Topsoil Calculator

How It Works

The calculator multiplies your area by your depth in feet to get cubic feet, then divides by 27 to get cubic yards. For bags, it divides cubic feet by the bag size and rounds up, since you cannot buy part of a bag.

A cubic yard is 27 cubic feet, per NIST Handbook 44. Bag sizes vary by brand, so check the label. Scotts sells its Premium Topsoil in 0.75 cubic foot bags, and Ace sells its All Purpose Top Soil in a 1 cubic foot size. Bag counts use the volume on the bag, not a product’s directions. Some bagged topsoil is meant to be mixed in, not laid as a full layer: for new lawns, the directions for Scotts Premium Topsoil say to spread 1 to 2 inches and mix it into the top 1 to 2 inches of native soil. Read the directions before you plan a deep layer from bags.

See Methods and Sources

Worked Example

Here is the math for a new lawn area that is 20 feet long, 10 feet wide, and 4 inches deep, using 0.75 cubic foot bags.

1. 20 ft x 10 ft = 200 sq ft
2. 200 sq ft x 4 in / 12 = 66.67 cu ft
3. 66.67 cu ft / 27 = 2.47 cu yd
4. 66.67 cu ft / 0.75 cu ft = 88.9 bags, rounded up to 89 bags

How Deep Should Topsoil Be?

The right depth depends on the job, and extension guides differ by region. Use these as a starting point, then check the advice for your area.

Topdressing alone will not fix a poor soil. University of Missouri Extension says adding a few inches of topsoil does not generally improve the texture or performance of heavy clay and poorly drained soils, unless it is done in combination with core aerification.

Topsoil in Raised Beds

Raised beds usually call for a mix, so topsoil may be only part of the volume. This calculator gives the whole volume of the bed, so multiply the result by the share of topsoil in your mix.

Iowa State University Extension suggests about 70 percent topsoil and 30 percent compost. For a 4 by 8 foot bed filled 12 inches deep, that is 32 cubic feet in all, or 1.19 cubic yards, of which about 22.4 cubic feet, or 0.83 cubic yards, is topsoil. University of Maryland Extension gives a mix of compost and purchased topsoil at a 1:2 or 1:1 ratio for beds over compacted clay, after loosening the subsoil.

Beds on a hard surface, such as a driveway, are different. Maryland Extension says to fill them with compost and a soilless mix, at least 8 inches deep for leafy greens, beans, and cucumbers, and 12 to 24 inches deep for pepper, tomato, and squash. It says topsoil can be added, up to 20 percent by volume, in beds at least 16 inches deep.

Cubic Yards of Topsoil by Area and Depth

Use this table for bulk orders. A 1,000 square foot lawn at 4 inches deep takes 12.35 cubic yards.

Bags of Topsoil by Area and Depth

These counts use 0.75 cubic foot bags, rounded up for each size.

Settling After You Spread

The result is the space to fill. Loose soil settles, so you may need to top it up later. The Kentucky guide says a newly graded lawn should be allowed to settle before planting, and that two or three good rains of at least a quarter inch, or irrigations, will help it settle. Fill or drain any low spots before you plant, and ask your supplier how much to order for your finished depth.

Check Topsoil Before You Buy

Quality varies, so look before you pay. University of Maryland Extension notes that topsoil sales are not regulated in Maryland, and suggests asking the seller for soil test results and where the soil came from. It says good topsoil should be dark and crumbly with an earthy smell, and that bags of “organic soil” typically do not contain topsoil. Missouri Extension adds that dark color and crumbly texture do not guarantee the soil has all the necessary nutrients, and recommends testing before you prepare soil for planting. The Kentucky guide is more cautious: if the topsoil on your lot is shallow, it says buying more is usually not the best idea, because good topsoil is hard to find, and you can end up with heavy clay or rocky soil that carries weed seed.

If you plan to grow food in a raised bed, Maryland Extension says to have the lab test the soil for lead. For raised beds, Iowa State says to make sure topsoil brought in from elsewhere is free of contaminants like lead and pesticides.

Frequently Asked Questions

These cover the questions that come up most often.