Topsoil Calculator: The Last Four Inches, by the Yard

The order this page most often has to correct is a large one: twenty yards of topsoil bought to cure a corner of the yard that ponds every March. Topsoil will not hold a grade. It is the last four to six inches, the part roots live in, and spread two feet deep over soaked lake-plain clay it gives you a soft patch that settles for years. The topsoil calculator sizes that finish layer. Whatever has to be raised underneath it is a separate order.

Depth by job, per thousand square feet of lawn

Depth moves the order far more than area does, so settle it before measuring anything. These are the figures per 1,000 square feet, at the site's published 1.1 tons per cubic yard:

Twenty-four times as much soil sits at the bottom of that table as at the top, on the same thousand square feet.

Where the last four inches start, and what goes underneath

This site keeps three bulk soils and they are not interchangeable. Screened topsoil is natural surface soil with the stones, roots and clods taken out of it, and it is what goes under seed and sod. Fill dirt is compactable subsoil for raising ground, sized on the fill dirt tool. Garden soil is topsoil blended with compost for beds and planters, sized on the bed soil tool.

For the ponding corner at the top of this page, the honest sequence is fill dirt brought to within four to six inches of finished level, compacted in layers, and then topsoil over the top. Run each layer through its own tool at its own depth and keep the two yardages apart on the order, even if they arrive together.

Turning an odd-shaped back lawn into something the topsoil calculator accepts

The form takes a rectangle, a circle by its diameter, or up to five separate areas added together in one run. Lawns are rarely any of those, so break the yard into the rectangles it is actually made of: the strip along the drive, the open middle, the piece behind the garage.

Measurements go in feet and depth goes in inches, from 0.25 to 24, which covers a quarter-inch dressing and a full four-inch rebuild alike. Choose the material so the tonnage matches, decide on the optional checkbox that adds 5 percent for compaction and spillage, and read the answer as cubic yards, tons and cubic feet together. The box starts ticked, and nothing is added if you untick it. There is an option to have the estimate emailed over.

Subtract the beds, the patio and the shed footprint. On a small lot those can be a fifth of what a tape measure round the boundary would suggest.

A 2,150-square-foot lawn seeded once the frost is out

Take a back lawn of 2,150 square feet going in at four inches over a loosened subgrade:

• 2,150 x 4 / 12 = 716.67 cubic feet
• 716.67 / 27 = 26.54 cubic yards
• 26.54 x 1.1 = 29.2 tons
• with the allowance ticked: 27.9 cubic yards, 30.7 tons

Order 28 yards. Loosen the ground an inch before spreading, because topsoil laid on sealed clay perches water instead of letting it through, and set the fall away from the house at roughly six inches over the first ten feet. Firm it lightly rather than stamping it: a footprint in finished topsoil should press in about half an inch.

Timing is the Michigan part. Ground has to be thawed and dry enough to work, and soil delivered into a wet week smears rather than rakes. Book the delivery for the week you intend to spread, not the week you decide to.

Topdressing thin grass at three-eighths of an inch

Topdressing is the other half of this page and almost a different trade. Across 5,500 square feet at three-eighths of an inch you need 171.9 cubic feet, 6.4 cubic yards and about 7 tons. Spread it thin, drag it in with the back of a rake until the grass tips stand clear, and leave the rest until next season.

The temptation after a hard winter is to go thicker. Resist it. More than about half an inch at a time buries the grass you are trying to help, and anything over an inch is a grade change, which means killing or lifting the turf first rather than smothering it and living with the lumps for a year.

Ordered by the yard, delivered at about 2,200 pounds each

Square feet times depth in inches, divided by 12, gives cubic feet. Divide by 27 for cubic yards, which is the unit topsoil is ordered in. Multiply by 1.1 for tons, which is what tells you the size of the load rather than the size of the order. Screened topsoil is about 2,200 lb a cubic yard dry, lighter than fill dirt at roughly 2,400 and heavier than blended garden soil at about 2,000, which is the organic content showing up on the scales.

Rain adds weight and not volume. The 2,200 lb figure is the material as sold; a yard that has sat through a wet week weighs more than that, so it shovels heavier and rakes worse, but the coverage has not changed. Read backwards, a cubic yard covers 648 square feet at a half-inch dressing, 162 at two inches, 81 at four and 54 at six.

The 5 percent box, the low corners and the last wheelbarrow

Five percent covers spillage and small measuring errors. What it does not cover is the low corner nobody averaged, and lawns are full of those. Take depth readings in three or four places across a yard before settling on one number, and where the ground dips, treat the dip as its own area rather than adding an inch everywhere.

Rounding up is cheap insurance on a lawn, because the last wheelbarrow always has somewhere to go: a thin edge along the drive, the strip by the fence, the ruts the delivery left. Coming up short means a seeded lawn with a bald patch you will be looking at all summer.

With the yardage set, open the screened topsoil page, choose a quantity and a date, and finish at checkout, where delivery is arranged by ZIP code. Leave a firm, clear spot for the truck and a tarp under the pile if it is landing on a drive.

Common questions

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