Why dimmable LED bulbs flicker

This page does not recommend a product, because in most cases a product is not the fix. Work through these in order - it takes about five minutes and costs nothing.

1. Does it flicker only when dimmed? If it is steady at full and flickers as you dim, the dimmer is almost certainly the cause. If it flickers at full brightness too, go to step 4.
2. How many bulbs are on the circuit? Take one out. If the flicker gets worse, you are below the dimmer's minimum load. If it gets better, the dimmer is struggling with the total.
3. What does the dimmer say? Look at the faceplate or take the plate off and read the back. Anything that does not say "LED" or "trailing edge" and predates about 2010 was designed for incandescent filaments.
4. Is the bulb marked dimmable? A non-dimmable LED on a dimmer will flicker, buzz, or refuse to dim. This is the one case where the bulb is straightforwardly at fault.
5. Does it flicker in a different fixture? Move the bulb to a lamp with no dimmer. Steady there, flickering on the dimmer, confirms it.

An incandescent bulb is a resistor. It draws a lot of current, and its filament has thermal inertia, so it smooths over the chopped waveform a dimmer produces - you get a continuous glow.

An LED bulb is an electronic driver feeding semiconductors. It draws a fraction of the current, has no thermal inertia at all, and responds to the supply almost instantly. Chop the waveform the way a leading-edge dimmer does and the LED follows it faithfully, which you see as flicker.

The minimum-load problem is the same story from the other end. Many older dimmers need a certain wattage present to regulate at all - commonly around 40W. Three modern LEDs might total 24W, which is below the threshold, and the dimmer behaves erratically at the bottom of its range.

The renter column is the useful one, because replacing a dimmer is an electrical alteration and generally needs permission - see the lease rules page. Leaving the wall dimmer at 100% and using a smart bulb for brightness sidesteps the whole problem: the bulb dims electronically, the dimmer never leaves full, and nothing in the wall is touched.