Raised bed soil calculator

Enter your bed size and fill depth to see how much soil to buy in cubic feet, cubic yards, liters or bags — and how much of each ingredient for an equal-thirds mix.

Results appear here.

How to use it

Measure the inside length and width of the bed (or the diameter for a round bed).
Enter how deep you will fill it.
Pick a bag size to see how many bags to buy, or choose "bulk" for cubic yards.

The formula

Rectangle: cubic feet = length (ft) × width (ft) × depth (in) ÷ 12 Circle: cubic feet = π × (diameter ÷ 2)² × depth (in) ÷ 12 Cubic yards = cubic feet ÷ 27 Liters = cubic feet × 28.3168 Bags = cubic feet ÷ bag size, rounded up Example: 4 × 8 ft bed filled 12 in deep = 32 cu ft = 1.19 cu yd = 22 bags of 1.5 cu ft

For filling a square-foot-style box, UF/IFAS Gardening Solutions suggests either blended compost alone or equal parts coarse vermiculite, peat moss and blended compost — that second option is the "equal parts" mix above. Bagged products are labeled by volume (cubic feet or quarts), so check the bag before you buy.

Gear for this job

Disclosure: some links on this site may be affiliate links; if you buy through them we may earn a commission at no extra cost to you. Learn more.

Raised garden bed kit — [affiliate link placeholder]
Bagged raised-bed soil mix — [affiliate link placeholder]
Compost — [affiliate link placeholder]
Coarse vermiculite — [affiliate link placeholder]
Soil test kit — [affiliate link placeholder]

Frequently asked questions

How much soil do I need for a 4×8 raised bed?

At 12 inches deep, 4 × 8 × 1 = 32 cubic feet, which is about 1.19 cubic yards or 22 bags of 1.5 cubic feet. At 6 inches deep it is half that: 16 cubic feet.

How many cubic feet are in a cubic yard?

27 (3 ft × 3 ft × 3 ft). Bulk soil is usually sold by the cubic yard; bags are sold by the cubic foot or quart.

Should I add extra for settling?

Many gardeners buy a little more than the exact volume because loose soil settles. There is no single standard figure, so the extra allowance field defaults to 0% and you can set your own.

What should I fill a raised bed with?

UF/IFAS suggests blended compost alone, or equal parts coarse vermiculite, peat moss and blended compost for square-foot gardening boxes. A soil test is the best guide for long-term beds.

Sources

Last reviewed 2026-10-22. Found an error? Tell us.