Inputs
Choose units and enter geometry, soil, and design targets.
US / Imperial
Switch resets placeholders only.
ft
Exposed height above base level (embed below grade separately).
ft
Front bury to resist toe scour and frost.
ft
ft
Use average thickness if tapered.
ft
ft
pcf
deg
psf
Uniform surcharge on backfill surface.
If yes, adds hydrostatic pressure.
pcf
—
Interface friction soil–base.
psf
How to use this calculator
- Select units, wall type, geometry, and soil parameters.
- Enter surcharge if applicable and choose whether water acts behind the wall.
- Choose interface friction, bearing capacity, and safety factor targets.
- Press Calculate. Review lateral force, moments, and stability checks.
- Use the k-factor suggestion (B ≈ k·H) to iterate base geometry.
- Export results to CSV or PDF for submittals and recordkeeping.
Important: This tool provides preliminary design checks. Always verify with local codes, groundwater, seismic, and detailed geotechnical recommendations.
Formulas used (Rankine active; level backfill)
Backfill friction angle φ (deg). Active earth pressure coefficient Ka = tan²(45° − φ/2).
Triangular earth pressure from soil self-weight: Ptri = 0.5 · Ka · γ · H² acting at H/3 above base.
Rectangular earth pressure from surcharge q: Prect = Ka · q · H acting at H/2.
Hydrostatic component (if selected): Pw = 0.5 · γw · H² acting at H/3.
Total lateral force P = Ptri + Prect + Pw. Resultant elevation ȳ found by moment of areas.
Sliding check: FSslide = μ · W / P, where W is sum of vertical weights.
Overturning check about toe: FSOT = Mresist / MOT using weights and lateral force arms.
Bearing: resultant eccentricity e = (Mresist − MOT)/W. No tension if |e| ≤ B/6. Stresses qmax,min = (W/B)·(1 ± 6e/B).
Example scenarios (load to experiment)
| Case | Units | H | φ | γ | q | Toe | Stem | Heel | Base | γc | μ | qallow |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Typical residential, granular backfill | US | 8 | 32° | 120 | 250 | 2.0 | 1.0 | 3.5 | 1.0 | 150 | 0.55 | 3000 |
| Light commercial, metric inputs | SI | 2.4 | 34° | 19 | 12 | 0.6 | 0.3 | 1.0 | 0.3 | 24 | 0.55 | 180 |
| Taller wall with surcharge and water | US | 10 | 30° | 125 | 400 | 2.5 | 1.1 | 4.2 | 1.1 | 150 | 0.50 | 2500 |
Click a row to load values into the form.
Results (per unit length out of plane)
Summary
Total base width B—
Suggested B ≈ k·H—
Active pressure coefficient Ka—
Total lateral force P—
Resultant height ȳ above base—
Sum of vertical weights W—
Sliding factor of safety—
Overturning factor of safety—
Eccentricity e—
qmax at toe—
qmin at heel—
Check vs qallow—
FAQs
Which earth pressure method is used?
Rankine active pressure for level backfill is used for simplicity. For sloped backfill or wall friction, consider Coulomb or numerical methods.
Can I account for water behind the wall?
Yes. Toggle “Water behind wall?” to include hydrostatic pressure with unit weight of water appropriate to the selected unit system.
How is sliding resistance computed?
Base sliding resistance equals μ times total vertical weight of wall and any included soil over the heel; passive pressure in front of toe is conservatively neglected.
Are geogrid layers designed here?
No. This calculator suggests stability for the gravity system. Geogrid reinforcement for SRW walls requires manufacturer software or detailed design procedures.
Is this acceptable for final design?
Use for preliminary sizing and checks only. Final design must follow applicable codes, site geotechnical data, drainage design, and professional engineering judgment.