English edition
Choose the right bulb, with numbers
Our French site has helped readers choose bulbs room by room since 2020. This English edition keeps only the guides built on hard data and adapts them to the UK (230 V, B22 bayonet, BS 7671) and the US (120 V, E26, NEC).
Start here
Bulb basesB22, E26, E27, E14, GU10, MR16: identify yours in 10 seconds.
Lumens vs wattsOfficial equivalence tables (UK/EU and US).
How much light per roomLux, foot-candles and the lumen formula, worked out.
Colour temperature2700K, 3000K, 4000K, 5000K: which room gets which.
CRIWhy CRI 90 matters in kitchens and bathrooms.
IP ratingsUK bathroom zones and US damp/wet locations.
Dimmable LEDsLeading vs trailing edge, minimum load, flicker.
Replace halogen spotsGU10 and MR16 to LED, with the transformer trap.
UK and US: the three differences that cause wrong purchases
| United Kingdom | United States | |
|---|---|---|
| Mains voltage | 230 V, 50 Hz | 120 V, 60 Hz |
| Most common screw/bayonet base | B22 bayonet (BC), then E27 (ES) and E14 (SES) | E26 (medium), E12 (candelabra), E17 |
| Efficiency label | UK energy label A–G (rescaled in 2021) | Lighting Facts label (FTC), ENERGY STAR certification |
| Wiring rules | BS 7671 (IET Wiring Regulations), Part P in England and Wales | National Electrical Code (NEC), local permits |
GU10 spotlights exist in both 230 V and 120 V versions with the same base: always check the voltage printed on the bulb.
How we work
No page without data. Figures come from regulations (EU/UK ecodesign, ENERGY STAR, IEC 60529, BS 7671, NEC) or from manufacturer specifications, and every calculation is shown. Product links are Amazon affiliate links (UK and US); they never change our verdicts. See our affiliate disclosure.