Dimmer switches restrict the amount of power that is circulated though your light bulbs. In order to achieve this, they trim some of the waveform, on the trailing edge or leading edge of the wave.
Today LED bulbs are compliant with most trailing edge dimmers in households. They are more expensive and more complex than leading edge dimmers but they operate noiselessly, have a soft start and offer smooth control, which make them extremely popular, and also increases the life span of LEDs.
Trailing edge dimmers
Instead of switching voltage off completely, trailing edge dimmers fade voltage by applying resistance. This means more heat is dissipated with the resistance.
Leading edge dimmers
Leading edge dimmers are used most often with mains halogen light bulbs and incandescent bulbs. they shorten the cycle at the input waveform’s leading edge.
Dimmer switches are manufactured with maximum and minimum ratings in watts but it is not possible to calculate LED loading in the same way you would an incandescent or halogen bulb. Rather, take the dimmer switch’s maximum rating and divide it by 10. See example below:
It is important to note that many manufacturers claim their LED lights are compatible with household dimmer switches but this is highly unlikely because there are just too many of them. Rather check this before you buy.