Soil for a 4x12 Raised Bed 18 Inches Deep
A raised bed 4 by 12 feet and 18 inches tall holds 72.0 cubic feet. How much soil for a 4x12 raised bed 18 inches deep in bags: 36 two-cubic-foot bags. In bulk: about 2.67 cubic yards.
Volume and tonnage calculator →The math
- Volume: 4 × 12 × (18 ÷ 12) = 72.0 cu ft.
- Cubic yards: 72.0 ÷ 27 = 2.67 yd³.
- Bags: 72.0 ÷ 2 = 36 bags (2 cu ft), or ÷ 1.5 = 48 bags (1.5 cu ft).
The topsoil calculator handles any bed size.
Related: Soil for a 4x8 Raised Bed 18 Inches Deep
Soil for a 4x12 bed at other depths
| Depth | Cubic feet | Cubic yards | 2 cu ft bags |
|---|---|---|---|
| 6 in | 24.0 | 0.89 | 12 |
| 8 in | 32.0 | 1.19 | 16 |
| 10 in | 40.0 | 1.48 | 20 |
| 12 in | 48.0 | 1.78 | 24 |
| 18 in | 72.0 | 2.67 | 36 |
| 24 in | 96.0 | 3.56 | 48 |
When bulk soil pays off
Bulk soil is usually cheaper per cubic yard than bags once you pass roughly 1 yard. At 2.67 yards, bulk delivery is likely the better deal. Fill several beds at once to make a delivery worthwhile.
Related: Soil for a 4x4 Raised Bed 18 Inches Deep
A good raised bed mix
A common home mix is roughly 60 percent topsoil and 40 percent compost, or equal parts topsoil, compost and a drainage material. Avoid filling with plain clay fill dirt, which packs hard.
Settling
Expect the bed to sink a few inches as the soil settles and organic matter breaks down. Mound it a little at first and water it in before planting. In very deep beds, the bottom few inches can be coarse material, since most vegetable roots work the top 12 inches.
Checking quality
Good bulk soil is dark, crumbly and free of trash, large rocks and weed roots. Ask whether it is screened and whether compost is blended in. If possible, look at the pile before ordering or ask for a sample.
Timing the job
Plan deliveries for a dry stretch so the pile and the ground are workable. Early spring mulching suppresses weeds before they sprout, while fall soil work gives beds time to settle before planting.
Questions people ask
How many bags of soil for a 4x12 raised bed?
About 36 bags of 2 cubic feet at 18 inches deep.
How many cubic feet in a 4x12x18 inch bed?
72.0 cubic feet.
How many yards of soil for a 4x12 raised bed?
About 2.67 cubic yards at 18 inches deep.
What soil mix is best for raised beds?
Topsoil blended with compost, roughly 60/40, is a common starting point.
Will raised bed soil settle?
Yes, often 10 to 20 percent in the first season.
Related guides
- How Much Does a Yard of Topsoil Cover?
- How Many Bags of Topsoil in a Yard? Size Chart
- Fill Dirt vs Topsoil: Differences, Uses and Tons to Order
- How Much Does a Yard of Dirt Weigh? Topsoil, Fill, Clay
- Soil for a 4x10 Raised Bed 12 Inches Deep
- Soil for a 4x12 Raised Bed 12 Inches Deep
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