Concrete Calculator
For the sidewalk or patio slab you pour on top.
Driveways, paths & drainage
How much gravel do I need?
Enter the area length, width and gravel depth, choose your stone, and the gravel calculator returns volume in cubic yards and weight in tons. A 20 × 20 ft driveway topped at 4 inches needs about 4.9 cubic yards ≈ 7.4 tons of crushed stone — order in half-ton steps for easy spreading.
Think of gravel orders in layers: coarse base stone (#3/#4) for structural depth, then smaller #57 or #89 crushed stone on top for the finished surface — with geotextile fabric underneath to keep the rock from sinking into the soil. Add each project area separately (driveway, path, drainage trench), choose your stone type and depth, and the calculator converts the volume into cubic yards and weight into tons, with the metric tonnes equivalent shown as well.
Frequently asked questions
How many tons of gravel do I need for a 20×20 area?
A 20 × 20 ft area (400 sq ft) at 4 inches holds 4.94 cu yd. Crushed stone weighs about 1.5 tons per yard, so that's roughly 7.4 tons — order 7.5 tons. Reduce depth to 2 inches and the same area needs about 3.7 tons.
How deep should a gravel driveway be?
Build driveways in two layers: a 4-inch base of large crushed stone (#3/#4) compacted, then a 2–4 inch top of #57 or #89 crushed stone. The total 6–8 inches keeps the surface stable under vehicle weight.
How much area does one ton of gravel cover?
One ton of crushed stone (≈0.67 cu yd) covers about 120 sq ft at 2 inches deep, 80 sq ft at 3 inches, or 60 sq ft at 4 inches. The exact number depends on the stone's density.
Pea gravel or crushed stone — which is better for a path?
Pea gravel is round and comfortable underfoot, great for decorative paths, but it shifts and needs edging. Angular crushed stone locks together and stays put — better for driveways and heavily walked paths.
How do I order gravel by cubic yards or by the ton?
Calculate volume first (length × width × depth in yards), then multiply by the stone's density — crushed stone runs about 1.4–1.6 tons per cubic yard. This calculator shows both numbers and suggests rounding up in half-ton steps so the delivery truck never comes up short.
How much gravel do I need under patio pavers?
Plan on a compacted crushed-stone base about 4–6 inches deep under pavers, topped with 1 inch of leveling sand. For a 10 × 20 ft patio that is roughly 3.1 cubic yards — about 4.5 tons of base stone. Enter your own footprint and depth here to get the exact figure.
Gravel Calculator
Imperial
ft
ft
inches
Enter your area size to see the result.
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tons
Suppliers sell by the cubic yard or ton — weights are typical densities for dry material.
How it works
How to use this gravel calculator
1Measure the footprint
Length × width in feet for the area you are covering. A driveway is the strip between the street and garage; a path is usually 3–4 ft wide.
- For a curved path, measure the centerline length × width.
- Add 2 ft on each side at the street end of a driveway for turning.
- Plan on hand-spreading — deeper loads are harder to move.
2Choose the depth
Depth depends on use — the depth guide table below shows the recommended total depth for paths, driveways and drainage.
- Walkways & patios: 2–3 in.
- Driveways: 4 in top coat over a compacted base.
- French drains: fill the whole trench around the pipe.
3Match the density
Each stone weighs differently — that's why the calculator asks for material. Pea gravel (1.4 t/yd³) is lighter than decomposed granite (1.7 t/yd³), so tonnage changes even when volume doesn't. When ordering by weight, round up to the nearest half-ton.
The math
Gravel quantity formula
Cubic feet = length × width × (depth ÷ 12) • Cubic yards = cubic feet ÷ 27
Tons = cubic yards × material density (t / yd³)
Worked example — 20 × 20 ft area at 4 in, crushed stone #57 at 1.5 t/yd³:
Volume: 400 × 0.333 = 133.3 cu ft = 4.94 cu yd; × 1.5 = 7.4 tons → order ~7.5 tons.
Volume: 400 × 0.333 = 133.3 cu ft = 4.94 cu yd; × 1.5 = 7.4 tons → order ~7.5 tons.
Depth guide
Recommended gravel depth by project
| Project | Depth | Best material |
|---|---|---|
| Walkway / patio | 2–3 in | Pea gravel or decomposed granite |
| Driveway top coat | 4 in (over 4 in base) | Crushed stone #57 |
| Driveway base | 4 in | Crushed stone #3 or #4 (large) |
| French drain / trench | Fill to grade | Clean 1–2 in crushed gravel |
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