What is a passing factor of safety for sliding?

The commonly required minimum is FS ≥ 1.5 for sliding. Some codes require 1.5–2.0 depending on loading conditions and consequence of failure.

What is a passing factor of safety for overturning?

A minimum FS ≥ 2.0 for overturning is typical for gravity retaining walls under static loading per most geotechnical codes.

What is the bearing capacity factor of safety?

Bearing FS compares the allowable soil bearing capacity you supply against the maximum toe pressure produced by the wall. FS ≥ 3.0 is a common minimum for ultimate bearing capacity.

What assumptions does this calculator make?

Rankine active earth pressure (Ka), horizontal backfill, no wall friction (conservative), rectangular wall cross-section, and the Terzaghi general bearing capacity equation are assumed. It covers gravity walls only, not cantilever or anchored walls.

How is active earth pressure calculated?

Ka = tan²(45° − φ/2) using Rankine theory. Total active force Pa = 0.5 × Ka × γ × H² plus any surcharge contribution (Ka × q × H).

What units does this tool use?

All inputs are in SI: meters (m) for dimensions, kN/m³ for unit weights, kPa for surcharge and allowable bearing capacity, and degrees for the friction angle. Results are in kN/m and kPa.

Retaining Wall Stability Calculator

Name: Retaining Wall Stability Calculator
Availability: InStock
Author: Nham Vu

Enter wall geometry and soil properties to instantly check sliding, overturning, and bearing capacity factors of safety for a gravity retaining wall.

Wall & Soil Parameters

Wall Geometry

Wall Height H (m)

Base Width B (m)

Unit Weights

Wall γ_w (kN/m³)

Soil γ_s (kN/m³)

Friction Parameters

Soil friction φ (°)

Base friction μ

Loading & Soil Capacity

Surcharge q (kPa)

Allow. BC q_a (kPa)

Schematic

Enter parameters and click Calculate Stability

Sliding FS

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min 1.5

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Overturning FS

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min 2.0

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Bearing FS

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min 3.0

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Calculation Breakdown

Parameter	Value

Base Pressure Distribution

Heel Toe

Summary

Enter wall geometry and soil properties to instantly check sliding, overturning, and bearing capacity factors of safety for a gravity retaining wall.

How it works

Enter the wall height and base width.
Input the wall unit weight and retained soil unit weight.
Set the soil friction angle and base friction coefficient.
Optionally add a surcharge pressure on top of the retained soil.
Read the three factors of safety and the pass/fail status for each check.

Use cases

Preliminary sizing of a gravity or mass concrete retaining wall.
Checking an existing wall design against minimum FS requirements.
Teaching students the sliding and overturning stability concepts.
Quick sanity check before running a full geotechnical analysis.
Comparing different base widths or friction angles in seconds.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu