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Worked example

Gravel for a 10 × 20 Patio Base

Estimate compacted base volume and illustrative tonnage for a 200 sq ft patio at 4 in depth.

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The practical starting point

The planning figures are 2.47 compacted cu yd and about 3.8 tons under the stated placeholder density. Replace that density with the local quarry conversion before ordering. This compacted gravel example uses these stated inputs: Base footprint: 10 ft × 20 ft; Compacted depth: 4 in; Illustrative density: 1.4 tons per cu yd; allowance: 10%. Change any one of them and rerun the arithmetic rather than treating the rounded answer as a universal order.

STEP BY STEP

A worked calculation you can check

  1. 01

    Write the measured scope

    Gravel for a 10 × 20 Patio Base begins with a visible, checkable scope: Base footprint: 10 ft × 20 ft; Compacted depth: 4 in; Illustrative density: 1.4 tons per cu yd; allowance: 10%. Keep the units beside every dimension so feet, inches, square feet and purchase coverage cannot be mixed silently.

  2. 02

    Run the unrounded arithmetic

    Volume is 10 × 20 × 4 ÷ 12 = 66.67 cu ft, or 2.47 cu yd. At 1.4 tons per yard and 10% allowance, 2.47 × 1.4 × 1.10 = 3.80 tons.

  3. 03

    Convert to supplier cubic yards or tons

    The planning figures are 2.47 compacted cu yd and about 3.8 tons under the stated placeholder density. Replace that density with the local quarry conversion before ordering. Round only after the final division, then reconcile the number with the sizes or increments the supplier actually sells.

  4. 04

    Test the result against the real project

    Confirm whether the aggregate quote describes loose truck volume or delivered weight and how much material is expected to compact into the four-inch layer. Use the supplier's bulk density and compaction recommendation for the exact aggregate instead of treating every gravel product as 1.4 tons per yard.

Worked inputs and arithmetic

Estimate compacted base volume and illustrative tonnage for a 200 sq ft patio at 4 in depth.

Volume is 10 × 20 × 4 ÷ 12 = 66.67 cu ft, or 2.47 cu yd. At 1.4 tons per yard and 10% allowance, 2.47 × 1.4 × 1.10 = 3.80 tons.

  • Base footprint: 10 ft × 20 ft
  • Compacted depth: 4 in
  • Illustrative density: 1.4 tons per cu yd; allowance: 10%

What can change this answer

Confirm whether the aggregate quote describes loose truck volume or delivered weight and how much material is expected to compact into the four-inch layer.

Subgrade, drainage, separation fabric, layer gradation and vehicle loading determine whether the chosen section is suitable.

  • Edge support can require the base to extend beyond the visible patio.
  • Saturated or weak subgrade may need undercutting rather than simply more aggregate.
  • A 6 in design would increase this example to 3.70 cu yd before allowance.

Turn the example into your own order

Open the Gravel Calculator, enter the dimensions from your site and replace the example coverage, yield, density, waste, package size or capacity with the exact value that applies to your compacted gravel choice. Save the first measured result before testing alternatives so the reason for every change remains visible.

Use the supplier's bulk density and compaction recommendation for the exact aggregate instead of treating every gravel product as 1.4 tons per yard. Subgrade, drainage, separation fabric, layer gradation and vehicle loading determine whether the chosen section is suitable.

COMMON ERRORS

What usually throws the order off

  • Copying the gravel for a 10 × 20 patio base result without matching all three inputs
  • Rounding every dimension before the compacted gravel calculation
  • Ignoring the buyable supplier cubic yards or tons after the arithmetic
  • Using extra compacted gravel as a substitute for the site and product checks

Frequently asked questions

Can I use the gravel for a 10 × 20 patio base answer for a slightly different project?

Use it only as a reasonableness check. Enter your own dimensions and assumptions in the Gravel Calculator; small changes in depth, height, repeat, pitch, coverage or capacity adjustment can alter the rounded purchase unit.

Why does the final number round up?

Supplier cubic yards or tons are not normally purchased as the exact decimal produced by division. Round the final requirement to the next available unit, then document any remaining matching stock instead of hiding it as vague waste.

What should I verify before buying?

Use the supplier's bulk density and compaction recommendation for the exact aggregate instead of treating every gravel product as 1.4 tons per yard. Also verify this project boundary: Subgrade, drainage, separation fabric, layer gradation and vehicle loading determine whether the chosen section is suitable.

Technical references

These references support the measurement and planning method. Product instructions, the site and applicable local requirements control the final installation.