Topsoil Calculator — Cubic Yards and Bags
Enter the area and how deep you need to fill. You get cubic yards for a bulk order and a bag count if the job is small.
About the Topsoil Calculator
Topsoil is the material people most reliably under-order, because depth is invisible until you start filling. A bed that looks like it needs a few bags usually needs a yard. This gives you the volume and the weight, so you can judge whether a delivery or a car boot full of bags is realistic.
How to use it
- Measure the area to fill in feet.
- Enter the depth — 6 inches for new beds, 2 to 3 for levelling a lawn.
- For raised beds, use the internal dimensions and the full internal height.
- Compare the bag count against the yardage before deciding how to buy.
The formula
Cubic yards = length × width × (depth ÷ 12) ÷ 27
Screened topsoil weighs roughly 1.1 tons per cubic yard when dry, more when wet. Bagged soil is normally 1 cubic foot, so one cubic yard is 27 bags.
Worked examples
| Area | Depth | Cubic feet | Cubic yards | 1 cu ft bags |
|---|---|---|---|---|
| 20 ft × 10 ft | 6" | 100 | 3.70 | 100 |
| 4 ft × 8 ft raised bed | 12" | 32 | 1.19 | 32 |
| 50 ft × 30 ft lawn | 2" | 250 | 9.26 | 250 |
| 3 ft × 3 ft | 6" | 4.5 | 0.17 | 5 |
The second row is the one that surprises people. A single 4 × 8 raised bed swallows over a cubic yard — 32 bags — which is most of a pickup load for one bed.
Common mistakes
- Buying bags for a bulk job. Past about one cubic yard, bags cost far more and mean 27 trips to the car. Bulk delivery is usually cheaper even with the fee.
- Confusing topsoil with garden soil. Topsoil is a base material. Raised beds want a compost blend; plain topsoil compacts and drains badly in a container.
- Forgetting settlement. Fresh soil settles 10 to 20% after watering. Fill slightly proud or plan to top up.
- Ordering unscreened soil for fine work. Unscreened is cheaper and full of rocks and roots. Fine for bulk fill, miserable for a seed bed.
Terms explained
- Screened topsoil
- Put through a mesh to remove stones and debris. Costs more, saves hours of picking.
- Cubic yard
- 27 cubic feet. Covers 108 sq ft at 3 inches, or 54 sq ft at 6.
- Triple mix
- Equal parts topsoil, compost and peat or manure. The usual choice for beds rather than plain topsoil.
- Fill dirt
- Subsoil with no organic content. For raising grade only — nothing grows well in it.
Common questions
- How many cubic yards of topsoil do I need?
- Multiply length by width by depth in feet, then divide by 27. A 20 × 10 area at 6 inches deep needs 3.7 yards.
- How many bags of topsoil in a cubic yard?
- Twenty-seven of the 1 cubic foot bags, or about 13 of the 2 cubic foot bags.
- How much does a yard of topsoil weigh?
- Roughly 2,200 lb dry, and noticeably more when wet. Most half-ton pickups handle one yard at a time.
- How deep should topsoil be for grass?
- Four to six inches of good soil for a healthy lawn. Two inches is enough for topdressing an existing one.
- What is the difference between topsoil and garden soil?
- Topsoil is a base material sold in bulk. Garden soil is amended with compost and nutrients, sold in bags, and better for planting directly.
- How much topsoil for a 4x8 raised bed?
- At 12 inches deep, 32 cubic feet — about 1.2 cubic yards or 32 of the 1 cubic foot bags.
- Should I till topsoil into existing soil?
- Yes, for lawns. A sharp layer boundary stops roots crossing. Mixing the top few inches gives a far better result.