Find out the lumens equivalent of watts for your lighting with our calculator. Essential for lighting designers and energy savers.
How It Works
At the core of the Watts to Lumens Calculator is a simple equation:
${\mathit{\Phi}}_{\mathbf{v}}\mathbf{\left(}\mathit{l}\mathit{m}\mathbf{\right)}\mathbf{}\mathbf{=}\mathbf{}\mathit{P}\mathbf{\left(}\mathit{W}\mathbf{\right)}\mathbf{\times}\mathit{\eta}\mathbf{(}\mathit{l}\mathit{m}\mathbf{/}\mathit{W}\mathbf{)}$
Here's a breakdown:
This equation forms the basis for translating electrical power into visible light output, providing insights into the brightness you can expect from a specific amount of power.
Enter Power: Input the power of your light source in watts.
Luminous Efficacy: Specify the luminous efficacy, usually in lumens per watt (lm/W).
Get Luminous Flux: The calculator will display the brightness in lumens based on your inputs.
This process allows you to understand how much light a specific amount of power will produce.
Sometimes, manual calculations are necessary, especially for low-wattage LEDs. The formula is:
$P\left(W\right)=\frac{{\Phi}_{v}\left(lm\right)}{\eta (lm/W)}$
This equation helps you determine the power your light source needs to achieve a specific brightness.
To find the luminous efficacy of a bulb when you know its power and luminous flux, you can rearrange the formula:
$\eta (lm/W)=\frac{{\Phi}_{v}\left(lm\right)}{P\left(W\right)}$
This equation allows you to assess how efficiently a light bulb converts power into visible light.
Multiply the voltage by the amperes (current): Watts = Volts × Amps. Or,
divide lumens by luminous efficacy: Luminous Efficacy = Lumens/Watts
Know the luminous efficacy of the bulb and use the formula:
Luminous Flux (lm) = Power (W) × Luminous Efficacy (lm/W). For example, if a 500-watt bulb has 40 lumens per watt, it gives 20,000 lumens.
LEDs are way more energy-efficient. They use 7 to 10 times less power for the same brightness. Calculate LED wattage with Watts = Lumens / Luminous Efficacy
Bulb light color is measured in Kelvin (K). Lower values are warm and yellowish, higher values are cool and bluish. Normal lighting ranges from 2700 K to 4100 K.