# How to convert lumen to W?

### 2012-07-05 11:27:16

How to convert lumen to W?

Strictly Lumen and Watt are two different unit.

What is Lumen?
A: Lumen is amount of light emitted from light source.
According to Wikipedia, "If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted into that solid angle is one lumen. Alternatively, an isotropic one-candela light source emits a total luminous flux of exactly 4π lumens. The lumen can be thought of casually as a measure of the total amount of visible light emitted." For example, a standard 100 Watt incandescent bulb emits about 1500 lumen.

What is Watt?

The watt is a unit of power. It is a Newton meter per second, or can be given as a joule per second. We often encounter it in electrical calculations, and it is the unit of power for applications there. The formula for power is given here:

P = I x E

In this expression, the power (P) in watts is equal to the current (I) in amps (or amperes, if you prefer) times the voltage (E) in volts.

I think you're asking what is a watt. A watt is a measurement of power, and the simplest example of a watt would be the amount of power that you would have if you had one volt at one amp of current. Or, to put it another way, 1 volt X 1 Amp=1 Watt. To go further, 12 volts at 1 amp equals 12 watts. This is for direct current measurement.

For AC voltage, it varies in that you would multiply the volts by .707 (AC RMS voltage), then multiply by the amps to get your watts total.

But in order to make customers convert them more easily, we can say1watt is about 50~65lumens.

So when you find following description ,you can have a main idea in your mind:
1. one watt flashlight: is about 60lumens
2. three watt flashlight: is about 150lumens
3. five watt falshlight: is about 250lumens

Have you made it clearly now?

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