Lumens to Watts Converter
Know how bright you want a light to be but not which bulb to buy? Enter the lumens and pick a bulb type to see the watts it needs, what the same brightness costs with every other technology, and how much it will cost to run.
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Total brightness: per bulb, or for the whole fixture
Lumens on the box ÷ watts
1 = a single bulb
Typical household LEDs: 80–120
Typical CFLs: 55–70
Leave empty to skip energy and cost
Check your bill for the rate
How to use the Lumens to Watts Converter
- Enter the lumens you want, or tap a preset such as 800 lm (60 W equivalent).
- Choose the bulb type. Pick Custom to type the exact lumens per watt from a bulb's box.
- Split across bulbs if the light comes from several lamps, such as a 4-bulb fixture.
- Adjust the efficacy presets if you know your LEDs or CFLs are more or less efficient than typical.
- Add hours and your electricity price to see the yearly energy use and cost, then copy or download the results.
The lumens to watts formula
watts = lumens ÷ luminous efficacy (lm/W)
Lumens describe light; watts describe the electricity a bulb uses to make it. The bridge between them is luminous efficacy, the number of lumens a technology delivers per watt. That is why the same 800 lumens can cost 9 W or 60 W depending on what is inside the glass.
- LED at 90 lm/W: 800 lm ÷ 90 = 8.9 W.
- CFL at 60 lm/W: 800 lm ÷ 60 = 13.3 W.
- Incandescent: efficacy rises with wattage (about 11 lm/W at 40 W, 16 lm/W at 100 W), so the tool reads the answer off the standard label points: 800 lm ≈ 60 W.
Bulb equivalence table
Typical wattages for the brightness levels printed on US bulb packaging. Use it to replace an old bulb with a newer one of the same brightness.
| Brightness | Incandescent | Halogen | CFL | LED |
|---|---|---|---|---|
| 450 lm | 40 W | 29 W | 8–11 W | 4–6 W |
| 800 lm | 60 W | 43 W | 13–15 W | 7–10 W |
| 1,100 lm | 75 W | 53 W | 18–20 W | 10–13 W |
| 1,600 lm | 100 W | 72 W | 23–27 W | 14–18 W |
| 2,600 lm | 150 W | — | 38–45 W | 23–30 W |
LED and CFL ranges vary by brand and model year. The most efficient LEDs sit at or below the low end of each range.
Tips for choosing bulbs by lumens
- Read the lumens, not the "W equivalent". An "LED 60 W equivalent" only promises about 800 lm; two bulbs with the same equivalent rating can differ by 10–20%.
- Divide lumens by watts on the box to compare efficiency. 1,100 lm from 10 W (110 lm/W) beats 1,100 lm from 13 W (85 lm/W), and you can enter the figure as a custom efficacy above.
- Dimmers and enclosed fixtures may need bulbs rated for them; heat inside a closed globe can shorten LED life.
- Color temperature (2700 K warm white to 5000 K daylight) changes how bright a room feels without changing the lumens.
- Several smaller bulbs spread light more evenly than one bright one. Use "Split across bulbs" to see the watts each lamp needs.
Frequently asked questions
How many watts is 800 lumens?
About 9 W for a typical LED (at 90 lm/W), 13 W for a CFL, 43 W for a halogen and 60 W for an incandescent bulb. That is why 800-lumen LEDs are sold as 60 W equivalents.
What is the formula for lumens to watts?
Watts = lumens ÷ luminous efficacy (lumens per watt). For example, 1,600 lm ÷ 90 lm/W = 17.8 W for an LED. Efficacy depends on the bulb technology, so you need to know the type.
How many watts is 1,600 lumens?
Roughly 18 W of LED, 27 W of CFL, 72 W of halogen or 100 W of incandescent light.
How many lumens per watt does an LED give?
Most household LED bulbs give 80 to 120 lumens per watt, and efficient models go higher. Divide the lumens on the box by the watts to get your bulb's exact figure, then enter it as a custom efficacy.
Why are incandescent bulbs handled differently?
Their efficacy rises with wattage: a 40 W bulb gives about 11 lm/W while a 100 W bulb gives about 16 lm/W. The converter interpolates the standard 450, 800, 1,100, 1,600 and 2,600 lumen label points rather than using one fixed ratio.
Should I buy bulbs by watts or lumens?
By lumens. Watts measure energy use, lumens measure light. Pick the lumens you need, then choose the bulb that delivers them with the fewest watts.
How many lumens do I need for a room?
It depends on the room size and use. As a rough guide a living room needs about 10 to 20 lumens per square foot and a kitchen or workspace 30 to 50. Use the lux to lumens converter for a precise figure.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.