Geothermal Gradient Calculator

Calculate temperature at depth from the geothermal gradient.

Surface Temperature

°F

Geothermal Gradient

°C/km

Target Depth

Heat Flow

mW/m²

Rock Conductivity

W/(m·K)

Tab to move between fields

Temperature at Depth

105 °C

Depth for 150°C

4.5 km

≈ 14 Eiffel Towers

Gradient from Heat Flow26 °C/km

Depth for 200°C6.2 km

Resource Grade (1=High)2

Temp From Heat Flow93

How to Use This Calculator

Enter the surface temperature at your location in °C.
Set the depth of interest in meters.
Input the local geothermal gradient in °C/km (global average ~25–30 °C/km).
Review the estimated temperature at depth.
Deep direct-use and EGS projects require temperatures above 150 °C — check regional gradient maps.

How the result changes with Geothermal Gradient

Surface Temperature: Mean annual surface temperature.
Geothermal Gradient: Temperature increase per kilometer of depth (25-30 is typical).
Target Depth: Depth of interest in kilometers.
Heat Flow: Surface heat flow (65 mW/m² is average continental).
Rock Conductivity: Thermal conductivity of the rock formation.

Identify Input Parameters
4 parameters
Surface Temperature = 15, Geothermal Gradient = 30, Target Depth = 3, Heat Flow = 65 = 5 input(s) provided
Calculate Temperature at Depth
Temperature at Depth
105 = 105
Calculate Depth for 150°C
Depth for 150°C
4.5 = 4.5
Calculate Gradient from Heat Flow
Gradient from Heat Flow
26 = 26
Calculate Depth for 200°C
Depth for 200°C
6.2 = 6.2