What size bulb does a wax warmer take?

This is the error that sends people back to the shop. "25 W wax warmer bulb" is not a specification - it is half of one. Wattage tells you how much power the bulb will draw; the base tells you whether it physically fits and makes contact.

Buying a 25 W bulb with the wrong base is the single most common reason a working warmer looks broken. So is buying a bulb of the right base and a higher wattage than the warmer is rated for, which is a genuinely bad idea rather than merely a wasted trip - the housing and the wiring were designed for a specific maximum.

1. Unplug the warmer and let it cool completely. Warmer bulbs run hot and the housing holds heat after the bulb goes off.
2. Look for a label on the base or underside. Most warmers carry a printed rating - voltage, frequency and maximum wattage. The Candle Warmers Etc. models we index print theirs as 120 V, 60 Hz and a wattage.
3. Take the old bulb out and look at the base. A screw base with a narrow thread is candelabra-style; a two-pin push-and-twist base is a GU-type. If there is any printing on the bulb itself, that is your answer.
4. Check the maker's own designation. Candle Warmers Etc. names its bulbs by code - NP1 in the Milk Glass lamp, NP3 in the Vintage Bulb Illumination warmer. If your warmer is from a brand that does this, buy by the code.
5. If nothing is printed anywhere, photograph the base and measure it. Base diameter is the deciding dimension, and a bulb listing will state it.

Note the last row, because it is a legitimate way to opt out of this problem entirely. An electric dish warmer has no bulb. If you have already been through one round of hunting a replacement, that is a good reason to make your next warmer a plate one - see our wax melt warmer picks.

Bulbs are cheap individually and are almost always sold in multipacks, which changes how you should think about it: the cost is not the bulb, it is that a warmer you cannot source a bulb for becomes an ornament.

Two of the lamps we index ship with a spare in the box, which is a real convenience and buys you time to identify the fitting before you need it. Take the spare out and look at it on the day the warmer arrives rather than in eighteen months when the first one goes.

The full running-cost picture, including how bulb replacement compares with the electricity, is on bulb replacement costs.

Generally no, and it is worth understanding why rather than just being told.

In a bulb-heated warmer the bulb is not the light source with heat as a side effect - the heat is the function. An incandescent or halogen bulb converts most of its power to heat, which is exactly what melts the wax. An LED of the same nominal wattage produces a fraction of that heat, because being efficient at making light instead of heat is the entire point of an LED.

Fit an LED to a bulb warmer and you will typically get a well-lit warmer that never melts anything. If low running cost is what attracted you to the idea, the honest answer is a low-wattage plate warmer rather than an LED in a bulb warmer.