How to use this calculator
- Choose the material. This only changes the approximate weight; the volume is the same for any material.
- Enter the length and width of the area and the depth you want to spread.
- Add a small allowance for settling and uneven ground.
- Pick the bag size you plan to buy, or use the cubic yards / cubic meters figure to order in bulk.
The formula
Volume (ft³) = length (ft) × width (ft) × depth (in) ÷ 12 Cubic yards = volume (ft³) ÷ 27 Weight ≈ cubic yards × material densityCommon depths
| Use | Typical depth |
|---|---|
| Mulch on garden beds | 2–3 in (5–8 cm) |
| Decorative gravel | 2–3 in (5–8 cm) |
| Topsoil for new beds or lawns | 4–6 in (10–15 cm) |
Approximate densities used
| Material | Per cubic yard | Per cubic meter |
|---|---|---|
| Mulch | ≈ 0.3 tons (600 lb) | ≈ 350 kg |
| Topsoil | ≈ 1.1 tons | ≈ 1,300 kg |
| Gravel | ≈ 1.4 tons | ≈ 1,660 kg |
| Sand | ≈ 1.35 tons | ≈ 1,600 kg |
Tons here are US short tons (2,000 lb). Wet material can weigh noticeably more.
Worked example
A 10 × 10 ft flower bed covered with 3 inches of mulch:
- 10 × 10 × 3 ÷ 12 = 25 ft³, which is 25 ÷ 27 = 0.93 cubic yards.
- In 2 cu ft bags: 25 ÷ 2 = 12.5, so buy 13 bags (before any settling allowance).
Tips
- Keep mulch a few inches away from tree trunks and plant stems.
- For gravel paths and driveways, a compacted base layer under the top gravel makes the surface last longer.
- Bulk delivery is often cheaper than bags once you need more than a cubic yard or so. Compare local prices.
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft mulch. In practice you would buy 14 bags.
How much does a cubic yard of gravel weigh?
Roughly 1.4 tons (about 2,800 lb), depending on stone size and moisture. Ask your supplier for the exact figure if you are ordering by weight.
How deep should mulch be?
About 2–3 inches (5–8 cm) is a common depth for garden beds. Thicker layers can keep water and air from reaching the soil.
Does the material change the volume I need?
No. The volume depends only on the area and depth. The material only changes the approximate weight shown.