MathBench

Gravel Calculator

Enter your area and depth to find how much gravel you need in cubic yards and US tons, with realistic densities for crushed stone, pea gravel, crusher run, and sand.

You need

—cubic yards (incl. allowance)
—US tons
—cubic feet
—area covered (ft²)

How this calculator works

Measure the length and width of the area in feet and decide how deep the gravel layer should be in inches. The calculator multiplies the three into a volume, adds an allowance for compaction and spillage, and converts the result into the two units gravel is sold in: cubic yards (landscape yards) and US tons (quarries). The material preset supplies the density that links those two numbers.

For an L-shaped or irregular area, split it into rectangles, run each one, and add the results. That's what an estimator would do on paper, and it avoids guessing at an "average" length and width.

The formula

Volume (ft³) = length × width × (depth ÷ 12)
Total ft³   = volume × (1 + allowance% ÷ 100)
Cubic yards = total ft³ ÷ 27
Tons        = cubic yards × density (t/yd³)

The preset densities are typical loose bulk values: crushed stone at about 105 lb/ft³ (1.42 t/yd³), pea gravel 96 lb/ft³ (1.30), crusher run 115 lb/ft³ (1.55), and dry sand 100 lb/ft³ (1.35). Rock density varies by quarry, so if your supplier quotes tons per yard for their product, choose "Custom density" and enter it.

Worked example

Say you're topping a 20 ft × 10 ft parking pad with 3 inches of ¾″ crushed stone, keeping the default 10% allowance:

  1. Area: 20 × 10 = 200 ft²
  2. Volume: 200 × (3 ÷ 12) = 50 ft³
  3. Add 10%: 50 × 1.10 = 55 ft³
  4. Cubic yards: 55 ÷ 27 = 2.04 yd³
  5. Tons: 2.04 × 1.42 = 2.89 tons

You'd order 2 cubic yards and pick up the remainder in bags, or ask the quarry for 3 tons and let the extra tighten up the low spots.

Assumptions & tips

  • Depth drives the order size. Going from 2 to 3 inches raises the whole order by 50%. Decide depth by use: 2–3″ decorative cover, 3–4″ walkway, 4″+ compacted base for anything that carries a vehicle.
  • Driveways are layers. A base of larger crushed stone compacted in lifts, then a surface course of smaller stone. Run this calculator once per layer with each material's depth.
  • Pea gravel rolls. Crushed stone locks. Rounded stone never firms up underfoot or under tires. Keep it to beds and borders, and use angular crushed stone where things need to stay put.
  • Put fabric under decorative gravel. A geotextile barrier keeps the stone from sinking into the soil and the weeds from coming through it. It's the difference between a 10-year and a 2-year installation.
  • Check the delivery minimum. Many quarries have a 1-ton minimum and price small loads steeply. Below about half a ton, bagged gravel from the box store often wins on total cost.

Frequently asked questions

How many tons is a cubic yard of gravel?

Most construction gravel weighs about 1.4 US tons per cubic yard in its loose state, roughly 2,800 pounds. Lighter materials like pea gravel run closer to 1.3 tons per yard, while denser crusher run with fines can reach 1.55 tons. If your supplier quotes a different figure for their material, use it: local rock varies.

How deep should gravel be?

For a decorative ground cover over fabric, 2 to 3 inches is enough. A walkway wants 3 to 4 inches. A gravel driveway is a layered system: 4 inches or more of compacted base stone with 2 to 3 inches of surface gravel on top, and each layer should be compacted separately. Thin layers over bare soil disappear into the ground within a season.

Should I order gravel by the yard or by the ton?

Whichever way your supplier sells it: quarries usually price by the ton, landscape yards often by the cubic yard. This calculator gives you both numbers for the same pile, so you can compare quotes directly. The two are linked by density: tons equals yards times tons-per-yard for that material.

Sources

  1. ASTM C29/C29M-23: Standard Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate. ASTM International, 2023. astm.orgDefines how bulk density is measured in both the loose and the compacted condition, and states that bulk density is used for the mass-to-volume conversions in aggregate purchase agreements: the basis for selling gravel by the ton against a cubic-yard volume. The method also cautions that the compaction of a stockpile or a loaded truck cannot be inferred from the test, so this page asks you to use your own supplier's figure.
  2. Gravel Roads Construction and Maintenance Guide. U.S. Department of Transportation, Federal Highway Administration, 2015. fhwa.dot.govSection 3.19 warns that quantities figured from loose stockpile volume ignore the shrinkage of ordinary compaction, which is what the compaction allowance covers; section 3.4 explains why fractured crushed stone embeds and resists movement where rounded natural stone does not.
  3. Earth and Aggregate Surfacing Design Guide, Agricultural Engineering Technical Note No. AEN-4. USDA Natural Resources Conservation Service, 2017. nrcs.usda.govSets out the base-course-plus-surface-course structure for aggregate driveways behind the advice to run the calculator once per layer.

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