About the Lumens to Watts Calculator
Lumens measure the amount of light a bulb produces, while watts measure the power it uses. In the days of filament bulbs, watts were a good guide to brightness, but modern lamps give far more light per watt, so the old habit of shopping by watts no longer works. This calculator converts lumens to watts for the main bulb types using typical efficacy figures, and also converts watts to lumens. It shows the old-style incandescent equivalent too, so you can match a new LED to the bulb it replaces. You can enter your own efficacy if the pack gives one.
Updated October 2026
How to use the Lumens to Watts Calculator
- 1Choose whether to find watts or lumens.
- 2Pick the bulb type, or choose your own efficacy.
- 3Enter the brightness in lumens, or the power in watts.
- 4Read the result and the efficacy that was used.
- 5Check the incandescent equivalent when you are comparing bulbs.
Quick equivalents
- 450 lumens: about 40 W incandescent, 5 W LED.
- 800 lumens: about 60 W incandescent, 8 W LED.
- 1,100 lumens: about 75 W incandescent, 11 W LED.
- 1,600 lumens: about 100 W incandescent, 16 W LED.
- 2,600 lumens: about 150 W incandescent, 26 W LED.
Saving energy
Replacing an 800-lumen incandescent bulb with an LED saves about 50 watts. If the light is on for four hours a day, that is 73 kilowatt-hours a year. At 0.20 per kilowatt-hour, the saving is roughly 14.60 a year per bulb, and LEDs also last far longer, so the bulb pays for itself quickly.
When you shop, look for the lumens figure on the box rather than the watts, and compare the colour temperature as well. Around 2,700 kelvin gives a warm, yellowish light like old bulbs, 4,000 kelvin looks neutral and 6,500 kelvin is cool daylight white. Dimmable bulbs say so on the pack, and not every LED works with every dimmer, so check compatibility before replacing a bulb on a dimmer circuit or in an enclosed fitting.
More lighting tools
Use the Lumens and Lux Calculator for illuminance, the Lux to Watts Calculator to plan a room, the Candela to Lumens Calculator for spotlights, the Energy Cost Calculator for running costs and the Unit Converter for lengths and areas.
Features
- Lumens to watts and watts to lumens
- Presets for incandescent, halogen, CFL and LED
- Custom efficacy option
- Incandescent equivalent
- Clear explanation of the figures
- Free and private
Frequently asked questions
How many watts is 800 lumens?
About 8 watts for an LED at 100 lumens per watt. A halogen bulb needs about 44 watts, a CFL about 13 watts and an old incandescent bulb about 57 watts to give the same 800 lumens.
What is luminous efficacy?
It is the number of lumens a lamp produces for each watt it consumes. Incandescent bulbs manage about 14 lumens per watt, CFLs 50 to 70, and LEDs 80 to 150 or more. Higher efficacy means a lower electricity bill for the same light.
Why can't I convert lumens to watts exactly?
Because the link depends on the lamp. Two bulbs with the same lumens can use quite different watts, depending on the technology and design. The calculator uses typical values, and the pack of your bulb is the best source for its real figures.
How many lumens do I need for a room?
A common guide is 300 to 400 lumens per square metre in kitchens and work areas, 150 to 200 in living spaces and about 100 in hallways. The Lux to Watts Calculator on this site works out a total for a room.
What is a 60 watt equivalent LED?
A traditional 60 watt bulb gave around 800 lumens, so a bulb sold as a 60 watt equivalent LED produces about that much light while using roughly 8 watts.
Do colour and beam angle matter?
Lumens count all the light a lamp gives out in every direction. A spotlight with a narrow beam puts more of it on one spot, so for a spotlight, candela and beam angle say more about the effect. The Candela to Lumens Calculator converts between them.