Enter the electrical power (watts) and luminous efficacy (lumens per watt) into the calculator to estimate light output. If you only know voltage, you must also know the operating current (or device power) to estimate lumens—voltage alone is not enough. This calculator can also solve for any variable when the others are known.
Volts To Lumens Formula
The following formula can be used to estimate lumens from voltage when the electrical current and the light source’s luminous efficacy are known.
L = V \times I \times \eta
Variables:
- L is the light output (lumens)
- V is the voltage (volts)
- I is the electrical current (amps)
- η is the luminous efficacy (lumens per watt, lm/W)
This relationship comes from two standard definitions: electrical power is P = V × I (watts), and light output can be estimated as L = P × η (lumens), where η is luminous efficacy in lm/W. In real lighting systems, current and efficacy depend on the driver, LED/lamp type, temperature, optics, and operating point—so voltage alone cannot be converted to lumens without additional information.
| Volts (V) | Lumens (lm) |
|---|---|
| 0.5 | 50 |
| 1 | 100 |
| 1.5 | 150 |
| 3 | 300 |
| 3.3 | 330 |
| 5 | 500 |
| 6 | 600 |
| 9 | 900 |
| 12 | 1200 |
| 18 | 1800 |
| 24 | 2400 |
| 36 | 3600 |
| 48 | 4800 |
| 60 | 6000 |
| 72 | 7200 |
| 96 | 9600 |
| 110 | 11000 |
| 120 | 12000 |
| 220 | 22000 |
| 240 | 24000 |
| Example only. Uses L = V × I × η with I = 1 A and η = 100 lm/W. Do not assume a fixed current from supply voltage; actual current and lumen output depend on the lamp/driver and operating conditions. | |
What is Volts To Lumens?
“Volts to lumens” usually refers to estimating a light’s output (lumens) from electrical information. There is no universal direct conversion from volts to lumens because volts measure electrical potential (voltage), not power. To estimate lumens you generally need power (watts) and luminous efficacy (lm/W), or you need voltage plus current (since power is P = V × I).
How to Calculate Volts To Lumens?
The following steps outline how to estimate light output using L = V × I × η.
- Determine the voltage (V) across the light/load in volts.
- Determine the electrical current (I) through the light/load in amps.
- Determine the luminous efficacy (η) in lumens per watt (lm/W) for the light source at its operating conditions.
- Calculate light output: L = V × I × η (lumens).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
voltage (V) = 12 volts
current (I) = 0.50 amps
luminous efficacy (η) = 100 lumens per watt
