# How much soil do I need?

Computes the volume of soil or topsoil to fill rectangular or round garden beds to a depth, with an extra share for settling, in cubic yards, cubic feet, cubic metres and litres, and the number of bags.

- Page: https://www.acalculator.org/construction/soil-calculator
- JSON spec: https://www.acalculator.org/construction/soil-calculator.json
- Version: 96e1c48ef4f7

## Default answer

Example with the default inputs (Bed shape Rectangle, Length 10 ft, Width 4 ft, Depth 6 in, Number of beds 1, Extra for settling 10%, Bag size 1.5 ft³): Soil needed: 0.81 yd³ (22 ft³); bags to buy: 15.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| shape | Bed shape | Whether the bed is a rectangle or a circle. |
| l | Length | The length of the bed. |
| w | Width | The width of the bed. |
| d | Diameter | The diameter of a round bed. |
| depth | Depth | How deep to fill the bed with soil. |
| n | Number of beds | How many beds of this size to fill. |
| extra | Extra for settling | Soil to add on top of the bed volume, in percent, because loose soil settles and some is spilled. |
| bag | Bag size | The volume of soil in one bag, as printed on the bag. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| cubicYards | Cubic yards | The soil to buy, in cubic yards (27 cubic feet each). |
| cubicFeet | Cubic feet | The soil to buy, in cubic feet. |
| cubicMeters | Cubic metres | The soil to buy, in cubic metres. |
| liters | Litres | The soil to buy, in litres. |
| bags | Bags | How many bags of the given size hold that much soil: the volume ÷ the bag size, rounded up. |

## Method

Volume = length × width × depth (or π × diameter² ÷ 4 × depth) × beds × (1 + extra ÷ 100); bags = volume ÷ bag size, rounded up.

## Assumptions

- The bed is filled level to the depth you type, with straight sides.
- Extra for settling is 10% by default: loose soil settles after watering, and some is spilled. Set it to 0 for the bed volume alone.
- Bags are counted by the volume printed on the bag; soil is not compressed or loosened further.

## Worked examples

1. shape = rect, l = 3.048, w = 1.2192, depth = 0.1524, n = 1, extra = 10%, bag = 0.042475 gives cubicFeet = 22, cubicYards = 0.814815, cubicMeters = 0.622971, bags = 15. Source: NIST Handbook 44, Appendix C (1 yd³ = 27 ft³, 1 ft = 0.3048 m).
2. shape = rect, l = 3.048, w = 0.9144, depth = 0.1524, n = 1, extra = 0%, bag = 0.042475 gives cubicFeet = 15, bags = 10. Source: NIST Handbook 44, Appendix C.
3. shape = rect, l = 3, w = 1, depth = 0.3, n = 2, extra = 0%, bag = 0.04 gives cubicMeters = 1.8, liters = 1,800, cubicYards = 2.354311, bags = 45. Source: NIST Handbook 44, Appendix C (1 L = 0.001 m³, 1 yd = 0.9144 m).
4. shape = circle, d = 1.8288, depth = 0.3048, n = 1, extra = 0%, bag = 0.056634 gives cubicFeet = 28.274334, bags = 15.

## FAQ

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

Multiply the length by the width by the depth, all in the same unit. A bed 10 ft long and 4 ft wide filled 6 in (0.5 ft) deep needs 10 × 4 × 0.5 = 20 cubic feet. Divide by 27 for cubic yards: 0.74 yd³. Add about 10% for settling: 22 ft³, or 0.81 yd³.

### How many bags of soil do I need for a raised bed?

Divide the soil volume by the volume on one bag and round up. The 22 ft³ above fills 22 ÷ 1.5 = 14.67 bags of 1.5 cu ft, so buy 15 bags. With 2 cu ft bags it is 11 bags.

### How many cubic feet are in a cubic yard?

A cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet, which is about 0.765 cubic metres or 765 litres. Bulk soil is sold by the cubic yard; bagged soil by the cubic foot, quart or litre.

### How deep should soil be in a raised bed?

It depends on the plants. Many vegetables grow well in 6 to 12 in (15 to 30 cm) of soil; root crops and tomatoes do better with 12 in or more. Type the depth you plan to fill; the calculator does not pick one for you.

### Why add extra soil for settling?

Loose soil from a bag or a truck settles as it is watered and packed down, and some is spilled. The calculator adds 10% by default. Set the extra to 0% to get the volume of the bed alone.

### How do I calculate soil for a round bed?

Use the area of a circle: π × diameter² ÷ 4, then multiply by the depth. A round bed 6 ft across and 1 ft deep holds π × 36 ÷ 4 × 1 = 28.27 ft³ of soil.

## Sources

- NIST Handbook 44 (2024), Appendix C, General Tables of Units of Measurement: 1 yd³ = 27 ft³; 1 ft³ = 1,728 in³; 1 US gallon = 231 in³; 1 L = 0.001 m³; 1 ft = 0.3048 m. https://www.nist.gov/pml/owm/nist-handbook-44-current-edition
- OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area (volume of a rectangular solid and of a cylinder). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area