How to calculate gravel volume
Measure a rectangular area. U.S. customary inputs use feet for length and width and inches for depth, with results in cubic feet, cubic yards, pounds and U.S. short tons. Metric inputs use metres and centimetres or millimetres, with results in cubic metres, kilograms and tonnes. Choose an FHWA dry-loose-gravel estimating example or enter a density supplied for the material you plan to order.
Formulas and units
- Area: length (ft) × width (ft).
- Volume in cubic feet: area (sq ft) × depth (in) ÷ 12.
- Volume in cubic yards: cubic feet ÷ 27.
- Metric depth conversion: convert centimetres to metres by dividing by 100, or millimetres to metres by dividing by 1,000. Metric volume (m³) = length (m) × width (m) × depth (m).
- Other unit conversions: 1 in = 2.54 cm, 1 ft = 0.3048 m, and 1 lb = 0.45359237 kg.
- Metric weight: volume (m³) × bulk density (kg/m³) = kilograms; kilograms ÷ 1,000 = tonnes.
- Supplier density units: 1 US short ton/yd³ = 2,000 lb ÷ 27 ft³. 1 t/m³ = 1,000 kg/m³.
- Estimated pounds: cubic feet × selected bulk density (lb/ft³).
- Estimated US short tons: pounds ÷ 2,000.
- Optional extra allowance: base volume and base weight × (1 + entered allowance percentage ÷ 100). The base values remain visible. There is no universal allowance percentage; use project-specific guidance or leave it blank for 0%.
Calculations retain full precision until display. FHWA lists loose dry gravel at 2,700 lb/yd³ for uniformly graded material, 2,730 lb/yd³ for average gradation, and 2,770 lb/yd³ for well-graded material. Dividing by 27 gives the calculator's rounded presets of 100, 101.11, and 102.59 lb/ft³. The same table says its estimates are subject to variation; supplier data for the actual material is preferable. Source reviewed 15 October 2026.
Checked examples
20 × 10 ft, 4 in deep: 20 × 10 × (4 ÷ 12) = 66.67 cubic feet, or 2.47 cubic yards. At an assumed 100 lb/ft³, that is about 6,667 lb or 3.33 US short tons.
The same area, 8 in deep: volume is 133.33 cubic feet or 4.94 cubic yards. At the FHWA well-graded dry-gravel loose estimate of 2,770 lb/yd³ (about 102.59 lb/ft³), estimated weight is about 13,679 lb or 6.84 US short tons. An extra allowance changes the planning quantity, but it is not a measured compaction ratio.
Assumptions and limits
This tool models a level rectangular prism. Uneven ground, tapered layers, irregular boundaries, settlement and material loss need their own measurements or allowance. For an irregular site, split it into simpler sections and add their volumes. Depth should match the volume you are trying to fill; a finished compacted depth may require a separately determined loose placement depth.
Delivery weights, bag sizes, supplier minimums and order increments vary. The calculator does not select a truck, give a structural base design or determine a safe installation depth. Confirm your material, density and order quantity with the supplier. The example thickness controls are arithmetic inputs only; they do not specify a driveway, walkway, or aggregate-base design.
Related construction tools
Planning another aggregate or base project? Use the Concrete Calculator. Planning a paved surface above an aggregate base? Calculate the asphalt layer separately with the Asphalt Calculator. Read the gravel driveway guide for a worked planning example. Browse more options in Roofing & Construction.
Math runs in your browser; this tool does not upload your measurements to a calculation server. Found an issue? Report it to FivoTools.