How to use the gravel calculator
- Choose feet and inches or meters and centimeters. Switching units converts the numbers you already typed.
- Enter each area as a rectangle, circle or triangle, or switch to Total area if you know the square footage.
- Enter the depth of this layer.
- Pick the material. The density fills in with a typical value; change it to your supplier's number if you have one.
- Order by the cubic yard or by the ton, whichever your supplier sells.
Gravel formula
Cubic feet = area in sq ft × (depth in inches ÷ 12) × (1 + extra % ÷ 100) Cubic yards = cubic feet ÷ 27 Short tons = cubic yards × density (tons per cubic yard) Metric tonnes = short tons × 0.9072 Cubic meters = cubic yards × 0.7646 Bags = cubic feet ÷ 0.5, rounded up
Worked example: a 30 × 3 ft path at 3 inches
- 30 × 3 = 90 square feet
- 90 × (3 ÷ 12) = 22.5 cubic feet
- 22.5 ÷ 27 = 0.83 cubic yards, or 0.64 cubic meters
- Crushed stone at 1.4 tons per cubic yard: 0.83 × 1.4 = 1.17 short tons, or 1.06 metric tonnes
- Bags: 22.5 ÷ 0.5 = 45 bags of 0.5 cu ft
Gravel weight by material
These are typical approximate loose weights used as starting values, not figures from one authoritative source. Real weight changes with the stone, the size range and how wet it is, so ask your supplier for the number they load trucks by.
| Material | Tons per cubic yard | Tonnes per cubic meter |
|---|---|---|
| Crushed stone | 1.4 | 1.66 |
| Pea gravel | 1.4 | 1.66 |
| River rock | 1.35 | 1.60 |
| Crusher run or road base | 1.5 | 1.78 |
| Sand | 1.35 | 1.60 |
| Decomposed granite | 1.4 | 1.66 |
Gravel per 100 square feet
| Depth | Cubic yards | Tons at 1.4 t/yd³ | 0.5 cu ft bags |
|---|---|---|---|
| 2 in | 0.62 | 0.86 | 34 |
| 3 in | 0.93 | 1.30 | 50 |
| 4 in | 1.23 | 1.73 | 67 |
| 6 in | 1.85 | 2.59 | 100 |
Pea gravel
Pea gravel is small, rounded stone. Because the stones are round they do not lock together the way crushed stone does, which decides how deep to lay it and how to hold it in place. Pick Pea gravel as the material above to use it in the calculator.
How deep to lay pea gravel
- Paths and patios: 2 to 3 inches is common practice. Round stones roll underfoot, so a thicker loose layer is harder to walk on and to move a chair across. This is general practice, not a code requirement.
- Play areas: the CPSC Public Playground Safety Handbook lists 9 inches of compressed pea gravel as protecting to a 5 foot fall height. It also notes that loose fill compresses at least 25 percent over time, so start with about 12 inches to keep 9.
Edging
Pea gravel spreads into lawns and beds unless something holds it. Steel, stone or plastic edging along the sides keeps it in place, and the CPSC handbook calls for a way to contain loose fill around a playground.
Example: a 10 × 12 ft play area
10 × 12 = 120 square feet at 12 inches of initial fill is 120 cubic feet, or 4.44 cubic yards. At 1.4 tons per cubic yard that is 6.22 tons, or 240 bags of 0.5 cu ft.
Base layer for driveways and paths
Typical practice, not an engineering specification: driveways and firm paths are built in two layers. The bottom layer is crushed stone with fines, such as crusher run or road base, compacted in place. The top layer is the stone you see. Run this calculator once for each layer with its own depth, material and compaction allowance, then add the totals. How thick the base must be depends on the soil, drainage and traffic, so confirm it with a local supplier or contractor before you order.
Tips
- Ask whether your supplier sells by the ton or by the cubic yard, and order in the unit they quote.
- Wet stone weighs more than dry stone, so a ton of wet material is less gravel.
- Bulk delivery needs room for the truck to dump. Bags make sense for small patches and hard-to-reach spots.
- Bags are rounded up to whole bags, and the bag size here is 0.5 cu ft. If your bags are a different size, divide the cubic feet by the size on the bag.