How it works
The calculator multiplies the area by the depth of the layer, adds any extra you enter, and divides by the bag size or multiplies by the density if you give them.
Area = Length × Width
Volume = Area × Depth × (1 + Extra ÷ 100)
Bags = ⌈ Volume ÷ Bag size ⌉
Weight = Volume × Weight per volume
⌈ ⌉ means rounding up to the next whole bag. The volume and weight are not rounded.
In US units this is the same as the University of California Agriculture and Natural Resources rule: square feet × depth in inches ÷ 324 = cubic yards. Units are converted internally, so an area in feet, a depth in inches and a bag size in cubic feet or liters all work together. The weight is only as good as the density figure: use the one from your supplier.
Worked example
Inputs
- Measure by
- Length × width
- Area length
- 20 ft
- Area width
- 10 ft
- Soil depth
- 4 in
- Extra
- 0 %
Result
- Topsoil volume
- 2.47 cu yd (66.67 cu ft)
Common mistakes
- Entering depth in feet instead of inches. Four inches is a third of a foot; a wrong unit multiplies the order by twelve.
- Guessing the weight. Topsoil from different suppliers, and the same soil wet or dry, can weigh very different amounts per cubic yard – ask for the figure.
- Assuming all bags are the same size. Bag volume varies by product; read the label.
- Comparing a bag price with a bulk price per cubic yard without converting. One cubic yard is 27 cubic feet.
Assumptions and limits
- The area is a rectangle, or you have entered its total area, and the depth is the same everywhere.
- The volume is area × depth plus any extra you enter. Settling and compaction are covered only by that extra.
- Weight is volume × the density you enter. No density is assumed – without one, only the volume is shown.
- Bags are rounded up to whole bags. The bulk volume and weight are not rounded.
Frequently asked questions
How do I work out cubic yards of topsoil by hand?
Multiply the area in square feet by the depth in inches and divide by 324. University of California Agriculture and Natural Resources gives this rule for mulch, and it works for any loose material spread in a layer; 324 is 27 cu ft per cu yd × 12 in per ft.
How many bags of topsoil are in a cubic yard?
Divide 27 cubic feet by the bag size. With 0.75 cu ft bags, such as Scotts Premium Topsoil, that is 27 ÷ 0.75 = 36 bags.
How much does a cubic yard of topsoil weigh?
It depends on the soil and its moisture, so this calculator doesn’t assume a figure. Ask your supplier for the weight per cubic yard of the product you are buying and enter it under Weight per volume.
How much extra should I order for settling?
Loose soil settles after it is spread and watered, but how much depends on the soil and how it is placed. Ask your supplier, and enter the allowance under Extra.
Sources
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
- Mulch calculation (area × depth in inches ÷ 324 = cubic yards) — University of California Agriculture and Natural Resources. Cubic yards of mulch = square feet × depth in inches ÷ 324.
- Scotts Nature Scapes Mulch 2 cu ft; Scotts Premium Topsoil — ScottsMiracle-Gro. Example bag sizes: mulch 2 cu ft (https://scottsmiraclegro.com/en-us/8840244.html), topsoil 0.75 cu ft.
Method reviewed November 2, 2026