Soil Calculator
Add your raised beds, rectangular, round or triangular garden beds and the soil depth to see exactly how many cubic feet, cubic yards, liters and bags of soil you need, plus the weight and whether bulk or bagged soil is cheaper. It runs entirely in your browser.
Garden beds
How to use the Soil Calculator
- Choose the bed shape: raised bed, rectangle, round or triangle.
- Enter the dimensions and the soil depth, each with its own unit (for example feet and inches).
- Add more beds with + Add bed, or set How many for identical beds.
- Set prices for bulk soil, delivery and bags to compare the cost, and add a settling allowance if you like.
- Press Calculate soil and copy the summary for your shopping list.
Soil volume formulas
Every calculation is area × depth. Work in feet to get cubic feet, then divide by 27 for cubic yards or multiply by 28.317 for liters.
| Bed shape | Area | Example (depth 10 in) |
|---|---|---|
| Raised bed / rectangle | length × width | 6 ft × 3 ft = 18 ft² → 15 ft³ |
| Round bed | π × (diameter ÷ 2)² | 5 ft circle = 19.63 ft² → 16.36 ft³ |
| Triangle bed | base × height ÷ 2 | 6 ft × 4 ft = 12 ft² → 10 ft³ |
Soil needed for common raised bed sizes
| Bed size | Depth | Cubic feet | Cubic yards | 1.5 cu ft bags |
|---|---|---|---|---|
| 2 × 4 ft | 12 in | 8 | 0.30 | 6 |
| 3 × 6 ft | 12 in | 18 | 0.67 | 12 |
| 4 × 4 ft | 12 in | 16 | 0.59 | 11 |
| 4 × 8 ft | 6 in | 16 | 0.59 | 11 |
| 4 × 8 ft | 12 in | 32 | 1.19 | 22 |
| 4 × 12 ft | 18 in | 72 | 2.67 | 48 |
Tips for filling garden beds
- Depth: 6–8 in for flowers and shallow-rooted greens, 10–12 in for most vegetables, 12–18 in for root crops and perennials. Top-dressing a lawn needs only ¼–½ in.
- Mix: a common raised bed recipe is about 60% topsoil and 40% compost by volume. Potting mix is light and pricey, so it is usually reserved for containers.
- Deep beds: to save soil in beds deeper than 18 in, fill the bottom with logs, branches or leaves (hügelkultur style) and calculate soil only for the top 12 in.
- Weight: a cubic yard of bulk topsoil weighs about a ton, more when wet, so check your truck or trailer payload before hauling it yourself.
Need mulch on top? Use the Mulch Calculator. For gravel paths or other materials, see the Cubic Yard Calculator.
Frequently asked questions
How much soil do I need for a 4×8 raised bed?
A 4 ft × 8 ft bed filled 12 inches deep needs 32 cubic feet of soil, which is 1.19 cubic yards or about 906 liters. That is 22 bags of 1.5 cu ft, 32 bags of 1 cu ft or 43 bags of 0.75 cu ft. At 6 inches deep you need half as much: 16 cu ft.
How do I calculate soil volume?
Multiply the bed area by the depth, using the same unit. For a rectangle that is length × width × depth in feet, which gives cubic feet; divide by 27 for cubic yards. Convert inches to feet by dividing by 12, so 8 inches is 0.667 ft.
How many bags of soil make a cubic yard?
A cubic yard is 27 cubic feet, so it takes 36 bags of 0.75 cu ft, 27 bags of 1 cu ft, 18 bags of 1.5 cu ft or 14 bags of 2 cu ft (13.5 rounded up). In liters a cubic yard is about 765 L, or 20 bags of 40 L.
Is it cheaper to buy soil in bulk or in bags?
For small jobs bags are often cheaper because bulk yards usually have a minimum order and a delivery fee. Beyond roughly 1–2 cubic yards bulk soil is normally much cheaper per cubic foot. Enter your local prices to compare.
How deep should soil be in a raised bed?
Most vegetables grow well in 8–12 inches of good soil; root crops like carrots and potatoes prefer 12 inches or more. Lawns need about 4–6 inches of topsoil and flower beds 6–8 inches.
Why should I add extra soil?
Fresh soil and compost settle by 10–20% after watering, and beds are rarely perfectly level. Adding 10% extra avoids a second trip to the store.