Enter the average rainfall, evaporation rate, and number of days into the calculator to determine the drought factor. This calculator helps in assessing the severity of drought conditions over a period of time.

## Drought Factor Formula

The following formula is used to calculate the drought factor:

DF = (E * D) - R

Variables:

- DF is the drought factor
- E is the evaporation rate (inches per day)
- D is the number of days
- R is the average rainfall (inches)

To calculate the drought factor, multiply the evaporation rate by the number of days and then subtract the average rainfall.

## What is a Drought Factor?

A drought factor is a numerical value that represents the severity of drought conditions in a specific area over a certain period of time. It takes into account the average rainfall and the rate of evaporation to help determine the water deficit. A higher drought factor indicates more severe drought conditions, which can impact agriculture, water supply, and the environment.

## How to Calculate Drought Factor?

The following steps outline how to calculate the Drought Factor:

- First, determine the evaporation rate (E) in inches per day.
- Next, determine the number of days (D) over which to measure the drought factor.
- Next, determine the average rainfall (R) in inches over the same period.
- Use the formula DF = (E * D) – R to calculate the Drought Factor (DF).
- 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.

Evaporation rate (E) = 0.2 inches per day

Number of days (D) = 30 days

Average rainfall (R) = 1 inch