Enter the total solar radiation on the surface during the period and the maximum theoretical radiation during the same period into the Calculator. The calculator will evaluate the Clearness Index.

## Clearness Index Formula

CI = TSR / MR

Variables:

- CI is the Clearness Index ()
- TSR is the total solar radiation on the surface during the period
- MR is the maximum theoretical radiation during the same period

To calculate Clearness Index, divide the total solar radiation on the surface by the maximum theoretical radiation during the period.

## How to Calculate Clearness Index?

The following steps outline how to calculate the Clearness Index.

- First, determine the total solar radiation on surface during period.
- Next, determine the maximum theoretical radiation during the same period.
- Next, gather the formula from above = CI = TSR / MR.
- Finally, calculate the Clearness Index.
- 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.

total solar radiation on surface during period = 1.7

maximum theoretical radiation during the same period = 2.8