40lb Bag of Topsoil to Cubic Feet & Cubic Yards: Conversion Chart
Updated April 30, 2026 · 5 min read
Topsoil Bag-to-Volume Conversion Chart
Topsoil is sold by weight, not volume — so cubic feet per bag varies with moisture and soil density. These ranges cover typical bagged garden topsoil.
| Bag size (weight) | Cubic feet (range) | Cubic yards | Bags per cubic yard |
|---|---|---|---|
| 20 lb bag | 0.25 – 0.4 cu ft | ~0.011 cu yd | ~90 bags |
| 30 lb bag | 0.4 – 0.55 cu ft | ~0.017 cu yd | ~60 bags |
| 40 lb bag | 0.5 – 0.75 cu ft | ~0.022 cu yd | ~45 bags |
| 50 lb bag | 0.6 – 0.9 cu ft | ~0.028 cu yd | ~36 bags |
| 1 cu ft bag | 1.0 cu ft (exact) | ~0.037 cu yd | 27 bags |
| 2 cu ft bag | 2.0 cu ft (exact) | ~0.074 cu yd | 13.5 bags |
| 1 cu yd (bulk) | 27 cu ft (exact) | 1 cu yd | — |
How Many 40lb Bags for Common Projects?
| Project | Volume needed | 40lb bags |
|---|---|---|
| 4×8 raised bed (12" deep) | 32 cu ft (1.2 cu yd) | ~53 bags |
| 4×4 raised bed (12" deep) | 16 cu ft (0.6 cu yd) | ~27 bags |
| 3×6 raised bed (12" deep) | 18 cu ft (0.67 cu yd) | ~30 bags |
| Lawn topdressing (¼" over 1,000 sq ft) | ~21 cu ft (0.78 cu yd) | ~35 bags |
| Tree planting (typical 3' wide × 2' deep) | ~14 cu ft | ~24 bags |
| Filling a 4×4 sod patch (3" deep) | 4 cu ft | ~7 bags |
| Half cubic yard project | 13.5 cu ft | ~22 bags |
| Full cubic yard project | 27 cu ft | ~45 bags |
| 2 cubic yards | 54 cu ft | ~90 bags |
The Math Behind the Conversion
Topsoil density varies between 75 and 110 pounds per cubic foot. A reasonable average is 90 lbs per cubic foot for moist garden topsoil:
- 1 cubic foot ≈ 90 lbs
- 40 lbs ≈ 0.44 cubic feet (using 90 lbs/cu ft, dense)
- 40 lbs ≈ 0.6 cubic feet (using 67 lbs/cu ft, fluffier mix)
- 1 cubic yard = 27 cubic feet ≈ 1,800 to 2,400 lbs
Why the wide range? Bagged "topsoil" varies in composition. Pure mineral topsoil is denser. Topsoil mixed with peat moss, compost, or coir is fluffier. Wet bags weigh significantly more than dry bags for the same volume.
Manufacturers don't publish exact cubic foot specs because the volume changes with moisture. If you see a bag labeled "0.5 cu ft" or "0.75 cu ft", that's the manufacturer's stated volume — use that number when planning.
Bagged vs Bulk: When to Switch
For small projects, bags are convenient. For larger projects, bulk delivery saves a lot of money:
- Bagged topsoil: $3–6 per 40lb bag at home improvement stores. ~45 bags per cubic yard = $135–270 per cubic yard.
- Bulk topsoil: $30–60 per cubic yard delivered (delivery fees of $50–150 added). Break-even point is typically 30–35 bags or about 0.7 cubic yards.
Rule of thumb: If you need more than 30 forty-pound bags, call a landscape supplier. For under 20 bags, stick with bagged.
Frequently Asked Questions
How many cubic feet is a 40lb bag of topsoil?
A 40lb bag of topsoil contains approximately 0.5 to 0.75 cubic feet, depending on moisture content and soil density. Use 0.6 cubic feet as a planning average.
How many cubic yards is a 40lb bag of topsoil?
A 40lb bag is roughly 0.022 cubic yards (1/45 of a yard). It takes about 45 forty-pound bags to make one cubic yard.
How many 40lb bags equal a cubic yard of topsoil?
About 45 forty-pound bags. (27 cubic feet per yard ÷ 0.6 cu ft per bag ≈ 45.)
How much does a cubic yard of topsoil weigh?
Dry topsoil: about 1,800 lbs per cubic yard. Wet topsoil: up to 2,400 lbs per cubic yard.
What's the difference between topsoil and garden soil?
Topsoil is the natural top layer of soil, usually screened to remove rocks. Garden soil is topsoil amended with compost, peat moss, or fertilizer for specific plant types. Garden soil is typically lighter and more expensive.