Lumens to watts calculator
Enter watts or lumens, get the bulb equivalent.
How many lumens replace a 60-watt bulb?
At least 800 lumens, according to ENERGY STAR. The FTC also says a traditional 60-watt incandescent bulb produces about 800 lumens.
What are the other equivalents?
ENERGY STAR lists 450 lumens for a 40-watt bulb, 1,100 for 75 watts, 1,600 for 100 watts and 2,600 for 150 watts.
Why shop by lumens, not watts?
Lumens measure how much light a bulb gives; watts measure the power it uses. An LED makes the same light as an incandescent bulb with far fewer watts, so watts no longer tell you how bright it is.
How much power will my LED use?
Look at the watts on its Lighting Facts label. Divide lumens by watts to compare efficiency: a higher lumens-per-watt number means more light for the same electricity.
What if my bulb is between the listed sizes?
The calculator names the largest incandescent size the bulb meets or exceeds — a 1,000-lumen bulb is at least as bright as a 60-watt one, not yet a 75-watt one.
Is there a formula to convert lumens to watts?
Not one fixed formula. Lumens measure light and watts measure power, and the ratio between them (lumens per watt) depends on the technology. That is why the conversion here uses the incandescent brightness table, not a constant.
Do I need more lumens for a bigger room?
More light is needed to cover a larger area, but how much depends on the room's use and finishes. This calculator only matches the brightness of a bulb you already know.
How the equivalents are built
The brightness values come from the ENERGY STAR table of traditional bulbs: 40 W gives 450 lm, 60 W 800 lm, 75 W 1,100 lm, 100 W 1,600 lm and 150 W 2,600 lm. A bulb counts as equal to an old wattage when its lumens reach that value. Between rows the tool picks the largest wattage that is met: 1,000 lumens is at least a 60-watt bulb and below a 75-watt one. Below 450 lumens there is no listed incandescent equivalent.
Worked example: why watts mislead
Dividing the table's lumens by watts gives the efficiency of the old bulbs: 40 W = 11.3 lm/W, 60 W = 13.3 lm/W, 75 W = 14.7 lm/W, 100 W = 16.0 lm/W, 150 W = 17.3 lm/W. Take a hypothetical LED that gives 800 lumens on 10 watts: that is 80 lm/W, about six times better than the 60-watt bulb. Used 3 hours a day, the 60-watt bulb takes 65.7 kWh a year, and the 10-watt LED 10.95 kWh. Energy is watts × hours ÷ 1,000.
Mistakes to avoid
Do not read the watts printed on an LED package as brightness; they say only how much power it draws. Check the lumens on the label instead. Another slip is to treat the equivalent as exact: bulbs also differ in color temperature and in how the light spreads, so two bulbs with the same lumens can look different once installed. And a number of lumens cannot be turned into watts for an LED without knowing that bulb's own lumens per watt.
Sources: ENERGY STAR, brightness table for replacing traditional bulbs; FTC (lumens, not watts, show brightness). Related tools: electricity cost calculator, watts to amps calculator, LED resistor calculator.