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Soil to fill one or more raised garden beds: cubic feet, cubic yards, bags, and a compost / peat / vermiculite mix.
With these inputs:
| Result | Value |
|---|---|
| Soil for all beds | 64 ft³ (2.37 yd³) |
| In 1.5 cu ft bags | 43 bags |
| Per bed | 32 ft³ |
| Mix: compost / peat or coir / vermiculite | 21.3 ft³ of each |
| Bed | 8 × 4 ft, 12 in deep |
| Beds | 2 |
| Top-up allowance | 0% |
| Growing area | 64 sq ft |
The equal-thirds mix is Mel Bartholomew's Square Foot Gardening recipe, measured by volume. A bed that sits on open ground does not need the full depth of bought soil: loosen the ground underneath and fill the top 6 to 12 inches.
A raised bed holds more soil than it looks like: an 8 × 4 ft bed 12 inches deep takes 32 cubic feet, over a cubic yard. Enter the bed size, depth and how many you are filling for the total in cubic feet and yards, the bag count at the size you are buying, and the three-way Square Foot Gardening mix split into equal parts.
Multiply length × width × depth in feet. A 4 × 8 ft bed 12 inches deep is 32 cubic feet — 1.19 cubic yards, or 22 bags of 1.5 cu ft. At 6 inches deep it is half that: 16 cubic feet.
Divide the bed's cubic feet by the bag size and round up. Two 8 × 4 ft beds at 12 inches hold 64 cubic feet, which is 43 bags of 1.5 cu ft or 32 bags of 2 cu ft. Above about a cubic yard, bulk delivery is often worth pricing.
A popular recipe is Mel Bartholomew's Square Foot Gardening mix: one third compost, one third peat moss (or coconut coir), one third coarse vermiculite, by volume. For 64 cubic feet that is about 21.3 cubic feet of each.
Six inches suits lettuce and herbs, and 12 inches suits most vegetables. Deeper beds cost more to fill; if the bed sits on soil, loosen the ground beneath and let deep roots grow down into it.
27 — a cubic yard is 3 × 3 × 3 feet. So 64 cubic feet is 2.37 cubic yards.
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