How to use this calculator
- Choose the shape of the area: a rectangle, a circle such as a tree ring or round bed, or a right triangle for a corner bed.
- Enter the length and width in feet (or metres). For a circle, enter the diameter as the length.
- Enter the depth in inches (or millimetres): 2–3″ for mulch, 4–6″ for new topsoil, 4″ for a typical concrete slab.
- If you have several beds of the same size, set the number of identical areas instead of adding them up by hand.
- Keep 10% extra for settling and uneven ground, pick the material to see its weight, and enter your supplier's price and delivery fee.
How to convert to cubic yards
Multiply the area by the depth, with every measurement in feet, to get cubic feet. Depth is usually measured in inches, so divide it by 12 first. Then divide the cubic feet by 27, because one cubic yard is 3 ft × 3 ft × 3 ft = 27 cu ft. For a circle the area is π × diameter² ÷ 4; for a right triangle it is half of length × width.
Example: a 12 × 10 ft bed filled 4″ deep with topsoil is 12 × 10 × (4 ÷ 12) = 40 cu ft, or 1.48 cu yd. Adding 10% for settling gives 44 cu ft, or 1.63 cu yd. Suppliers sell in quarter-yard steps, so the calculator rounds up to 1.75 cu yd. At $40 per yard plus a $75 delivery fee, that is $70 of soil and $145 in total. Topsoil weighs roughly 2,100 lb per cubic yard, so the load comes to about 1.7 US tons.
In metric the idea is the same: metres × metres × (millimetres ÷ 1,000) gives cubic metres. A 4 × 3 m bed at 100 mm is 1.2 m³, or 1.32 m³ with 10% extra, which rounds up to 1.4 m³. The table under the calculator shows how much area one cubic yard or cubic metre covers at common depths.
Pro tips
- Measure depth after you have dug out or leveled the area. A guess of "about 4 inches" over a large bed can easily be off by a third of a yard.
- Loose soil and mulch settle by 10–20% once they are watered and walked on, so don't skimp on the extra allowance for new beds.
- Check the payload before you collect a load yourself. A cubic yard of topsoil weighs about a ton, which is more than many half-ton pickups and small trailers should carry.
- For odd shapes, split the area into rectangles, circles and triangles, calculate each one and add the volumes together.
- Bagged soil and mulch come in 1, 1.5, 2 and 3 cu ft bags. It takes 13.5 bags of 2 cu ft to make one cubic yard, so bulk delivery usually wins above about one yard.
Frequently asked questions
How do I convert square feet to cubic yards?
Multiply the square footage by the depth in feet, then divide by 27. For example, 100 sq ft at 3″ deep is 100 × 0.25 = 25 cu ft, and 25 ÷ 27 = 0.93 cu yd.
How many square feet does a cubic yard cover?
One cubic yard covers 324 sq ft at 1″ deep, 162 sq ft at 2″, 108 sq ft at 3″, 81 sq ft at 4″ and 54 sq ft at 6″. In metric, one cubic metre covers 20 m² at 50 mm and 10 m² at 100 mm.
How many cubic feet are in a cubic yard?
There are 27 cubic feet in a cubic yard (3 × 3 × 3 ft). A cubic yard is also about 0.76 cubic metres, and one cubic metre is about 1.31 cubic yards.
How many cubic yards do I need for a 10 × 10 area?
At 3″ deep, a 10 × 10 ft area needs 25 cu ft, or 0.93 cu yd, so order 1 cu yd. At 4″ it is 1.23 cu yd, and at 6″ it is 1.85 cu yd before any allowance for settling.
How much does a cubic yard of dirt weigh?
Dry topsoil weighs about 2,000–2,200 lb per cubic yard and fill dirt about 2,300 lb, but wet soil can be much heavier. Bark mulch is far lighter at around 600 lb, while sand and gravel come in at about 2,700 lb and wet concrete at about 4,000 lb.
How do I calculate cubic yards for a circle?
Work out the area with π × diameter² ÷ 4, multiply by the depth in feet and divide by 27. A round bed 10 ft across with 3″ of mulch is 78.5 sq ft × 0.25 ft = 19.6 cu ft, or 0.73 cu yd.
These results are estimates for planning and budgeting. Actual quantities depend on site conditions, products and workmanship. Check structural and code requirements with a licensed professional before you build.