Can LED Lights be Dimmed? All About LED Dimming Problems

Are all LED lights dimmable? Can LED lamps be dimmed at all? Which dimmer is suitable for LED lamps? These and many similar questions often arise when it comes to adjusting the brightness of LED lamps. In this guide you will learn about the obstacles of LED technology and how you can successfully dim LED lights.

The LED dimmer problem

Old incandescent bulbs and halogen bulbs had an advantage in addition to all their disadvantages. These lamps could be easily operated with a dimmer. Adjusting the brightness was no problem. In the meantime, LED lighting technology has established itself and offers many advantages over the old light sources. However, LED technology is much more complex and brings in some challenges.

Dimming of LED lights is one of the most common difficulties when converting to LED lighting. However, this is primarily due to the fact that many people simply assume that LED’s can be dimmed just as easily as the old light sources. If this does not work without problems, sometimes the entire LED technology is demonized as not mature.

The devil is in the details

If you follow the tips below, nothing stands in the way of your dimmable LED lighting.

Dimming LED lamps

LED illuminates and luminaires can also be dimmed so their brightness is adjustable. But in contrast to the conventional light sources, it must be explicitly stated that the LED lamp is dimmable. You will find this information in the product description or on the lamp packaging. If there is no indication for dimming, the lamp cannot be dimmed.

Not all LED lamps are dimmable

When purchasing, make sure that the desired LED lamp is marked as dimmable.

Use appropriate dimmer

Use an appropriate dimmer, which is suitable for your LED lamps.

Technical challenges of dimming

The main difference between conventional light sources and LED lamps lies in the LED driver. The old filament lamps were directly connected to the mains voltage. In simple terms, the forward phase control dimmers used at the time reduced the mean voltage that arrived at the filament. As a result the lamp got darker.

The brightness of light emitting diodes is not regulated by the voltage, but by the current or a so-called pulse width modulation. This regulation as well as the conversion of the mains voltage into the internal low voltage is done by a control electronics integrated in the LED lamp. If the LED lamp should be dimmed, this internal circuit must be designed for this purpose.

Greater complexity of LED technology

The dimming process of an LED lamp is more complex than with old light sources. Fortunately, consumers do not have to concern themselves with the technical details. Just make sure that the lamp is marked as dimmable.

Why aren’t all LED lamps dimmable?

This question arises after finding out that there is a large number of dimmable LED lamps on the market. The dimming of LEDs is therefore technically possible. Why isn’t dimmable technology built into all illuminants and luminaires? The main reason is the higher effort regarding the internal electronics which leads to higher costs. Dimmable LED lamps are usually somewhat more expensive than non-dimmable versions.

If all LED lamps were suitable for connection to a dimmer, LED lighting would be more expensive overall. In most rooms (such as corridors, kitchens, bathrooms, cellars) it is not necessary to adjust the brightness at all. Therefore, it is generally cheaper to pay the surcharge for dimming only for rooms where adjustable brightness matters (such as living rooms).

Price difference between dimmable/not dimmable

Dimmable LED lamps usually cost a little more due to higher switching costs.

Dimming non-dimmable LED lights?

One could be tempted to connect non-dimmable LED lamps to a dimmer anyway. In rare cases this can even work. But in most cases the following effects may occur:

  • Lamp remains dark
  • Brightness can’t be controlled
  • LED flickers
  • LED hums
  • LED breaks down

When operating a non-dimmable LED on a dimmer, many undesirable side effects can occur. Either the lamp does not glow at all or cannot be regulated. In other cases, the lamp flickers or makes unusual noises. All effects can cause the non-dimmable lamp to break sooner or later. Even if the dimmer is always set to 100%, the same effects can occur.

Operate only dimmable LED lamps on the dimmer

Due to the complex internal structure, only LED lamps marked as dimmable should be operated on a dimmer.

Which LED lamps are dimmable?

No general statement can be made here. Whether an LED illuminant or an LED luminaire is suitable for use with a dimmer can be seen from the marking. Especially for LED bulbs there is a huge selection of dimmable models. The proportion of dimmable LED luminaires is slightly smaller. Many online shops offer a sorting function where you can filter by dimmable lamps.

LED transformer dimming

When using low-voltage LED lights, an LED power supply is required. Please note that both the LED lamps and the LED transformer must be dimmable. Dimmable LED transformers also have a corresponding marking. If only one component in the entire chain (dimmer – transformer – illuminant) is not marked as dimmable, difficulties or defects are inevitable.

Which dimmer for LED lamps?

In addition to a dimmable lamp, a dimmer suitable for LED technology must also be used. In addition to various dimmer variants (rotary knob, touch dimmer, with remote control), these work internally with one of the following techniques:

  • Forward phase control
  • Reverse phase control

The dimmers installed for older incandescent light sources work with forward phase control technology. These are primarily suitable for resistive loads. However, LED lamps represent a capacitive load. The old dimmers are therefore mostly unsuitable for the new LED lamps. Most LED lamps require a reverse phase control dimmer.

Dimmer Compatibility list

In the early days of LED technology there were big compatibility issues despite dimmable LED lamps and LED dimmers. A too small dimming range or other side effects were the result. This has improved in the meantime. But even today there is still no hundred percent guarantee that a dimmable LED lamp will function perfectly with any LED dimmer.

For this reason, some lamp manufacturers publish dimmer compatibility lists for their dimmable bulbs and luminaires. The manufacturer is therefore testing the LED lamp with LED dimmers widely available on the market. The results are summarized in the compatibility list. Such lists can be found in a search engine of your choice, for example with the search term dimmer compatibility list manufacturer name.

Such compatibility lists can be found primarily from brand manufacturers. Philips provides this compatibility list for retrofit lamps, among other things.

Safety with tested compatibility

You can find out if your dimmable LED lamp works perfectly with a particular LED dimmer. Use the compatibility lists provided by the manufacturers. Product reviews in online shops can also help with the selection.

Dimmer minimum load and maximum load

LED dimmers only operate within a certain load range. This minimum and maximum load is specified in the product description or in the data sheet. If a load range from 10 to 45 watts is specified, you should only connect LED lamps in this wattage range to the dimmer. If the minimum load is undershot, the LED lamp will probably remain dark, if overloaded, a fuse will probably trip.

Pay attention to minimum and maximum load

Always select the load range of the LED dimmer to match your dimmable LED lamps.


There are both dimmable and non-dimmable LED illuminants and luminaires on the market. When selecting dimmable LED lamps, pay attention to the dimming mark. The dimmer must also be selected to match the LED lamp. You have the best chance of achieving perfectly dimmable lighting if you choose an LED dimmer from the corresponding compatibility list of lamp manufacturers.