Enter the luminosity (watts) and the distance (m) into the Brightness Ratio Calculator. The calculator will evaluate and display the Brightness Ratio.

## Brightness Ratio Formula

The following formula is used to calculate the Brightness Ratio.

BRR = L / (4*pi*d^2)
• Where BRR is the Brightness Ratio (watts/m^2)
• L is the luminosity (watts)
• d is the distance (m)

To calculate the brightness ratio, divide the luminosity by the 4 times pi times the distance squared.

## How to Calculate Brightness Ratio?

The following example problems outline how to calculate Brightness Ratio.

Example Problem #1:

1. First, determine the luminosity (watts).
• The luminosity (watts) is given as: 500.
2. Next, determine the distance (m).
• The distance (m) is provided as: 5.
3. Finally, calculate the Brightness Ratio using the equation above:

BRR = L / (4*pi*d^2)

The values given above are inserted into the equation below and the solution is calculated:

BRR = 500 / (4*3.14159*5^2) = 1.591 (watts/m^2)

Example Problem #2:

For this problem, the variables required are provided below:

luminosity (watts) = 600

distance (m) = 10