How to measure your project area
For a simple rectangular area — a driveway, a path, a patio base — measure the length and width in feet and enter them directly. The calculator multiplies them together to get the square footage, then factors in depth to work out volume.
If your area is irregular — an L-shaped driveway, a patio with a bump-out, a bed that widens at one end — split it into two or more rectangles you can measure separately. Work out the gravel needed for each rectangle (or add the square footage of each piece together first), then sum the results.
For a circular area, such as a round fire pit surround or a circular planting bed, use the formula for the area of a circle: Area = π × r², where r is the radius (half the diameter). For example, a fire pit ring with a 10 ft diameter has a 5 ft radius, so its area is π × 5² ≈ 78.5 sq ft. Since this calculator asks for a length and a width, you can enter that square footage as the length and 1 as the width — length × width still equals the correct area.
The formula and a worked example
The math behind this calculator, in two steps:
Cubic yards = (Length ft × Width ft × (Depth in ÷ 12)) ÷ 27
Tons = Cubic yards × material density (tons per cubic yard)
Dividing by 27 converts cubic feet to cubic yards, since a cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet — and gravel is almost always priced and delivered by the cubic yard or by the ton.
Worked example: a driveway measuring 20 ft × 10 ft, filled 3 inches deep with crushed stone:
20 × 10 × (3 ÷ 12) = 50 cubic feet
50 ÷ 27 = 1.85 cubic yards
1.85 × 1.4 tons/yd³ ≈ 2.6 tons
Add the standard 5% waste allowance and that order grows to about 1.94 cubic yards, or roughly 2.7 tons — a small buffer that's usually cheaper than running short mid-project.
How deep should gravel be
The right depth depends on what the gravel is for. These are common starting points used in landscaping and DIY projects, not fixed rules — always check local guidance for your soil and climate:
- Walkways and garden paths: 2–3 inches is typically enough over a compacted base.
- Driveways: 4–6 inches total is common, often laid as two separate 2–3 inch layers that are compacted one at a time for a more stable surface than one deep, loose layer.
- Drainage (French drains, drain fields):a full 12 inches of clean gravel is a typical specification, since the gravel's job there is to let water pass through, not to bear weight.
If you're unsure, a local landscaper or your gravel supplier can confirm the right depth for your specific soil, frost depth, and expected load — foot traffic needs far less base than a car or truck.
Tons vs cubic yards
Cubic yards measure volume — how much physical space the material fills. Tonsmeasure weight. Suppliers usually quote both because delivery trucks are loaded and priced by weight, while you're actually trying to fill a three-dimensional space. The link between the two is density (tons per cubic yard), and it varies by material:
| Material | Approx. weight per yd³ | Tons per yd³ |
|---|---|---|
| Gravel / crushed stone | ≈ 2,800 lb | 1.40 |
| Pea gravel | ≈ 2,900 lb | 1.45 |
| Sand | ≈ 2,700 lb | 1.35 |
| Crushed limestone | ≈ 2,900 lb | 1.45 |
| Topsoil | ≈ 2,200 lb | 1.10 |
These are the densities used in this calculator. Treat them as reasonable averages rather than exact figures — moisture content makes a real difference, since wet sand or soil weighs noticeably more than the same material dry, and how tightly a load is packed in the truck also shifts the numbers slightly.