Ground Temperature Calculator

Estimate undisturbed ground temperature at any depth and time of year.

Mean Annual Air Temp

°F

Seasonal Amplitude

°F

Depth

Day of Year

Soil Thermal Diffusivity

ft²/day

Tab to move between fields

Ground Temperature

52.5 °F

Stable Temp Depth

24.5 ft

≈ 4 adult heights

Deep Ground Temp55 °F

Damping Factor0.27

Phase Shift76 days

How to Use This Calculator

Enter your geographic latitude.
Set the depth below surface in meters.
Input the mean annual surface temperature for your region.
Review the undisturbed ground temperature at the specified depth.
Ground temperature stabilizes below ~10 m — this stable temperature is the heat source/sink for ground-loop systems.

How the result changes with Mean Annual Air Temp

Mean Annual Air Temp: Average annual surface air temperature.
Seasonal Amplitude: Temperature swing from the annual mean (half the range).
Depth: Depth below surface.
Day of Year: Day of year (1=Jan 1, 180=Jun 29, 365=Dec 31).
Soil Thermal Diffusivity: Soil thermal diffusivity (0.3 clay, 0.5 average, 1.0 rock).

Identify Input Parameters
4 parameters
Mean Annual Air Temp = 55, Seasonal Amplitude = 25, Depth = 10, Day of Year = 180 = 5 input(s) provided
Calculate Ground Temperature
Ground Temperature
52.5 = 52.5
Calculate Stable Temp Depth
Stable Temp Depth
24.5 = 24.5
Calculate Deep Ground Temp
Deep Ground Temp
55 = 55
Calculate Damping Factor
Damping Factor
0.269 = 0.269