A19 bulbs (60 W equivalent), that is ≈ 8 bulbs spread over ceiling and lamps.
Check the result
A free smartphone light-meter app gives a rough lux reading (±10–20 % depending on the phone). Measure at worktop or table height, lights on, curtains closed.
UK · GU10 230 V
Philips LED Classic GU10 4.6W, 4000K (6-pack)
Listing: 50 W equivalent, 390 lm, CRI 80, 220–240 V, non-dimmable, energy class F.
Check price on Amazon UKUS · E26 120 V
Philips Ultra Definition LED A19, 8W, 2700K (8-pack)
Listing: 60 W equivalent, 800 lm, E26 base, dimmable, flicker-free. Listed as CRI 95.
Check price on Amazon USProduct data below is taken from the manufacturer's listing on Amazon, checked on 22 October 2026. Prices change: check the current price before buying. As an Amazon Associate I earn from qualifying purchases.