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Raised Bed Soil Calculator
Work out how much soil you need to fill one or several raised garden beds. Enter the length, width and depth, pick a soil mix, and get the total in cubic yards and cubic feet, how much of each ingredient to buy, and how many bags that is.
Results are estimates. Soil, stone and mulch settle, weigh differently and vary by supplier. Confirm quantities and local requirements before ordering.
Soil needed for common raised bed sizes, 12 in deep
| Bed size | Cubic feet | Cubic yards |
|---|---|---|
| 2 × 8 ft | 16 | 0.59 |
| 3 × 6 ft | 18 | 0.67 |
| 4 × 4 ft | 16 | 0.59 |
| 4 × 8 ft | 32 | 1.19 |
| 4 × 12 ft | 48 | 1.78 |
How to calculate it
The volume of a raised bed is length × width × depth. Measure the inside of the bed in feet, with the depth being the height of the soil, not the board. Multiply the three, and divide by 27 to turn cubic feet into cubic yards.
Soil settles after the first watering, so order about 10% extra. For a blended mix, each ingredient is its share of the total. A 60% topsoil, 30% compost and 10% sand blend splits the total volume in those proportions.
Worked example
One 8 ft × 4 ft bed filled 12 inches deep with a 60/30/10 blend, with 10% extra:
| Bed volume (no extra) | 32 cu ft 1.19 cubic yards |
|---|---|
| Soil to order | 1.3 cubic yards includes 10% extra for settling |
| Topsoil | 0.78 cubic yards 60% of the mix |
| Compost | 0.39 cubic yards 30% of the mix |
| Coarse sand or perlite | 0.13 cubic yards 10% of the mix |
| 1 cu ft bags | 36 bags |
| 1.5 cu ft bags | 24 bags |
| 2 cu ft bags | 18 bags |
| Wheelbarrow loads | 9 loads about 4 cu ft per trip in a 6 cu ft wheelbarrow, part-filled |
| Cubic meters | 1 m³ |
Tips
- Fill to 1–2 inches below the rim so soil and water do not spill over when you water.
- Bulk soil delivered by the cubic yard is usually much cheaper per cubic foot than bags once you need more than about 1 cubic yard.
- Top the bed up with compost each year. The soil level drops as organic matter breaks down.
- Check the delivery minimum. Many suppliers deliver in whole or half yards.
Assumptions and sources
- Volume = length × width × depth × number of beds. Default extra 10% for settling.
- Mix splits: Garden bed blend: 60% topsoil, 30% compost, 10% coarse sand or perlite; Half and half: 50% topsoil, 50% compost; Equal thirds: compost, peat moss or coco coir, vermiculite; Ready-made raised bed mix only.
- Bags are counted at 1, 1.5 and 2 cu ft.
- 1 cubic yard = 27 cubic feet = 0.764555 cubic meters.
- 1 US ton = 2,000 lb = 907.185 kg.
- Quantities that are bought whole (bags, boards, pavers, pallets) are rounded up.
Densities and bag sizes are typical supplier and manufacturer figures, not guarantees. Unit conversions follow NIST exact definitions. Full details are on the methodology page. Last reviewed October 2026.
Frequently asked questions
How much soil do I need for a 4×8 raised bed?
A 4 × 8 ft bed filled 12 inches deep needs 32 cubic feet, which is 1.19 cubic yards. With 10% extra for settling, order about 1.3 cubic yards.
How many bags of soil is that?
32 cubic feet is 32 one-cubic-foot bags, 16 two-cubic-foot bags or about 22 bags at 1.5 cubic feet. Add the settling allowance on top.
What is a good soil mix for raised beds?
A common blend is about 60% topsoil, 30% compost and 10% coarse sand or perlite. Another is equal parts compost, peat moss or coco coir, and vermiculite. Pick whichever your supplier stocks and the calculator splits the amounts.
How deep should a raised bed be?
Most vegetables do well in 10 to 12 inches of soil. Greens and herbs manage with 6 to 8 inches. Deep-rooted crops such as carrots and tomatoes appreciate 12 inches or more.