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Earth Pressure Calculator

Work out earth pressure instantly with clear inputs, formula shown and shareable results.

About Earth Pressure Calculator

Rankine's theory gives the active coefficient as (1 - sin phi) / (1 + sin phi) and the passive as its reciprocal. Active pressure increases linearly with depth, so the soil thrust is the triangular area 0.5 Ka gamma H², while a uniform surcharge adds a rectangular Ka q H acting at mid-height.

Formulas

Rankine coefficients

Ka = (1 - sin phi) / (1 + sin phi); Kp = 1 / Ka

Thrust

Pa = 0.5 Ka gamma H² + Ka q H

Worked example

With the default values below, Earth Pressure Calculator returns Total active thrust per metre of 61.33. Change any input above and every figure here is recalculated in your browser.

Inputs used

Wall heightminimum 0.1 m
4 m
Soil unit weightminimum 5 kN/m³
18 kN/m³
Angle of internal frictionaccepts 1–45 °
30 °
Surchargeminimum 0 kPa
10 kPa

Results

Total active thrust per metre
61.33 kN/m
Active coefficient Ka
0.3333
Active pressure at base
27.33 kPa
Passive coefficient Kp
3.000

Step by step

  1. 1Values used
  2. 2Rankine coefficients
  3. 3Thrust
  4. 4Total active thrust per metre= 61.33 kN/m
  5. 5Active coefficient Ka= 0.3333
  6. 6Active pressure at base= 27.33 kPa
  7. 7Passive coefficient Kp= 3.000

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Preliminary estimate only. Earth pressure assessment must be carried out by a qualified geotechnical engineer using site-specific soil parameters and wall movement assumptions.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Earth pressure assessment must be carried out by a qualified geotechnical engineer using site-specific soil parameters and wall movement assumptions.

Frequently Asked Questions

How is the Earth Pressure figure worked out?

Ka = (1 - sin phi) / (1 + sin phi); Kp = 1 / Ka. Rankine's theory gives the active coefficient as (1 - sin phi) / (1 + sin phi) and the passive as its reciprocal.

When is at-rest pressure used instead?

When the wall cannot rotate, such as a basement wall braced by floors. K0, approximately 1 - sin phi, is larger than Ka and gives a bigger thrust.

What values do I need to enter?

This calculator takes 4 inputs: Wall height, Soil unit weight, Angle of internal friction, Surcharge. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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