Free tool for raised-bed gardeners
Raised bed soil calculator
Multiply length × width × depth, all in feet, to get cubic feet; divide by 27 for cubic yards. A 4 × 8 ft bed filled 12 inches deep needs 32 cubic feet, about 1.19 cubic yards or 906 liters: 22 bags of 1.5 cubic feet.
Last updated 2026-10-30.
- Soil needed
- cubic feet
- Cubic yards
- Liters
- Bags
Enter positive numbers for size, depth, beds and bag size.
Example scenarios
Three sets of example inputs worked through the same formulas as the calculator above. They are illustrations, not averages or statistics.
| Scenario | Bed (length × width × depth) | Cubic feet | Cubic yards | Liters | Bags of 1.5 cu ft |
|---|---|---|---|---|---|
| Low | 6 × 3 ft, 10 in deep | 15 | 0.56 | 425 | 10 |
| Typical | 8 × 4 ft, 12 in deep | 32 | 1.19 | 906 | 22 |
| High | 12 × 4 ft, 16 in deep | 64 | 2.37 | 1,812 | 43 |
Method: Cubic feet = length (ft) × width (ft) × depth (in) ÷ 12 × number of beds, plus any top-up allowance; cubic yards = cubic feet ÷ 27; liters = cubic feet × 28.317; bags = cubic feet ÷ bag size, rounded up. Figures checked against the same formulas on 2026-10-30.
How the calculator works
A raised bed is a box, so the soil it holds is its inside length times its inside width times the depth you fill it to. The calculator turns your depth from inches into feet (12 inches is 1 foot), multiplies the three numbers and then the number of beds. It shows the result in cubic feet, the unit most US bagged soil is sold in, in cubic yards, the unit bulk soil from a landscape yard is sold in, and in liters.
Bags are rounded up to whole bags, because a store will not sell you two thirds of a bag. If you add a top-up allowance, the calculator adds that percentage to the volume before it counts bags.
Measure the inside, not the outside
Boards have thickness. A bed built from 2 × 6 lumber on a 4 × 8 ft outside footprint has an inside that is a few inches shorter on each side, and that difference adds up over a long bed. Measure the inside length and width with a tape, and measure depth from the bottom of the bed to the level you plan to fill to, not to the top edge of the boards.
Worked examples
One bed, 4 × 8 ft, filled 12 inches deep: 4 × 8 × 1 = 32 cubic feet. 32 ÷ 27 = 1.19 cubic yards. 32 × 28.317 = 906 liters. With 1.5 cubic foot bags: 32 ÷ 1.5 = 21.3, so 22 bags.
Two of the same beds: 64 cubic feet, 2.37 cubic yards, 43 bags of 1.5 cubic feet.
A smaller bed, 3 × 6 ft, filled 10 inches deep: 3 × 6 × 10 ÷ 12 = 15 cubic feet, 0.56 cubic yards, 10 bags of 1.5 cubic feet.
Bags or bulk?
Bags are easy to carry and store, and you only buy what you use. Bulk soil is sold by the cubic yard and delivered in one load, often with a delivery fee and a minimum order. The calculator shows both numbers so you can price the two options side by side with your local stores. It does not know prices or what any store sells; check the bag size printed on the bag you plan to buy and enter that size.
What this tool does not do
It only does the arithmetic of volume. It does not recommend a soil mix, a depth or a brand. Soil also settles after watering, so many gardeners keep some extra soil for topping up later; the allowance field lets you plan for your own amount.
Questions
How many cubic feet are in a cubic yard?
27. A cubic yard is 3 ft × 3 ft × 3 ft.
How do I convert cubic feet to liters?
Multiply by 28.317. One cubic foot is 28.317 liters.
Does this page store what I type?
No. The math runs in your browser; nothing is sent or saved.
We are also planning a paid product: Raisedyear, a month-by-month raised-bed garden year. It is not available yet; its page shows the planned price, and reserving charges nothing. See the planned product