Lighting · Explainer · 4 min ·
A bulb can be the right brightness and the right colour and still be useless, because it will not fit the lamp. The part that decides is the cap, the short code like E27 or GU10 printed on the bulb.
Pick a socket and a bulb and watch them slide together or stay apart, then type in a measurement to find your own cap. Learn what the letters and numbers mean, how to read or measure what you have, which cap shows up in which lamp, and what else to check once it fits.
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A plain warm-white LED spot for GU10 spotlights and downlights. Check the cap in your fitting first, since GU10 pins twist-lock and nothing else fits.
GU10 cap · Warm white · 4.3 W · LED spot
A two-pack of glass filament-style bulbs for E27 lamps, good for bare-bulb or open shades. Check the bulb's width against your shade before you buy.
E27 cap · Warm white · 4 W · Filament style
A smart candle bulb for small E14 sockets, where the warmth can be changed from an app. Only worth it if you want that control and your lamp has an E14 socket.
E14 cap · Candle shape · Tunable white · Smart
