Enter the actual vapor density and the saturation vapor density into the calculator to determine the relative humidity.

- Specific Humidity Calculator
- Wet Bulb Calculator
- Water Vapor Pressure Calculator
- Vapor Pressure Calculator (Solvent/Solution)
- Humidity Ratio Calculator
- VPD (Vapor Pressure Deficit) Calculator
- Discomfort Index Calculator

## Relative Humidity Formula

The following formula is used to calculate relative humidity.

RH = VDa / VDs * 100

- Where RH is the relative humidity (%)
- VDa is the actual vapor density (g/m^3)
- VDs is the saturation vapor density (g/m^3)

To calculate relative humidity, divide the actual vapor density by the saturation vapor density.

## Relative Humidity Definition

The relative humidity is the ratio of the vapor density to the saturation density of water in the air.

## Relative Humidity Example

How to calculate a relative humidity?

**First, determine the vapor density.**Measure the water vapor density.

**Next, determine the saturation density.**Measure the saturation water vapor density.

**Finally, calculate the relative humidity.**Calculate the relative humidity using the formula above.

## FAQ

**What is a relative humidity?**

The relative humidity is a ratio of vapor density to saturation vapor density. It’s a measure of how much water vapor air can hold compared to how much water vapor it takes to saturate the air at any given temperature.

**What is a saturated air?**

Saturated air is one at 100% relative humidity and that at the specific temperature it cannot hold any more water vapor.