900 lumens is approximately 7.5 watts when converted assuming an average luminous efficacy of 120 lumens per watt.
This conversion uses an estimated efficiency for LED or similar light sources where the brightness in lumens divided by the efficacy gives the power consumption in watts. Since lumens measures brightness and watts measures power, the conversion depends on the light source type.
Conversion Tool
Result in watts:
Conversion Formula
The formula to convert lumens to watts depends on the luminous efficacy of the light source, measured in lumens per watt (lm/W). Watts indicate energy usage; lumens indicate brightness. To find watts, you divide the lumens by the luminous efficacy.
Mathematically:
Watts = Lumens ÷ Luminous Efficacy (lm/W)
The luminous efficacy varies based on bulb type, for example, LEDs have about 120 lm/W, incandescent bulbs around 15 lm/W.
Example: For 900 lumens, assuming 120 lm/W, Watts = 900 ÷ 120 = 7.5 watts. This means a bulb producing 900 lumens would consume roughly 7.5 watts.
Conversion Example
- Example 1: Convert 600 lumens to watts
- Assuming luminous efficacy = 120 lm/W
- Calculate: Watts = 600 ÷ 120 = 5 watts
- A bulb emitting 600 lumens consumes about 5 watts
- Example 2: Convert 1500 lumens to watts
- Using 120 lm/W as efficacy
- Watts = 1500 ÷ 120 = 12.5 watts
- This bulb uses 12.5 watts to emit 1500 lumens
- Example 3: Convert 3000 lumens to watts
- With luminous efficacy of 120 lm/W
- Watts = 3000 ÷ 120 = 25 watts
- Power consumption of 25 watts for 3000 lumens brightness
- Example 4: Convert 450 lumens to watts
- Efficacy taken as 120 lm/W
- Watts = 450 ÷ 120 = 3.75 watts
- Energy usage about 3.75 watts
Conversion Chart
The table below shows how lumens values from 875.0 to 925.0 convert to watts, assuming 120 lm/W luminous efficacy. To use the chart, find the lumen value you need, then read across to find the estimated wattage.
| Lumens | Watts |
|---|---|
| 875.0 | 7.29 |
| 880.0 | 7.33 |
| 885.0 | 7.38 |
| 890.0 | 7.42 |
| 895.0 | 7.46 |
| 900.0 | 7.50 |
| 905.0 | 7.54 |
| 910.0 | 7.58 |
| 915.0 | 7.63 |
| 920.0 | 7.67 |
| 925.0 | 7.71 |
Related Conversion Questions
- How many watts does a 900 lumen LED bulb consume?
- What is the wattage equivalent of 900 lumens for incandescent bulbs?
- How to convert 900 lumens to watts for fluorescent lights?
- Does 900 lumens correspond to 7.5 watts in LED lights?
- What luminous efficacy should I use to convert 900 lumens to watts?
- Can I estimate power consumption from 900 lumens without bulb type?
- What is the difference in watts for 900 lumens between LED and halogen bulbs?
Conversion Definitions
Lumens: Lumens measure the total amount of visible light emitted by a source, representing brightness as perceived by the human eye. It quantifies how much light is produced in all directions, not the energy consumed, and helps compare light sources based on output.
Watts: Watts are a unit of power representing the rate at which energy is used or consumed. For lighting, watts indicate how much electrical power a bulb needs to produce light, regardless of brightness, reflecting energy consumption rather than light output.
Conversion FAQs
Why can’t I convert lumens to watts without knowing the bulb type?
Lumens measure brightness, watts measure power consumption. Different bulbs produce different lumens per watt. Without knowing the bulb’s luminous efficacy, converting lumens to watts is inaccurate because energy efficiency varies widely between LEDs, incandescent, fluorescent, etc.
Does the 120 lumens per watt apply for all bulbs?
No, 120 lumens per watt is an average for LED bulbs. Other types have different efficacies, like incandescent bulbs around 15 lm/W or fluorescents about 60 lm/W. Using the correct efficacy for the bulb type is necessary for precise conversions.
How does luminous efficacy affect lumens to watts conversions?
Luminous efficacy links lumens and watts by showing how efficiently electrical power is converted to visible light. Higher efficacy means fewer watts for the same lumens. Without efficacy, converting lumens to watts would lack context about bulb efficiency.
Can I use this conversion for outdoor lighting?
The formula applies but depends on the type of fixture and bulb used outdoor. Since different outdoor lights have varying efficacies, confirm the specific light source’s lm/W value to get an accurate wattage from lumens.
Is it possible to measure lumens directly from a bulb?
Measuring lumens directly requires specialized instruments like integrating spheres or light meters. Usually, manufacturers provide lumen ratings, so it’s uncommon for consumers to measure lumens themselves.