How to calculate topsoil
Multiply the area in square feet by the depth in inches and divide by 12 for cubic feet; divide by 27 for cubic yards, the unit bulk soil is sold in. Then add an allowance for settling: loose soil slumps after the first good soaking, and Roseville Rock Supply suggests ordering 5–10% extra.
Worked example — 1,000 sq ft of new lawn at 4 in: 1,000 × 4 ÷ 12 = 333 cu ft ÷ 27 = 12.35 cu yd. With 10% for settling, order 13.6 cu yd — about 14.9 tons of screened topsoil at 2,000–2,200 lb a yard.
Raised beds
A raised bed is a box: inside length × inside width × soil depth. A 4×8 ft bed 12 in deep holds 32 cu ft; with 10% for settling that is 35.2 cu ft — 24 bags of 1.5 cu ft or 36 bags of 1 cu ft. Measure inside the boards: lumber is smaller than its name, so a frame of two 2×6s stands 11 in, not 12. Popular sizes: 4×8×12, 4×8×18, 4×4×12, 3×6×18.
Bags per cubic yard
| Bag size | Bags per cubic yard | Bags for a 4×8×12 in bed (+10%) |
|---|---|---|
| 0.75 cu ft | 36 | 47 |
| 1 cu ft | 27 | 36 |
| 1.5 cu ft | 18 | 24 |
| 2 cu ft | 13.5 | 18 |
Topsoil, compost, blend or fill?
| Material | Weight per cu yd | Bulk price | Use it for |
|---|---|---|---|
| Screened topsoil | 2,200 lb | $32.95/yd³ (GA) to $51.95/yd³ (CA) screened | For new lawns, regrading and filling low spots. Roseville recommends 4–6 in under new lawn. |
| Compost | ≈ 1,000 lb | $32.05–$65.95/yd³ (NE Ohio, GA) | To amend beds or top-dress. MSU Extension: 2–3 in as a mulch layer. |
| Soil–compost blend (50/50) | ≈ 1,600 lb | $48–$74.95/yd³ (Mulch Pros 50/50 blend to Roseville garden blends) | Ready-to-plant mix for raised beds and new gardens. |
| Fill dirt (unscreened) | ≈ 2,400 lb | $25.95–$28.95/yd³ (GA, CA) | Subsoil for filling holes and raising grade. Cap it with topsoil where anything will grow. |
Only the topsoil weight comes from a published yard table (Roseville: 2,000–2,200 lb per yard); compost, blend and fill weights are estimates and swing widely with moisture. Weight changes your truck and pickup plans, not the volume you need.
Bags or bulk?
A 1 cu ft bag of topsoil at $2.85 works out to $76.95 per cubic yard, against $32.95–$51.95 for screened topsoil in bulk. With a $75 delivery fee and a $42.45 bulk price, bulk is cheaper from about 2.2 cubic yards — roughly 176 sq ft at 4 in. Raised beds sit near that line: one or two beds are usually a bag job, a whole garden of them is a bulk job. Compost is pricier either way ($9.95 per 1.5 cu ft bag, $32.05–$65.95 per yard bulk).
Measuring odd shapes and low spots
For a curved bed, measure its length, then its width every few feet along it, and multiply the length by the average width. Split L-shaped areas into rectangles and add them up (the calculator takes up to three). For low spots, push a stake in at the deepest point and a few points toward the edges, and use the average depth — ordering for the deepest reading over the whole area buys far too much.
Getting a load delivered
A cubic yard of screened topsoil weighs about a ton, so even a small raised-bed order outweighs a half-ton pickup's nominal payload. Yards send up to about 5 tons on a single-axle truck and up to 18 tons on a tandem; Roseville Rock Supply asks for 10 ft of width, 14 ft of height clearance and firm, level ground where the truck dumps. Lay a tarp on the driveway first, and have the pile dropped as close to the beds as the truck can safely reach.
Common mistakes
- Forgetting settling — a bed filled flush to the top sits noticeably lower after a few soakings.
- Using the nominal board height for raised beds instead of measuring inside.
- Filling beds with fill dirt. It is unscreened subsoil meant for raising grade, not for growing.
- Ordering by weight from one yard and by volume from another without converting — ask how they sell it.
- Planning to haul it in a pickup: a yard of topsoil weighs about a ton, twice a half-ton's nominal payload.
Finishing the beds? The mulch calculator covers the top layer, and the gravel calculator handles paths between beds. Leveling a yard with sand instead? Use the sand calculator.