While it is true that LEDs are the most efficient sources of light that we have, they are still very inefficient when you look at the numbers. The efficiency of an average LED bulb is around forty per cent. That means the remaining 60 per cent of the power turns into heat. But this is a huge improvement over the traditional incandescent bulbs that only had an efficiency of 5%. Therefore, LED strips might not get as hot as an incandescent bulb, but it is quite normal for them to get warm. LED strips with higher power output usually have heat sinks in them to dissipate this heat.