# How much gravel do I need?

Computes the volume of gravel for a rectangular or round area at a depth, in cubic yards and cubic metres, its weight in tons at a bulk density, and the cost.

- Page: https://www.acalculator.org/construction/gravel-calculator
- JSON spec: https://www.acalculator.org/construction/gravel-calculator.json
- Version: de8d22270bb4

## Default answer

Example with the default inputs (Area shape Rectangle, Length 20 ft, Width 10 ft, Depth 4 in, Density 105 lb/ft³, Price per Ton (2,000 lb)): Covering the area 4 in deep takes 2.47 yd³ of gravel, about 3.5 ton.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| shape | Area shape | A rectangle, or a circle. |
| len | Length | The length of the area. |
| wid | Width | The width of the area. |
| dia | Diameter | The diameter of the round area. |
| dep | Depth | How thick the layer of gravel is. |
| density | Density | The bulk density of the gravel. Dry gravel is about 105 lb/ft³; wet gravel about 125 lb/ft³. |
| price | Price | The price per ton, tonne or cubic yard. Leave empty to skip the cost. |
| per | Price per | The unit the price is for. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| cubicYards | Gravel | The volume of gravel in cubic yards. |
| cubicFeet | Cubic feet | The volume of gravel in cubic feet. |
| cubicMeters | Cubic metres | The volume of gravel in cubic metres. |
| tons | Weight in tons | The volume × the density, in US short tons of 2,000 lb. |
| tonnes | Weight in tonnes | The volume × the density, in metric tonnes of 1,000 kg. |
| cost | Cost | The weight or volume in the price unit × the price. |

## Method

volume = area × depth; weight = volume × density; cubic yards = cubic feet ÷ 27; tons = pounds ÷ 2,000

## Assumptions

- Rectangle: length × width. Circle: π × diameter² ÷ 4.
- The default density is dry gravel, 105 lb/ft³ (1,680 kg/m³), from the Engineering ToolBox. Wet gravel is about 125 lb/ft³. Ask your supplier for the density of their stone.
- The volume is the loose volume of the layer. It adds nothing for compaction or waste.

## Worked examples

1. shape = rectangle, len = 6.096, wid = 3.048, dep = 0.1016, density = 1,681.938654, per = ton, price = $40.00 gives cubicFeet = 1.88779, tons = 3,175.14659, cost = $140.00. Source: hand calculation in content.mdx: 20 × 10 × 4/12 = 66.67 ft³ = 2.47 yd³; × 105 lb/ft³ = 7,000 lb = 3.5 tons; × $40 = $140.
2. shape = circle, dia = 3.6576, dep = 0.0762, density = 1,681.938654, per = yd3, price = $55.00 gives cubicFeet = 0.80064, cost = $57.60. Source: hand calculation in content.mdx: π × 12² ÷ 4 × 0.25 = 9π = 28.27 ft³ = 1.047 yd³; × $55 = $57.60.
3. shape = rectangle, len = 10, wid = 3, dep = 0.1, density = 1,680, per = t, price = $50.00 gives cubicMeters = 3, tonnes = 5,040, cost = $252.00. Source: hand calculation in content.mdx: 10 × 3 × 0.1 = 3 m³; × 1,680 kg/m³ = 5,040 kg = 5.04 t; × $50 = $252.

## FAQ

### How do I calculate how much gravel I need?

Multiply length × width × depth, all in feet, for cubic feet, and divide by 27 for cubic yards. A 20 ft × 10 ft area 4 in deep is 20 × 10 × 4/12 = 66.67 ft³, or 2.47 cubic yards.

### How many tons of gravel are in a cubic yard?

At the dry gravel density of 105 lb/ft³, a cubic yard (27 ft³) weighs 27 × 105 = 2,835 lb, or 1.42 tons. Wet gravel, at about 125 lb/ft³, weighs 3,375 lb, or 1.69 tons.

### How deep should gravel be?

It depends on the job and the stone size. Paths and decorative beds are often a few inches deep; driveways are built in layers of larger base stone topped with smaller stone. Follow your supplier’s or designer’s depth for your use.

### Why does the supplier’s tonnage differ from mine?

Gravel is sold by weight, and its density depends on the stone, its size and how wet it is. Ask the supplier for the density of the product and type it under Weight and cost.

### Should I order extra gravel?

The volume here is the exact loose volume. Gravel settles and compacts under traffic and some spreads past the edges, so many people round up to the next whole ton or yard.

### How do I work out a round area?

Choose Circle and enter the diameter. The area is π × diameter² ÷ 4, so a 12 ft circle is 113.1 ft².

## Sources

- Engineering ToolBox, Dirt and Mud - Densities: gravel, dry 105 lb/ft³ (1,680 kg/m³); gravel, wet 125 lb/ft³ (2,000 kg/m³). https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html
- NIST SP 811 (2008), Appendix B: 1 ft = 0.3048 m and 1 lb = 0.45359237 kg exactly; 1 short ton = 2,000 lb.