How to use the gravel calculator
- Choose the shape and enter the size of the area, or enter the area directly.
- Enter the depth of gravel: 2 in (5 cm) for paths, 3–4 in (7.5–10 cm) for patios and parking, more for driveways.
- Pick the material. If your supplier gives a weight per yard or per cubic metre, choose “Other” and enter it.
- Keep 5–10% extra for compaction, and enter a price per ton or per yard to estimate cost.
Gravel formula
Volume (yd³) = Length (ft) × Width (ft) × Depth (in) ÷ 12 ÷ 27 Weight (tons) = Volume (yd³) × Density (tons per yd³) Metric: Volume (m³) = L × W × D (m); Weight (t) = m³ × t/m³
Worked example
A 20 × 10 ft patio base, 4 inches deep, pea gravel:
- Volume = 20 × 10 × 4 ÷ 12 = 66.7 ft³ ÷ 27 = 2.47 yd³
- Weight = 2.47 × 1.35 = 3.33 US tons (3.02 tonnes)
- With 5% extra: 3.5 tons — at $45 per ton, about $158 before delivery
Typical gravel weights
| Material | lb per yd³ | tons per yd³ | kg per m³ |
|---|---|---|---|
| Pea gravel (⅜ in) | ≈ 2,700 | 1.35 | ≈ 1,600 |
| Coarse gravel (¾ in) | ≈ 2,565 | 1.28 | ≈ 1,520 |
Weights vary with stone type, size and moisture. Ask your supplier for their figure and use the custom density option for the most accurate result.
Gravel depth guide
| Project | Depth |
|---|---|
| Garden path, decorative cover | 2 in (5 cm) |
| Patio or shed base (under pavers or slab) | 4 in (10 cm) compacted |
| Parking area on firm ground | 4–6 in (10–15 cm) |
| New driveway on soft ground | 8–12 in (20–30 cm) in layers |
| French drain / drainage trench | Fill the trench depth |
Which gravel should I choose?
Pea gravel is small and rounded, comfortable to walk on and good for paths, play areas and between stepping stones, but it rolls underfoot and does not lock together, so it is a poor choice for slopes and driveways. Crushed stone (angular, often ¾ in / 20 mm) interlocks when compacted, which makes it the standard base for driveways, patios and sheds. Crusher run (also called dense grade, MOT Type 1 in the UK or GSB in India) mixes stone with fines and compacts very hard — ideal as a sub-base. River rock and larger cobbles are mainly decorative and for drainage swales.
Tips
- Lay landscape fabric under decorative gravel to stop weeds and stop the stone sinking into soil.
- Compact in layers of 2–3 in (5–7.5 cm) with a plate compactor for driveways and bases.
- Use edging to keep gravel off lawns and beds.
- Check delivery access: a tipper truck needs firm ground and overhead clearance; one load is often 10–15 tons.