Raised Garden Bed Soil Volume: Cubic Feet, Bags, and Bulk Cost
October 21, 2026
Filling raised garden beds is a major cost of getting started, so it is worth calculating exactly how much soil you need. The volume is length × width × depth. A 4 × 8 foot bed filled 12 inches deep needs 4 × 8 × 1 = 32 cubic feet, which is 1.19 cubic yards. If bagged soil comes in 1.5-cubic-foot bags, that is 21 to 22 bags. If you buy by the cubic yard in bulk, you need slightly over a yard, and you may want to add 10% for settling.
Soil settles by 10% to 20% in the first season as it compacts and organic matter breaks down, so fill generously and top up each year.
Skip the math and get your answer instantly:
Open the Mulch & Soil Calculator →Volume by Bed Size
Common raised-bed sizes and depths produce the volumes below. Depth is typically 8 to 12 inches for most vegetables, with 12 to 18 inches for deep-rooted crops like carrots and tomatoes, and a minimum of 6 inches for shallow-rooted greens.
| Bed size | Depth | Volume (cubic feet) | Cubic yards |
|---|---|---|---|
| 4 x 4 ft | 12 in | 16 | 0.59 |
| 4 x 8 ft | 12 in | 32 | 1.19 |
| 4 x 8 ft | 8 in | 21.3 | 0.79 |
| 3 x 10 ft | 12 in | 30 | 1.11 |
| 4 x 12 ft | 18 in | 72 | 2.67 |
Bags or Bulk?
Bagged soil typically costs about $5 to $9 per 1.5-cubic-foot bag, or $3.50 to $6 per cubic foot, which is around $95 to $160 per cubic yard. Bulk soil mixes are often $40 to $80 per cubic yard plus delivery, which makes bulk far cheaper for beds that need more than one cubic yard. For the 4 × 8 foot bed at 1.19 cubic yards, bulk at $60 per yard costs about $71 plus a delivery fee, versus 22 bags at $7, or $154.
Prices vary by region and quality. Ask bulk suppliers about their compost content and screening, and look at the material in person. Avoid soil that smells sour or contains large amounts of wood chips or debris.
A Good Soil Mix
A common recipe for raised beds, called Mel's Mix in the square-foot gardening method, is one third compost, one third peat moss or coconut coir, and one third vermiculite. Many gardeners prefer a mix of about 50% topsoil, 30% compost, and 20% aeration material such as perlite or coarse sand, or simply 60% topsoil and 40% compost. Using compost from several sources adds a range of nutrients. The mix should be loose and drain well but hold some moisture.
For the 32-cubic-foot bed, a 60/40 mix needs about 19 cubic feet of topsoil and 13 of compost, or 0.71 and 0.47 cubic yards.
Ways to Reduce Cost
Fill the bottom third of deep beds with logs, branches, leaves, and other coarse organic matter, a technique known as hugelkultur, which decomposes and holds moisture. Use cardboard on the ground to smother weeds. The top 8 to 12 inches should be good soil because that is where most roots grow. Making your own compost is cheap and reduces the amount you need to buy. Check local resources: many municipalities offer free or low-cost compost.
Maintaining Fertility
Top up each year with 1 to 2 inches of compost, which restores nutrients and replaces settled soil. Rotate crops to prevent disease buildup, and get a soil test every few years to check pH and nutrient levels.
Frequently Asked Questions
How much soil do I need for a 4x8 raised bed?
About 32 cubic feet (1.2 cubic yards) at 12 inches deep.
How deep should a raised bed be?
8 to 12 inches suits most vegetables, with 12 to 18 inches for deep-rooted crops.
Is bulk soil cheaper than bagged?
Usually much cheaper per cubic foot, once you need more than about a cubic yard.
How much will the soil settle?
Typically 10% to 20% in the first season.
What is a good raised bed soil mix?
A blend such as 60% topsoil and 40% compost, or a compost-peat-vermiculite mix.