Soil for a 3x3 Raised Bed 12 Inches Deep
A raised bed 3 by 3 feet and 12 inches tall holds 9.0 cubic feet. How much soil for a 3x3 raised bed 12 inches deep in bags: 5 two-cubic-foot bags. In bulk: about 0.33 cubic yards.
Volume and tonnage calculator →The math
- Volume: 3 × 3 × (12 ÷ 12) = 9.0 cu ft.
- Cubic yards: 9.0 ÷ 27 = 0.33 yd³.
- Bags: 9.0 ÷ 2 = 5 bags (2 cu ft), or ÷ 1.5 = 6 bags (1.5 cu ft).
The topsoil calculator handles any bed size.
Related: Soil for a 4x10 Raised Bed 12 Inches Deep
Soil for a 3x3 bed at other depths
| Depth | Cubic feet | Cubic yards | 2 cu ft bags |
|---|---|---|---|
| 6 in | 4.5 | 0.17 | 3 |
| 8 in | 6.0 | 0.22 | 3 |
| 10 in | 7.5 | 0.28 | 4 |
| 12 in | 9.0 | 0.33 | 5 |
| 18 in | 13.5 | 0.50 | 7 |
| 24 in | 18.0 | 0.67 | 9 |
Bags or bulk?
Bulk soil is usually cheaper per cubic yard than bags once you pass roughly 1 yard. At 0.33 yards, bags are simpler. Fill several beds at once to make a delivery worthwhile.
Related: Soil for a 5x10 Raised Bed 12 Inches Deep
What to fill it with
Many gardeners blend topsoil with compost, around 50 to 60 percent topsoil. The compost adds nutrients and keeps the mix loose. Bagged potting soil alone is light and can dry out fast in a deep bed.
Settling
New soil settles, often by 10 to 20 percent in the first season. Overfill slightly or plan to top up with compost next spring. Line the bottom with cardboard to smother grass instead of digging it out.
Timing the job
Spring and early fall are the easiest times to spread soil and mulch: the ground is workable and plants are ready to root. Avoid spreading right before heavy rain, which can wash fresh material off slopes and into drains.
Measuring accurately
Walk the area with a tape and sketch it. Break odd shapes into rectangles and circles. If you are topping up an existing bed or lawn, measure only the new depth, since adding a full depth on top of existing soil overbuys.
Questions people ask
How many bags of soil for a 3x3 raised bed?
About 5 bags of 2 cubic feet at 12 inches deep.
How many cubic feet in a 3x3x12 inch bed?
9.0 cubic feet.
How many yards of soil for a 3x3 raised bed?
About 0.33 cubic yards at 12 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 2x6 Raised Bed 10 Inches Deep
- Soil for a 2x8 Raised Bed 12 Inches Deep
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