What Are Lumens?
Lumens measure how much visible light a bulb produces — the higher the lumen count, the brighter the light. Lumens have replaced watts as the standard way to compare bulb brightness, since watts only measure energy consumption, not actual light output.
Why lumens matter more than watts
With traditional incandescent bulbs, watts were a reasonable proxy for brightness, since all incandescent bulbs produced light in a similar, fairly inefficient way. LED bulbs use far less energy to produce the same amount of light, so comparing wattage between an old incandescent bulb and a new LED tells you very little. Lumens give a direct, consistent measure of brightness regardless of the bulb technology.
How many lumens do I need?
This depends on the room and the purpose of the light. As a general guide, task lighting — for reading, cooking, or close work — benefits from a higher lumen output, while ambient or mood lighting can work well with fewer lumens. See our mood lighting guide and task lighting guide for more detail on how much light different purposes need.
Lumens vs colour temperature
It's worth not confusing lumens with colour temperature. Lumens measure brightness. Colour temperature, measured in Kelvin, measures the tone of the light — whether it appears warm and yellow, or cool and blue-white. See our warm white vs cool white guide for more on colour temperature.
Frequently Asked Questions
What are lumens?
Lumens measure the total amount of visible light a bulb produces. The higher the lumen figure, the brighter the bulb.
Why don't we compare bulbs by watts anymore?
Watts measure energy consumption, not brightness. Since LED bulbs use far less energy than incandescent bulbs to produce the same amount of light, watts are no longer a reliable way to compare brightness between different bulb types.
Is a higher lumen count always better?
Not necessarily — it depends on the purpose of the light. Task lighting benefits from higher lumens, while mood or ambient lighting often works better with a lower lumen output.
Related guide: compare lumens vs watts.