Lumens to Watts Calculator — Bulb Power Comparison
Enter the lumen output you need and pick a bulb technology to find out how many watts it takes — then compare all four bulb types side by side to see how much energy and money a more efficient bulb saves.
lm
Bulb technology
Watts required for LED to produce the specified lumens
- 1
Efficacy (LED)
95 lm/WTypical mid-range luminous efficacy for this bulb technology - 2
Power required
800 ÷ 95 = 8.4Watts = Lumens ÷ Efficacy (lm/W)
How does this calculator work?
Watts = Lumens ÷ efficacy. Typical efficacies: LED 95 lm/W, CFL 65 lm/W, halogen 18 lm/W, incandescent 12 lm/W. An 800 lm LED needs roughly 8 W vs 67 W for an equivalent incandescent — saving about 85% of the energy and roughly €12 per year per bulb at 8 h/day use.
Formula
How this is calculated
Lumens measure the brightness of a light source; watts measure how much electrical energy it consumes. The link between them is luminous efficacy (lm/W): how many lumens a bulb produces per watt of input power. Rearranged: W = lm ÷ (lm/W). A 800 lm LED (typical 60 W equivalent) needs only 800 ÷ 95 ≈ 8.4 W; the same brightness from an incandescent needs 800 ÷ 12 ≈ 67 W.
The efficacy values used (LED 95, CFL 65, halogen 18, incandescent 12 lm/W) are representative mid-range figures for consumer products as of 2024. Actual values vary by brand and model: premium LEDs can reach 100–130 lm/W, while cheap LEDs may be as low as 60 lm/W. The comparison is still accurate in direction — LEDs consistently use 5–8× less energy than incandescents for the same light output.
The annual cost saving assumes the bulb runs 8 hours per day at an electricity tariff of €0.20/kWh. Update the lumen input to any target brightness, and the numbers scale proportionally.
Frequently asked questions
A 60 W incandescent produces roughly 800 lumens at about 12 lm/W. An LED rated at 95 lm/W needs only 800 ÷ 95 ≈ 8–9 W to match that brightness. Most LED packaging will say "60 W equivalent" to make this comparison easy.
The efficacy figures are typical mid-range values, not the specification of any specific bulb. Actual wattage can vary ±15–20% depending on the manufacturer and quality. Always check the lumen and watt figures printed on the bulb itself for an exact comparison.
LEDs are better in almost every way: they start instantly at full brightness, last 15 000–50 000 hours (versus 6 000–15 000 for CFL), contain no mercury, and are now similarly priced. CFL bulbs can still make sense if you already have them and they are working, but switching to LED at replacement time is the better long-term choice.
Also known as
TG we-Calculate Editorial Team. (2026). Lumens to Watts Calculator — Bulb Power Comparison [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/lumens-to-watts-calculator
TG we-Calculate Editorial Team. "Lumens to Watts Calculator — Bulb Power Comparison." TG we-Calculate. 2026. https://we-calculate.com/calculator/lumens-to-watts-calculator.
TG we-Calculate Editorial Team, "Lumens to Watts Calculator — Bulb Power Comparison," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/lumens-to-watts-calculator
@misc{wecalculate_lumens_to_watts_calculator, title = {Lumens to Watts Calculator — Bulb Power Comparison}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/lumens-to-watts-calculator}}, year = {2026}, note = {TG we-Calculate} }
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