About the Lumens to Watts Converter
This lumens to watts converter tells you how many watts a bulb needs to produce a given brightness. Lumens measure light output and watts measure power use, so the answer depends on the bulb technology: an LED makes roughly six times more light per watt than an old incandescent bulb. Pick the bulb type (or enter your own lumens-per-watt figure from the box) and you get the wattage, the incandescent-equivalent rating, and yearly energy use and cost.
Use it when replacing bulbs — packaging lists lumens, but most people remember "a 60 W bulb" — when planning lighting for a room, or when estimating how much switching to LED will save. For example, a standard 60 W incandescent gives about 800 lumens, which an LED delivers with 8–10 W.
The efficacy values are typical figures for household bulbs (incandescent ≈ 13–16 lm/W, halogen ≈ 18, CFL ≈ 60, LED ≈ 90). Real bulbs vary, so for an exact figure divide the lumens by the watts printed on your bulb and use the custom option.
With the default inputs, the power needed is 8.89 W. Change any value above to recalculate instantly.
How to use the lumens to watts converter
- 1Enter the brightness you want in lumens (800 lm ≈ an old 60 W bulb).
- 2Choose the bulb type, or pick Custom and enter lumens per watt from the box.
- 3Set how many hours a day the light is on and your electricity price.
- 4Read the wattage needed, the incandescent equivalent and the yearly cost.
- 5Compare bulb types in the chart to see how much power each needs.
Formula and method
Luminous efficacy is how many lumens a bulb produces per watt of electricity. Dividing the brightness you want (in lumens) by the efficacy gives the power the bulb needs. Typical efficacies are about 18 lm/W for halogen, 60 lm/W for CFL and 90 lm/W for a household LED (good LEDs exceed 100 lm/W); incandescent bulbs manage roughly 11–16 lm/W.
Yearly energy is the wattage times hours per day times 365, divided by 1,000 to get kilowatt-hours; multiply by your electricity price for the running cost. The incandescent equivalent is interpolated from the standard packaging equivalences (450 lm ≈ 40 W, 800 lm ≈ 60 W, 1,100 lm ≈ 75 W, 1,600 lm ≈ 100 W, 2,600 lm ≈ 150 W), and the saving compares your bulb with that wattage.
- lm
- Lumens — total visible light output
- lm/W
- Luminous efficacy of the bulb
- W
- Electrical power the bulb draws
Worked examples
800 lumen LED (60 W replacement)
800 ÷ 90 = 8.9 W. At 3 hours a day that is 8.89 × 3 × 365 ÷ 1000 = 9.73 kWh, or $1.56 a year at $0.16/kWh. A 60 W incandescent would use 65.7 kWh ($10.51), so the LED saves about $8.95 a year (85% less energy).
1,600 lumen CFL
1,600 ÷ 60 = 26.7 W, replacing a 100 W incandescent (1,600 lm is the standard 100 W equivalent). Running 3 hours a day uses 29.2 kWh a year.
High-efficiency 450 lm LED, custom 110 lm/W
450 ÷ 110 = 4.09 W. On for 5 hours a day it uses 7.47 kWh a year, costing $2.24 at $0.30/kWh.
Frequently asked questions
How many lumens is a 60 watt bulb?+
A standard 60 W incandescent bulb gives about 800 lumens. An LED of 8–10 W produces the same light, which is why LED boxes say "60 W equivalent".
How do I convert lumens to watts?+
Divide lumens by the bulb’s efficacy in lumens per watt. For an LED at 90 lm/W, 1,100 lumens ÷ 90 = 12.2 W.
How many lumens per watt does an LED give?+
Most household LED bulbs give 80–110 lumens per watt, and the best exceed 150 lm/W. Incandescent bulbs manage only about 12–15 lm/W.
How many lumens do I need for a room?+
A common rule of thumb is 10–20 lumens per square foot for living rooms and bedrooms, 30–40 for kitchens and bathrooms, and 70–80 for task areas such as desks and workbenches. A 150 sq ft living room would need roughly 1,500–3,000 lumens in total.
Are watts a measure of brightness?+
No. Watts measure how much electricity a bulb uses; lumens measure how much light it gives. Compare bulbs by lumens and use watts to estimate running cost.