Lumens and watts are often confused: wattage is how much electricity the light uses, not the light emitted from the bulb. Make sure that the measurement you are looking for is lumen and not wattage.
A lumen quantifies how much light is emitted by a source (for example, a light bulb) and is an SI (metric) unit of light power. Candle power (commonly called candela) measures the brightness of the light at the source and is an SI measurement of how much light falls a certain distance from the source. Candle power and lumens measure two different things, therefore it's impossible to accurately convert between the two. However, you can get a good approximation with the following candle power to lumens formula: L=C/0.07958, where L is lumens and C is candle power.
Determine the candlepower of your light source. A light meter can be used to measure candlepower.
Insert the candlepower measurement into the following formula: L=C/0.07958, For example, 200 candlepower would equal: L = 200 candlepower / 0.07958.
Do the division using a calculator: 200 candlepower / 0.07958 = 2 513 lumens.
- light on image by timur1970 from Fotolia.com