Soil volume calculator: the formula
Soil volume is area × depth: square feet × inches ÷ 12 gives cubic feet, and ÷ 27 gives cubic yards.
cubic yards = square feet × depth (in) ÷ 324
The 10 × 12 ft bed above is 120 sq ft; at 6 inches that is 120 × 0.5 = 60 cu ft, or 60 ÷ 27 = 2.22 cubic yards. One cubic yard is exactly 27 cubic feet, or 0.765 cubic meters.[3] For a round planter use 3.1416 × radius², for a strip around a lawn use the border shape, and for several beds of the same size enter how many. If you already know the area, the square feet to cubic yards chart gives the answer per inch of depth.
Garden soil calculator: how deep?
Most vegetables need 12–18 inches of good soil; 8–12 inches is enough for many raised beds and shallow-rooted crops.
| Planting | Soil depth | Source |
|---|---|---|
| Raised beds in general | 8–12 in | [4] |
| Vegetable beds | 12–18 in | [4] |
| Leafy greens, beans, cucumbers (bed on a hard surface) | at least 8 in | [5] |
| Peppers, tomatoes, squash (bed on a hard surface) | 12–24 in | [5] |
| Organic layer spread on an unframed bed | 2–3 in | [6] |
Oregon State's rule of thumb for that last row: one cubic yard covers 162 sq ft at 2 inches, so 6–7 cubic yards cover 1,000 sq ft.[6] For framed beds, the raised bed soil calculator adds several beds at once and splits the fill into topsoil and compost; Maryland Extension aims for 25–50% organic matter by volume in raised-bed soil.[5]
Potting soil calculator for pots and containers
Nursery "gallon" pots are size classes, not exact gallons: a #1 pot holds 152–251 cubic inches, while a true US gallon is 231 cubic inches.[2][3]
| Container | Cubic inches | Liters | Cubic feet | Pots per 1 cu ft bag |
|---|---|---|---|---|
| #1 | 152–251 | 2.5–4.1 | 0.09–0.15 | 6.9–11.4 |
| #3 | 628–742 | 10.3–12.2 | 0.36–0.43 | 2.3–2.8 |
| #5 | 785–1,242 | 12.9–20.4 | 0.45–0.72 | 1.4–2.2 |
| #7 | 1,337–1,790 | 21.9–29.3 | 0.77–1.04 | 1–1.3 |
| #10 | 2,080–2,646 | 34.1–43.4 | 1.2–1.53 | 0.7–0.8 |
| #15 | 2,768–3,696 | 45.4–60.6 | 1.6–2.14 | 0.5–0.6 |
The last column assumes the pot is filled to the rim; real fills stop an inch or so lower, so the same bag fills a few more pots. A pot sold as a "quart" or "four-inch" holds 57.75 cubic inches (one US liquid quart), and a pot labeled "#5T" or "#5 True" holds a true 5 gallons (5 × 231 = 1,155 cu in).[2] For a pot that is not on the list, measure it and use the circle shape above with its inside diameter and soil depth. Garden and potting soils are commonly sold in 0.75, 1, 1.5 and 2 cu ft bags.[7]
How much does soil weigh?
Dry topsoil weighs about 0.95–1.1 US tons per cubic yard, and wet topsoil about 1.4–1.6 tons.[1]
Moisture is the biggest variable: the same yard of soil can weigh half as much again after rain. Pick dry or wet in the calculator to see the weight range, and see how much a yard of dirt weighs for clay and fill. Filling a hole or low spot rather than a bed? The dirt calculator adds a compaction allowance.
Which soil calculator?Use this page for any soil volume. The topsoil calculator covers new lawns and top-dressing, and the compost calculator works out compost by the inch.
Common soil ordering mistakes
- Using the frame height instead of the soil depth: fill usually stops an inch or two below the top.
- Treating a trade-gallon pot as a true gallon: a #5 pot can hold anywhere from 785 to 1,242 cubic inches.[2]
- Ordering by weight without knowing the moisture: wet soil weighs far more per yard.[1]
Frequently asked questions
How do I calculate how much soil I need?
Multiply length × width in feet by the depth in inches, then divide by 324 for cubic yards (or by 12 for cubic feet).
How much soil is in a 1 gallon pot?
How many bags of soil make a cubic yard?
27 one-cubic-foot bags, 18 bags of 1.5 cu ft or 13.5 bags of 2 cu ft.
How deep should garden soil be?
About 12–18 inches for vegetables, 8–12 inches for many raised beds.[4]
Sources
- FM 5-434 Earthmoving Operations, Tables 1-1 and 1-2 (material weights, swell and conversion factors)
- American Standard for Nursery Stock (ANSI Z60.2-2025), section 1.1.3 and Table 1: container classes
- NIST Handbook 44, Appendix C: General Tables of Units of Measurement
- A Raised Bed Garden (E-560)
- Soil to Fill Raised Beds
- Raised Bed Gardening (FS 270)
- Miracle-Gro Garden Soil All Purpose (product label)