Enter the air temperature and dew point temperature into the calculator to estimate the cloud base height (above ground level, AGL). You can also estimate cloud base from temperature and relative humidity, from dew point spread, or by parsing a METAR.

Cloud Height Calculator

Temp + Dew Point
Temp + RH
Dewpoint Spread
From METAR

Estimate cloud base from temperature and dew point.

Cloud Height Formula

The following rule-of-thumb formula is used to estimate the cloud base height above ground level (AGL) from the temperature–dew point spread.

\begin{aligned}
H_{AGL}(\text{ft}) &\approx 222\,(T-T_d)\quad (T,T_d\text{ in }^\circ\mathrm{F})\\
&\approx 400\,(T-T_d)\quad (T,T_d\text{ in }^\circ\mathrm{C})
\end{aligned}

Variables:

  • HAGL is the estimated cloud base height above ground level (feet)
  • T is the air temperature (°F, or °C in the alternate form)
  • Td is the dew point temperature (°F, or °C in the alternate form)

To estimate the cloud base height, subtract the dew point temperature from the air temperature (the “spread”), then multiply by 222 (if using °F) or 400 (if using °C). This gives an approximate cloud base in feet AGL near the observation point; add field/station elevation to estimate the cloud base altitude MSL.

What is a Cloud Height?

Cloud height (often called cloud base height) refers to the vertical distance from the ground at a given location to the base or bottom of a cloud (AGL). It is usually reported in feet or meters. In aviation, cloud bases and ceilings are important for flight planning and safety. If you need an altitude above mean sea level (MSL), you can add the local ground/station elevation to the AGL cloud base.

How to Calculate Cloud Height?

The following steps outline how to calculate the Cloud Height using the given formula:

  1. First, determine the air temperature (T) in °F.
  2. Next, determine the dew point temperature (Td) in °F.
  3. Subtract the dew point temperature (Td) from the temperature (T) to get the difference.
  4. Multiply the difference by 222 (approx.).
  5. Finally, calculate the estimated cloud base height (H) in feet AGL.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Temperature (T) = 75°F

Dew Point Temperature (Td) = 60°F