How Much Soil Do I Need for a Raised Bed? Chart by Bed Size

Updated October 8, 2026

Multiply the bed's length, width and depth in feet. A 4 × 8 ft bed 12 inches deep holds 32 cubic feet of soil, which is about 1.2 cubic yards, 22 bags of 1.5 cu ft or 16 bags of 2 cu ft. For any size, use the topsoil calculator.

Raised bed soil formula

cubic feet = length (ft) × width (ft) × depth (in) ÷ 12
cubic yards = cubic feet ÷ 27
bags = cubic feet ÷ bag size (cu ft)

Check the bag: soil is labeled in cubic feet (often 1, 1.5 or 2 cu ft) or in quarts. 1 cubic foot is about 25.7 dry quarts, so a 50 quart bag is about 1.9 cu ft.

Soil for common raised bed sizes

Bed	Cu ft	Cu yd	1 cu ft bags	1.5 cu ft bags	2 cu ft bags
2 × 4 ft, 10 in deep	6.7	0.25	7	5	4
3 × 6 ft, 12 in deep	18.0	0.67	18	12	9
4 × 4 ft, 10 in deep	13.3	0.49	14	9	7
4 × 4 ft, 12 in deep	16.0	0.59	16	11	8
4 × 8 ft, 10 in deep	26.7	0.99	27	18	14
4 × 8 ft, 12 in deep	32.0	1.19	32	22	16
4 × 8 ft, 18 in deep	48.0	1.78	48	32	24
4 × 12 ft, 12 in deep	48.0	1.78	48	32	24
2 × 8 ft, 24 in deep	32.0	1.19	32	22	16

Fill the bed to about an inch below the top. New soil also settles by 10 to 20% over the first season, so plan on topping it up next spring.

Bags or bulk?

Once you need more than about a cubic yard (two 4 × 8 beds at 10 inches), bulk soil from a landscape supplier is usually much cheaper than bags, even with a delivery fee. Ask for a raised bed or garden mix rather than plain topsoil.

What soil to put in a raised bed

A simple mix: about 60% topsoil, 30% compost and 10% coarse material like perlite or fine bark for drainage.
Don't use only bagged potting mix in big beds. It's expensive and drains too fast at that volume.
Deep beds (18 in or more): fill the bottom third with logs, branches or leaves to save soil. They break down slowly and feed the bed.
Mulch the top with an inch or two of straw or shredded bark to keep moisture in. The mulch calculator gives the amount.