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Watts tell you how much power a lamp uses. Lumens tell you how much light it actually produces. For picking a desk lamp, lumens is the number that matters.
What is a lumen?
A lumen (lm) is a unit measuring the total amount of visible light emitted by a source. More lumens = more light. A candle produces about 12 lumens. A standard 60W incandescent: around 800 lumens. A desk lamp with 400 lumens gives you enough to light your immediate work surface without blinding you.
Lumen requirements by task
| Use case | Recommended lumens |
|---|---|
| Desk lamp alongside a monitor | 200–400 lm |
| Reading or writing (no monitor) | 400–700 lm |
| Art, drafting, fine detail work | 700–1000 lm |
| General room ambient | 800–1600 lm |
The monitor factor
If you’re using a monitor, your screen is already producing significant light. A desk lamp at 400+ lumens will compete with the screen and create glare. Keep your desk lamp in the 200–350 lumen range and let the monitor handle display brightness separately.
Lumens vs. watts — the conversion
For LED desk lamps: roughly 100 lumens per watt is the efficiency target. So a 4W LED should produce around 400 lumens. If a lamp says “5W” but doesn’t list lumens, assume 350–450 lm. Always look for the lumen spec directly — wattage alone doesn’t tell you brightness.
Dimmability changes everything
A dimmable 500 lm lamp is more flexible than a fixed 300 lm lamp. You can dial it down to 200 lm for evening use and push it to 400 lm during daytime focus work. Buy the dimmer option, then adjust down. Don’t buy the fixed lamp and wish you had more range.
