About this calculator
Watt (W) is the unit of power, and lumen (lm) is the unit of brightness. Different types of light bulbs with the same wattage have very different brightness. LED lights are the brightest and incandescent lights are the dimmest. A watts to lumens converter can help you understand how bright your light bulbs actually are and compare the energy efficiency of different light bulbs. Our free online watts to lumens converter provides a simple, fast, and accurate solution.
Light efficiency of different types of bulbs: LED lamp 9W ≈ 800 lumens, energy-saving lamp 13W ≈ 800 lumens, halogen lamp 40W ≈ 800 lumens, incandescent lamp 60W ≈ 800 lumens. As can be seen, LED lights are 6-7 times more energy efficient than incandescent lights.
Using the watts to lumens converter is easy and intuitive. Just enter the wattage, select the lamp type, hit the conversion button and get instant brightness (lumens) and equivalent power comparisons. This tool is especially useful for shopping for light bulbs, comparing energy efficiency, and making energy-saving retrofits.
What it calculates
The watt to lumen calculator estimates light output from power and luminous efficacy to compare brightness across lamps.
Formula
Luminous flux in lm = power in W * efficacy in lm/W.
Inputs
- Lamp power in W.
- Efficacy in lm/W.
- Lamp type or custom efficiency.
Example
| Power | Efficacy | Estimated lumens |
|---|---|---|
| 10 W | 80 lm/W | 800 lm |
| 15 W | 100 lm/W | 1500 lm |
| 60 W | 15 lm/W | 900 lm |
How to interpret the result
The result is estimated total light output. At the same wattage, LEDs usually produce more lumens than incandescent bulbs.
Common mistakes
- Do not judge brightness by watts alone.
- Use efficacy in lm/W.
- Package-rated lumens are more accurate than estimates.
How to use
Using the watts to lumens converter is easy. First, enter the power (watts) in the input box. Wattage information can be found on the bulb package or on the bulb. For example, 9W, 13W, 60W.
Then, select the bulb type: LED (most energy efficient), energy-saving lamp (CFL), halogen, or incandescent (traditional bulb). Click the "Convert" button.
The converter displays brightness (lumens), efficacy (lm/W) and equivalent power comparison. For example, 9W LED lamp = 810 lumens = 13.5W CFL = 40.5W halogen lamp = 67.5W incandescent lamp. This means that the brightness of a 9W LED lamp is equivalent to that of a 60W incandescent lamp. Click the "Reset" button to clear all inputs and start a new conversion.
Main features
This watt to lumens converter has the following features: supports four types of LED, energy-saving lamps, halogen lamps, and incandescent lamps; uses actual light efficiency data; displays brightness, light efficiency, and equivalent power comparison; helps compare the energy efficiency of different light bulbs; automatically detects invalid input; the interface is simple and intuitive, easy to use; fast response speed, conversion results are displayed instantly; completely free, no registration or download required; supports desktop and mobile device access.
Use cases
Watts to lumens converter is very useful in several scenarios. When purchasing a light bulb, it can be used to understand the actual brightness of the light bulb. For example, how bright is a 9W LED light? Conversion gives about 810 lumens, which is equivalent to a 60W incandescent lamp.
Can be used to evaluate energy efficiency when comparing light bulbs. For example, with the same brightness of 800 lumens, the LED lamp is 9W, the energy-saving lamp is 13W, and the incandescent lamp is 60W. LED lights are the most energy efficient. Can be used to find equivalent bulbs when replacing them. For example, a 40W halogen lamp can be replaced with a 9W LED lamp (same brightness).
In lighting design, it can be used to calculate the total brightness. For example, 5 9W LED lights = 4050 lumens. In cost analysis, it can be used to calculate electricity bills. For example, if a 9W LED lamp is used for 5 hours a day, it consumes 1.35 kilowatt-hours of electricity per month, and the electricity bill is about 0.81 yuan. Whether shopping, comparing or designing, the watts to lumens converter is a useful tool.