Topsoil & Raised Garden Bed Soil Calculator
Raised beds take a surprising amount of soil. A single 4x8 bed 12 in deep holds 32 cu ft, more than a pickup bed of bags. Enter your beds to get the total, with extra for settling.
Soil for common raised beds (10% settling)
| Bed | Cu ft | Cu yd | 1.5 cu ft bags | 2 cu ft bags |
|---|---|---|---|---|
| 4 × 4 ft, 12 in | 17.6 | 0.65 | 12 | 9 |
| 4 × 8 ft, 10 in | 29.3 | 1.09 | 20 | 15 |
| 4 × 8 ft, 12 in | 35.2 | 1.3 | 24 | 18 |
| 3 × 6 ft, 12 in | 19.8 | 0.73 | 14 | 10 |
| 4 × 12 ft, 12 in | 52.8 | 1.96 | 36 | 27 |
| 2 × 8 ft, 18 in | 26.4 | 0.98 | 18 | 14 |
What to fill a raised bed with
A widely used, budget-friendly blend is about 60% screened topsoil, 30% compost and 10% aeration material (perlite, pine bark fines or coarse sand). Bagged "raised bed mix" is convenient but costs more per yard than bulk once you pass 1–2 yards. In deep beds (18 in+), you can fill the bottom third with logs and branches (hügelkultur style) to cut soil volume. Expect it to settle more.
Topsoil for lawns and grading
Use the same math: area × depth ÷ 12. Spreading 1 in over 1,000 sq ft takes 83 cu ft (3.1 yd³). Bulk topsoil weighs roughly 1–1.2 tons per yard, depending on moisture.
Frequently asked questions
How much soil do I need for a 4x8 raised bed?
At 12 in deep, 32 cu ft (1.19 yd³). With 10% for settling, 35 cu ft, about 18 bags of 2 cu ft or 24 of 1.5 cu ft.
How many bags of soil in a cubic yard?
27 × 1 cu ft bags, 18 × 1.5 cu ft bags, or 13.5 × 2 cu ft bags.
Should I use topsoil or garden soil in raised beds?
Topsoil alone compacts. Mix it with compost (about 60/30/10 with an aeration material), or buy a raised-bed mix.
Last reviewed October 2026 by Jim Frith. These are planning estimates; confirm quantities with your supplier and follow local codes.