How to use the gravel calculator
- Choose a rectangle or circle and enter its dimensions. For irregular shapes, add up several rectangles.
- Enter the finished depth of gravel.
- Set a compaction and waste allowance. Loose gravel settles when compacted, so you need more than the finished volume.
- Check the density (tons per cubic yard) with your supplier, then optionally add a price per ton or per cubic yard.
How the calculation works
Volume is area × depth. The allowance percentage is added, and the volume is converted to cubic yards (÷ 27 from cubic feet) and cubic meters. Weight is the volume in cubic yards multiplied by the bulk density in short tons (2,000 lb) per cubic yard.
Density matters: gravel is a mix of stone and air gaps, and its weight per yard depends on the rock type, particle size and moisture. The default of 1.4 tons/yd³ is a typical mid-range figure, not a property of any specific product.
Formula
- a
- Compaction and waste allowance as a decimal
- density
- Bulk density in short tons per cubic yard
Worked examples
20 × 10 ft area, 4 in deep
Volume = 20 × 10 × (4 ÷ 12) = 66.67 ft³ = 2.47 yd³. With 10% allowance: 2.72 yd³.
At 1.4 tons/yd³: 2.72 × 1.4 = 3.80 tons.
Circular fire-pit area 12 ft across, 3 in deep
Area = π × 6² = 113.1 ft². Volume = 113.1 × 0.25 = 28.27 ft³ = 1.05 yd³; with 10% allowance 1.15 yd³, about 1.61 tons.
Assumptions and limitations
- Density varies by material, gradation and moisture (wet gravel is heavier). Use your supplier’s figure for accurate tonnage.
- The compaction allowance is an estimate; dense-graded base material can compact by 15-25% or more.
- Uneven excavation depth changes the volume. Measure depth in several places and use an average.
Frequently asked questions
How many tons of gravel are in a cubic yard?
Typically about 1.3 to 1.7 short tons, depending on the stone and its size. 1.4 tons is a common planning figure.
How much area does a ton of gravel cover?
At 1.4 tons/yd³, one ton is about 19.3 ft³. Spread 2 in deep it covers roughly 116 sq ft; at 4 in deep about 58 sq ft.
What is the difference between this and the stone calculator?
This calculator is a general gravel estimator with a single editable density. The stone calculator includes material presets for crushed stone, base and decorative stone with typical densities.
Sources and references
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI).