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Foundation Excavation Calculator

Calculate foundation excavation bank volume in cubic yards and loose haulage volume — adjust for swell and waste. Enter dimensions, select units and add waste to get instant, supplier-ready numbers.

1. Measurements & Dimensions

3. Optional Material Cost

FOUNDATION EXCAVATION CALCULATOR ESTIMATE
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Enter dimensions above to calculate

Calculation Breakdown & StepsFormula: Bank volume = length × width × depth; loose volume = bank volume × (1 + swell / 100).
  1. Enter values to see step-by-step substitution.

    Engineering Assumptions:

    • Vertical rectangular excavation. Sloped sides, working room, overbreak and irregular ground need separate measured allowances.
    • The cost basis is bank cubic yards. Loose haulage volumes are shown separately. Swell is not a second waste allowance.
    VISUAL GUIDE — FOUNDATION EXCAVATION CALCULATORfoundation · foundation-excavation-calculator

    TOP VIEW — Length × Width

    Foundation Excavation Calculator topLength 15ftWidthFoundation Excavation15×15 = 225 ft²

    SECTION — Excavation depth 10ft

    Foundation Excavation Calculator sectionFoundation Excavation 10ft10"Bank volume = length × width × depth; loose volume = bank volume × (1 + swell / 100). · +7% → 7.43 yd³
    Foundation Excavation Calculator — Bank volume = length × width × depth; loose volume = bank volume × (1 + swell / 100). · example 15×15 @10ft = 187.5 ft³ (6.94 yd³) → 7.43 yd³ with 7% waste · foundation-excavation-calculator

    What Is This Calculator?

    The Foundation Excavation Calculator — Estimates foundation excavation, footings and walls for US homes — volume, concrete and cost.

    What Does It Calculate?

    • Footing volume in cubic yards
    • Foundation wall area and concrete
    • Excavation volume with waste

    How to Use the Calculator

    1. Measure Trench 20 ft x 2 ft x 4 ft deep — use feet for length/width and inches for thickness where typical.
    2. Enter values and select units. The calculator converts to feet before calculating (inches /12, yards x3).
    3. Adjust waste % and optional price, then click Calculate. Results show with waste included.
    4. Use Reset to clear and try another size.

    Formula & Engineering Methodology

    Bank volume = length × width × depth; loose volume = bank volume × (1 + swell / 100).

    • Volume — Cubic yards with swell 1.2x
    • Depth — Feet or inches

    All units convert to exact standard engineering dimensions (NIST SP 811) before calculation to ensure consistency between US Customary and Metric measurements.

    Worked Example

    Example: Trench 20 ft x 2 ft x 4 ft deep

    STEPVALUE
    Volume ft320*2*4 =160 ft3
    Yards160/27 =5.93 yd3
    With swell 1.2x7.11 yd3

    Construction Information

    Material: Footings 8–12 in thick, walls 8 in. Concrete 3000–4000 psi. Footing below frost line per local code.

    Soil swells 15-25% when dug (1.2x). Clay 1.6 t/yd3, call 811.

    Material Information

    Footings 8–12 in thick, walls 8 in. Concrete 3000–4000 psi. Footing below frost line per local code.

    Waste & Overages

    Add 10% for over-excavation and slough — trench sides cave.

    Practical Tips

    • Call 811 before digging
    • Keep footings on undisturbed soil or compacted fill

    Common Mistakes

    • Shallow footings above frost line — heave
    • Not adding extra for footing flares

    Assumptions & Engineering References

    • Vertical rectangular excavation. Sloped sides, working room, overbreak and irregular ground need separate measured allowances.
    • The cost basis is bank cubic yards. Loose haulage volumes are shown separately. Swell is not a second waste allowance.

    This calculator provides an estimate based on your inputs. Actual requirements vary by site, material and installation. For code-regulated or load-bearing work, consult a qualified professional.

    Calculations run 100% in your browser — zero tracking of your dimensions or input data.

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    Frequently asked questions

    What does the Foundation Excavation Calculator calculate?

    The Foundation Excavation Calculator estimates foundation excavation quantity for US jobs — Footing volume in cubic yards, Foundation wall area and concrete, Excavation volume with waste. Enter dimensions, choose units, add waste and price to get instant results.

    How do I measure for foundation excavation?

    Measure trench 20 ft x 2 ft x 4 ft deep on site. Use the unit selectors — the tool converts inches→feet (÷12) and yards→feet (×3) before math. For non-rectangular, split into rectangles and add.

    How much waste should I add?

    Add 10% for over-excavation and slough — trench sides cave.

    How accurate is this foundation excavation estimate?

    Math is exact for your inputs. Actual needs vary by site, material and installation. Add 5–10% waste for rectangular, 10–15% for irregular.

    About Calculator Street

    Built by Vipul Otari for US homeowners & contractors. Calculator inputs are processed in your browser. Estimates depend on your measurements, product specifications and the assumptions shown on this page. Confirm order quantities with your supplier and structural requirements with your project designer. Page updated: 2026-09-11.

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