Topsoil Calculator: Screened Loam for Lawns and Finish Grade
Enter your project dimensions
Order the compost blend for a lawn and you have paid for organic matter the mower will take off over two seasons. Lawns want screened loam, which is what this topsoil calculator sizes, and which is what the till around here has to be run through a screen to produce at all.
A 1,200 square foot lawn, worked all the way through
Hypothetical side yard, going down to seed, 4 inches of loam over a loosened subgrade.
- 1,200 sq ft
- 1,200 x 4, divided by 12 = 400 cu ft
- 400 / 27 = 14.81 cu yd
- 14.81 x 1.10 = 16.30 tons
- With the 5% box ticked: 15.56 cu yd, 17.11 tons
Now the same lawn as a half-inch topdressing: 50 cubic feet, 1.85 yards, 2.04 tons. Same area, an eighth of the order. Depth is doing all the work here, which is why it is the first thing to settle rather than the last.
| Job | Depth |
|---|---|
| Topdressing established grass | 1/4 to 1/2 inch |
| Over seed on a thin lawn | 1/2 to 1 inch |
| New seed or sod | 4 to 6 inches |
| New flower bed | 6 inches |
| Raised vegetable box | 12 inches, and use the blend instead |
Build any low subgrade up with fill first. Loam is for the top few inches where roots live, not for correcting a grade.
What the tool wants when the lawn is not a rectangle
Shape first. Rectangle for most of it, circle for a round island bed, multiple areas for up to five separate pieces added into one total. Front, side and the strip behind the shed come back as one figure and one delivery.
Length, width and diameter go in as feet. Depth goes in as inches, from 0.25 up to 24, which is why a quarter-inch topdressing is enterable at all.
Choose the material before reading the tons, because the weight is what changes.
The 5% box adds for compaction and spillage. On loam it earns its place: the low corners take more than you measured, and some of every load stays where the pile stood.
Results come back as cubic yards, tons and cubic feet, and Email my quote puts them in writing.
A yard of loam is 27 cubic feet; a ton of it is nine-tenths of that
Loam is sold here by volume and delivered by weight, so both numbers matter.
Screened loam runs about 2,200 lb per cubic yard, which is 1.10 tons, and that is the weight of the material as sold. Turn it round and a ton is about 0.91 of a yard. After a week of rain that same yard weighs more, which changes the shovel and not the coverage.
Cubic yards = area sq ft x depth in, divided by 12, divided by 27. Tons = cubic yards x 1.10.
Coverage per cubic yard, if you would rather work from area:
| Depth | One yard covers |
|---|---|
| 1/2 inch topdressing | 648 sq ft |
| 2 inches | 162 sq ft |
| 4 inches | 81 sq ft |
| 6 inches | 54 sq ft |
Ordering half a yard long, and where it goes
Round up. A lawn short of loam at the far end is a lawn with a visible seam in it for a year.
The surplus has somewhere to be. Low corners always take more than the tape said. Edges settle. Anywhere a machine turned during the work will want topping.
Timing matters more than the margin does. Have the load come the week you intend to spread it, and keep it off the grass it is standing on. A pile left through spring rain weighs about a third more per shovel and smears under the rake instead of breaking up.
Rough the subgrade up an inch before anything goes on top of it. Four inches of loose loam over a tight, smooth surface holds water like a pan. Set the finished grade falling away from the house, roughly 6 inches over the first 10 feet. Then settle it lightly rather than stamping it: a footprint about half an inch deep is right.
Loam, blend or fill under the seed
Three materials, and only one of them is this page.
Screened loam, sold as Top Soil. The natural surface layer, screened to take out the rock, roots and clumps that glacial till leaves in it. Lawns, finish grading, bed prep. About 2,200 lb a yard.
Garden soil, loam blended with compost, at about 2,000 lb a yard. Vegetable boxes and planting beds, sized on the garden soil calculator.
Fill dirt, subsoil at about 2,400 lb a yard. Structure, grade changes and holes, sized on the fill dirt calculator. Nothing grows in it, which is the point of it.
Checking a load before it is spread
Screened loam should look dark, fall apart loose in the hand, and smell earthy rather than sour.
Squeeze a moist handful. It should form a ball that breaks apart when poked. Smooth out into a ribbon and it is heavy with clay. Refuse to hold together at all and it is mostly sand.
Gray material or a sour smell points to a wet, airless pile. Visible white roots bring their own weeds with them. Take a photograph of anything odd before it goes down, while it is still one heap rather than a lawn.
With the yardage settled, open the product page, set a quantity and a date, and delivery is arranged at checkout by ZIP code. The truck wants firm ground and clear room to tip, which the delivery page sets out, and the other calculators cover the stone and the seed bed underneath.
Common questions
Why does the same 4 inches weigh so much less in loam than in the stone I ordered last year?
Weight per yard. Screened loam is about 2,200 lb; crushed stone is nearer 2,800 and crushed gravel 3,000. Identical volume, a third more on the truck. It is also why loam is talked about in yards and stone in tons.
Is the 5% enough on a new lawn?
For handling, yes. It does not cover the low ground you have not found yet. On a new seeding, tick the box and round the yardage up as well; on a topdressing the whole order is small enough that rounding up is the only allowance you need.
The lawn falls away toward the field. Does the slope change the area?
Slightly, and not enough to matter on ordinary ground. Pace it along the surface rather than taking it off a plan. What does matter is that a slope sheds water, so the downhill end will want a touch more depth than the top to finish level.
The lawn wraps round the house on three sides. Do I run it three times?
No. Use multiple areas, enter each side as its own rectangle, and take the single total. Up to five pieces. Keep the corners out of two rectangles at once, which is the usual way an order comes back high.
Do I measure up to the bed edging or past it?
Up to it. The beds are a separate depth and often a separate material. Measure the grass you are actually covering, then run the beds as their own entry at 6 inches if they are going in at the same time.
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Lawn math done? Soil's on us to deliver.
Screened topsoil by the cubic yard, free delivery across New Hampshire.
