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# Design a Cantilever Retaining Wall to ACI 318-14

> Design cantilever retaining walls to ACI 318-14 and IBC 2018. An earlier code edition, kept for existing projects.

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    <div className="calc-details-head"><span className="calc-card-icon"><Icon icon="calculator" size={20} color="#0076d6" /></span><p className="calc-details-name">retainingWallCantileverUSA</p><a className="calc-details-run" href="https://app.calcs.com/new/sheet/retainingWallCantileverUSA">Run the calc</a></div>
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<div className="calc-answer">
  Design cantilever retaining walls to ACI 318-14 and IBC 2018. Rankine active earth pressure with overturning, sliding, and bearing checks, followed by stem and footing reinforcement design. For new projects, use the IBC 2021 or IBC 2024 version.
</div>

<Note>
  This calculator uses an earlier code edition (IBC 2018, ASCE 7-16). It stays available for existing projects. For new designs, check the [Calculator Library](/docs/calculators/us) for the current edition.
</Note>

## Method & scope

| Property       | Detail                                                                                                                                                                       |
| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| What it checks | Lateral earth pressure (Rankine active theory), Stability checks, Stem flexural and shear design (ACI 318-14, Cl. 21.2 and 22.5), Heel and toe design (ACI 318-14, Cl. 22.2) |

#### Calculation method

The Cantilever Retaining Wall (ACI 318-14) calculator designs freestanding cantilever retaining walls in reinforced concrete to IBC 2018 and ACI 318-14. Rankine active earth pressure theory is used with retained soil in the active state and passive soil at the toe for sliding resistance. No shear key is modeled.

##### Lateral earth pressure (Rankine active theory)

Active lateral earth pressure coefficient K\_a and passive coefficient K\_p are computed from the soil internal friction angle phi:

**K\_a = tan²(45°, phi/2)**
**K\_p = tan²(45° + phi/2)**

Lateral pressure varies triangularly with depth. Surcharge loads (dead and live) contribute a uniform lateral pressure component. The resulting lateral force H\_total and its line of action are used for the stability checks.

##### Stability checks

**Sliding**: Total horizontal force H\_total is compared to total resistance (base friction + passive soil at toe):

**FS\_sliding = F\_resist / H\_total ≥ 1.5**

**Overturning**: Restoring moment from soil and wall dead loads about the toe is compared to the overturning moment:

**FS\_overturn = M\_restore / M\_overturn ≥ 1.5**

**Bearing**: Maximum bearing pressure q\_max at the footing base (trapezoidal or triangular distribution depending on resultant eccentricity) is checked against the allowable bearing capacity q\_a.

##### Stem flexural and shear design (ACI 318-14, Cl. 21.2 and 22.5)

The governing moment M\_u,stem at the base of the stem and shear demand V\_u,stem are calculated from the factored lateral soil and surcharge loads per IBC 2018 LRFD combinations:

**utilization = M\_u,stem / (phi × M\_n,stem) ≤ 1.0**
**utilization = V\_u,stem / (phi × V\_n,stem) ≤ 1.0**

where phi = 0.90 for flexure and 0.75 for shear. Temperature and shrinkage reinforcement requirements per ACI 318-14 Cl. 24.4.3.2 are also reported.

##### Heel and toe design (ACI 318-14, Cl. 22.2)

Separate moment and shear checks are performed for the heel (resisting net upward pressure behind the stem) and toe (resisting upward bearing pressure in front of the stem):

**utilization = M\_u,heel / (phi × M\_n,heel) ≤ 1.0**
**utilization = M\_u,toe / (phi × M\_n,toe) ≤ 1.0**

##### Assumptions and scope

Backfill is flat with no slope. Only dead/live surcharge, wall self-weight, and soil loads are considered. No shear key is included. Wind and seismic loads are not modeled. Concrete detailing must be checked separately.

## How to use it

<Steps>
  <Step title="Open the calculator">
    Open it from **Run calc** in the About this calculator panel above.
  </Step>

  <Step title="Enter your inputs">
    Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See [Checks, References, Conditions and Assumptions](/docs/running-calculations/checking-results/checks-references-conditions-assumptions).
  </Step>

  <Step title="Review the results and export">
    Check the utilization of each governing check in the summary, then export a PDF report. See [Views and Export](/docs/running-calculations/exporting-reports/views-and-export).
  </Step>
</Steps>

## Common questions

<AccordionGroup>
  <Accordion title="What design standards does this calculator use?">
    The calculator references IBC 2018 for load combinations and ASCE 7-16 for load factors. Reinforced concrete stem and footing design follows ACI 318-14. Lateral earth pressure is calculated using Rankine active theory. This is the legacy code edition, for new projects use the IBC 2021 or IBC 2024 calculator version.
  </Accordion>

  <Accordion title="What are the key inputs?">
    Key inputs are wall height, stem thickness at base and top, toe length, heel length, footing thickness, soil unit weight, internal friction angle (phi), dead and live surcharge loads, concrete compressive strength (f'c), reinforcement bar size and spacing, and allowable bearing capacity. The calculator also accepts the passive soil parameters for sliding resistance.
  </Accordion>

  <Accordion title="What stability and strength checks does the calculator perform?">
    Stability checks include sliding (factor of safety ≥ 1.5 using base friction and passive soil resistance at the toe), overturning (factor of safety ≥ 1.5 about the toe), and maximum bearing pressure at the footing base versus allowable capacity. Strength checks cover flexural reinforcement and one-way shear in the stem, heel, and toe at their critical sections per ACI 318-14.
  </Accordion>

  <Accordion title="Does this calculator include a shear key?">
    No. This ACI 318-14 version does not include a shear key. If the sliding check fails without a shear key, use the IBC 2024 version which includes shear key design, or manually adjust wall dimensions until the sliding factor of safety is satisfied.
  </Accordion>

  <Accordion title="How does this version differ from the IBC 2021 and IBC 2024 versions?">
    This calculator is the legacy ACI 318-14 version, intended for projects already designed under that standard. The IBC 2021 version adds CMU stem design (TMS 402-16), Coulomb and EFP lateral earth pressure options, and seismic loads. The IBC 2024 version additionally includes a shear key, TMS 402-22 for CMU, ASCE 7-22 load combinations, and the latest IBC 2024 references. For new work, use the IBC 2024 version.
  </Accordion>
</AccordionGroup>

## Next steps

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