Earth Pressure Coefficients

Developer: Rey Villa, M.S., P.E.

About and FAQ


This is a web app for geotechnical engineering that calculates the following lateral earth pressure coefficients for granular soils that are required for a geotech to perform retaining wall design:

  • Active earth pressure coefficient, Ka (Rankine & Coulomb)
  • Passive earth pressure coefficient, Kp (Rankine & Coulomb)
  • At-Rest earth pressure coefficient, Ko (Mayne & Kulhawy)

This web app does not perform retaining wall design. Rather, it calculates coefficients that are needed to determine the lateral earth pressure that can act on retaining walls. It is up to the geotechnical engineer or structural engineer to determine which coefficient applies depending on the retaining wall, retainied earth material, geometry, and other factors.

Supported Browsers

Google Chrome, Mozilla Firefox and Safari.

What is a Web App?

A web app is an application that runs on a remote server (i.e. cloud) and is an alternative to conventional software for geotech that has to be installed on your computer. You don't have to worry about installing any geotechnical software any computer. All you need is an active internet connection. Easy right?

Why Not Software?

Because web apps are awesome! They are very flexible, can be used on most computers/devices without installation and web apps are the future! Let's get the civil engineering profession up to date!

Where do I get the soil parameter input values?

If you don't know the answer to this question, you shouldn't be using this web app. This is simply a tool that calculates coefficients based on user input. Refer to an civil engineer that specializes in the field of geotech for guidance.


Free. Why? Because we can. Developing these web apps are extremely fun and challenging. Also, it's a great way to learn more about our geotechnical engineering profession.

Retaining Wall

If you see this message, please update your browser to Google Chrome!

Wall Geometry:

  • β : Retaining Wall Inclination (Degrees)
  • α : Soil Backfill Angle (Degrees)

Granular Soil Properties:

  • φ: Drained Soil Friction Angle (Degrees)
  • δ: Soil-Wall Friction Angle (Degrees)
  • OCR : Soil Overconsolidation Ratio

Geotechnical References & Equations


Das, Braja (2006), "Principles of Foundation Engineering, 6th ed."

At-Rest Earth Pressure Coefficient, Ko
At-Rest Earth Pressure

Mayne & Kulhawy, 1982

Rankine Active Earth Pressure Coefficient, Ka
Rankine Active Earth Pressure
Rankine Passive Earth Pressure Coefficient, Kp
Rankine Active Earth Pressure
Coulomb Active Earth Pressure Coefficient, Ka-c
Coulomb Active Earth Pressure
Coulomb Passive Earth Pressure Coefficient, Kp-c
Coulomb Passive Earth Pressure