Lighting · Explainer · 4 min ·
Why does a lamp flicker, hum or refuse to dim when you turn the dimmer down? Two things have to match: the bulb must say dimmable, and the dimmer must suit low-power LEDs.
Try four bulb and dimmer pairings with a dial, see what flicker looks like, why half the dial isn't half the brightness, and what to check on the bulbs you already own before buying anything.
You turn a dimmer down, and the lamp starts to flicker, hum or just stays stubbornly bright. Nothing is "broken": the bulb and the dimmer simply don't speak the same language. The good news is that dimming is one of the cheapest ways to make a room feel calmer, and a few labels tell you whether it will work.
Evening light that is lower and warmer tells your body the day is winding down, and it makes a room look softer. A dimmer lets one lamp do the job of several: bright enough to read at 7 pm, low enough to sit with a book or a conversation at 10 pm. You don't need more lamps for that, only lamps you can turn down.
A dimmer works by cutting up the electricity many times a second so the bulb gets less of it. An old-style bulb with a glowing wire didn't care how it was fed. An LED bulb has a tiny electronic power supply inside, and that supply has to be built to cope with the chopped-up current. So there are two checks:
Try the four combinations below. Slide the dial and watch what each pairing does.
Your eyes adjust to the dark, so a lamp turned down to half its light output still looks much brighter than half. The practical result: a lot of the cosy-feeling range is in the lower part of the dial, and a bulb that is smooth there is worth more than one that is bright at the top. It's also why a bulb that cuts out or flickers near the bottom feels so annoying: that is exactly where you want to be in the evening.
Cosy is not about buying more, so start with what you own. Pick up each bulb in the lamps you dim and read the base or box. If it says dimmable, you may be fine already. If the lamp has its own turning knob or a cable switch, that is a dimmer too, and it may suit LEDs better than an old wall one.
Next, look at the lamp itself: the cap type (E27 is the large screw, E14 the small one), the maximum wattage printed near the socket, and how much space the shade leaves. Measure the shade opening against the bulb's diameter, because some rounded bulbs are wider than the classic pear shape and won't fit under a narrow shade.
If your wall dimmer is the old kind and the lights flicker, swapping a wall dimmer is a job for a qualified electrician, not a weekend experiment. A plug-in lamp dimmer or a smart bulb avoids touching the mains wiring at all.
If your bulbs don't say dimmable, or your lamps flicker, a few example picks are below. They are examples, not reviews. If your current bulbs already dim smoothly, you don't need any of them.
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A plain dimmable warm-white bulb in the large E27 screw cap, the simplest swap for a lamp whose bulb doesn't dim. Check the lamp's shade opening against its 6 cm diameter, and use it with an LED-suitable dimmer.
Dimmable · Warm white · E27 cap · 8.8 W
A well-known brand's dimmable bulb with a brighter output for reading lamps. Same rule as any dimmable LED: pair it with a dimmer made for LEDs.
Dimmable · Warm white · E27 cap · 10.5 W
Dims in its own electronics, so it works on a plain wall switch that stays on and needs no dimmer. A good route if your old wall dimmer flickers with LEDs.
Dimmable in app · Warm to cool · E27 cap · Filament look
