What is the difference between lumens and watts?

Lumens and watts are both terms that are used in lighting but they measure two different aspects.  Previously with incandescent and halogen lighting you would understandably be correct in believing that the higher the wattage of a bulb the brighter it would be.  However, this is no longer the case as LED lighting can produce the same amount of brightness for a much lower wattage.  This is when lumens become relevant as this refers to the measurement of the level of brightness rather than the amount of wattage used.

Lumens are a measure of light output which tells us how bright a bulb actually appears.  The higher the amount of lumens, the brighter the light.  A LED bulb using only 8W to 10W for example may produce around 800 lumens.  This is the same amount of brightness emitted by an older 60W incandescent bulb.

When you are purchasing LED lighting lumens are far more important than watts for determining brightness.  Many LED packaging labels and websites now include wattage equivalence guides on their products to help consumers compare older and newer technologies.

Below are some comparison examples comparing the wattage of LED and incandescent lights and their lumen outputs:

Understanding what lumens are will help you to choose suitable brightness levels for different rooms and applications.  You may want a lower amount of lumens for a bedroom and a higher amount of lumens for a kitchen or office as these areas often require brighter lighting. 

To summarise - watts will tell you how much electricity a bulb consumes and lumens will tell you how much light it produces.  For brightness you should always go by lumens as this measurement will be the same for all types of lighting technology.