BrightHome buying guide · Updated November 6, 2026
How to match a replacement bulb base
Identify the fitting, then check the whole bulb.
Start with the old bulb
Before ordering a replacement, switch the light off and let the bulb cool. Read the printing on its base or glass and take a clear photo. Keep the fixture label in the same photo collection. A useful shopping note contains the base code, voltage, shape, maximum dimensions and any special fixture requirements. This takes a little longer than buying by appearance, but gives you something concrete to compare with a listing.
Separate shape from fitting
An A19 description refers to the bulb’s shape and size. E26 describes a medium screw base. A listing may include both because they answer different questions. E12 is a smaller screw fitting. GU10 is a twist-lock fitting, while GU5.3 uses two thin pins. A similar-looking spotlight can have a different base and electrical requirement. Match the printed specifications instead of assuming two spotlights are interchangeable.
Check the space around it
Measure the available height and width, especially inside a shade, recessed fitting or decorative globe. Include the space needed to install and remove the bulb. A replacement that screws in can still be too tall for its cover. For a multi-bulb fitting, make a note of how many bulbs you need and whether their visible shapes should match.
Before you buy
Compare the listing’s dimensions and voltage with your notes. Read the fixture instructions for enclosed use, location rating and dimming. If a socket is damaged or you cannot identify the electrical requirements, have the fixture assessed before choosing a replacement.
Reference for the specifications discussed above. Philips Hue fitting comparison