About this calculator
Lumens (lm) are a unit for measuring the brightness of a light bulb, and watts (W) are a unit for measuring power. Different types of light bulbs require different power for the same brightness. LED lights are the most energy efficient, while incandescent lights consume the most power. A lumen to watt converter can help you choose the right wattage bulb for your brightness needs. Our free online lumens to watts converter provides a simple, fast, and accurate solution.
Light efficacy (lumens/watt) of different types of bulbs: LED lamps about 80-100 lm/W, energy-saving lamps about 50-70 lm/W, halogen lamps about 15-25 lm/W, incandescent lamps about 10-15 lm/W. For example, for 800 lumens of brightness, an LED light requires only 9W, while an incandescent light requires 60W.
Using the lumens to watts converter is easy and intuitive. Just enter the lumens value, select the bulb type, hit the conversion button and you'll instantly get the power you need. This tool is especially useful for purchasing light bulbs, replacing light bulbs, and making energy-saving retrofits.
What it calculates
The lumen to watt calculator estimates power needed to produce a given light output from luminous efficacy, useful for LEDs, incandescent bulbs, and CFLs.
Formula
Power in W = luminous flux in lm / efficacy in lm/W. Higher efficacy needs fewer watts for the same brightness.
Inputs
- Light output in lumens.
- Luminous efficacy in lm/W.
- Lamp type or custom efficiency.
Example
| Input | Efficacy | Result |
|---|---|---|
| 800 lm | 80 lm/W | 10 W |
| 1600 lm | 100 lm/W | 16 W |
| 450 lm | 15 lm/W | 30 W |
How to interpret the result
The result is estimated power. Bulbs with the same lumens can use very different wattage because their efficacy differs.
Common mistakes
- Watts are not brightness; lumens better describe light output.
- Different lamp types have different efficacy.
- Actual power can vary by driver and product design.
How to use
Using the Lumens to Watts converter is easy. First, enter the lumen value in the input box. Lumen information can be found on the bulb packaging. For example, 800 lumens, 1200 lumens, 1600 lumens.
Then, select the bulb type: LED (most energy efficient), energy-saving lamp (CFL), halogen, or incandescent (traditional bulb). Click the "Convert" button.
The converter will display the required power (watts) and light efficacy (lm/W). For example, an 800-lumen LED light requires about 9W, while an incandescent light requires about 67W. This means that LED lights are more than 7 times more energy efficient than incandescent lights. Click the "Reset" button to clear all inputs and start a new conversion.
Main features
This lumen to watt converter has the following features: supports four types of LED, energy-saving lamps, halogen lamps, and incandescent lamps; uses actual light efficiency data; displays power and light efficiency; helps choose energy-saving light bulbs; automatically detects invalid inputs; 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
Lumens to Watts converter is very useful in several scenarios. When shopping for light bulbs, this can be used to determine how many watts of light bulbs you need. For example, if you need 800 lumens of brightness, choose 9W for LED lights and 60W for incandescent lights.
Can be used to find equivalent LED bulbs when replacing bulbs. For example, a 60W incandescent lamp (approximately 800 lumens) can be replaced with a 9W LED lamp. During energy-saving renovation, it can be used to calculate the energy-saving effect. For example, replacing 10 60W incandescent lamps with 9W LED lamps will save 510W per hour, use 5 hours per day, and save 76.5 kWh per month.
In lighting design, it can be used to select bulbs with appropriate power. In cost analysis, it can be used to compare the energy consumption and electricity bills of different light bulbs. Whether it's home, office or business, a lumens to watts converter is a useful tool.