Dirt Calculator for Fill, Grading and Backfill
Enter your project dimensions
A hollow in a Virginia lawn is rarely a hollow in the soil you can plant in. Under the grass sits clay, sand or old sediment that has settled, washed or been dug out, and the material that belongs back in it is screened subsoil rather than anything a seed would enjoy. That is the split this dirt calculator is built around: it sizes the structural layer that brings a grade back up, and the growing layer that goes over it is a separate order and a separate tool.
Why the deepest point is the wrong depth to type in
A low area is a dish, not a box. The deepest place in the middle is the number most people reach for, and it can put the order half again over what the ground will take. Probe the depth at the middle, at the edges and at two points between, then enter the average of those readings in the depth field. On a settled trench line running across a yard, take a reading every few feet along it instead.
Filling all the way up and leaving the lawn nothing to root into
Fill dirt is low in organic matter by design, which is why it stays put and why grass struggles on it. Stop the fill 4 to 6 inches below the finished level you want, then bring the last layer back up with screened topsoil. Two calculations, two materials, one delivery.
Reading a wet load as extra yardage
Rain adds weight, not volume. Dry fill runs about 2,400 lb a cubic yard, which is 1.2 tons, and a soaked yard of the same material can reach 3,000 lb. The order does not change; the wheelbarrow does. After a long wet spell on Piedmont clay, soaked fill smears rather than compacts, so the weather decides the date rather than the quantity.
Raising a 24 by 17 hollow in a Northern Virginia yard
A worked example, hypothetical rather than a customer job. A lawn hollow measures 24 ft by 17 ft, so 408 square feet. Probing gives 12 inches at the center and 6 at the edges, so the average depth below finished grade is 9 inches. The top 4 inches of that will be topsoil, leaving 5 inches of fill.
Five inches is 5/12 of a foot, so 408 x 5/12 gives 170 cubic feet. Divided by 27 that is 6.30 cubic yards, and at 1.2 tons a yard it comes to 7.56 tons. With the 10 per cent box ticked the figure reads 8.3. The topsoil course is 408 x 4/12, or 136 cubic feet, which is 5.04 cubic yards; screened topsoil is lighter at about 2,200 lb a yard, so that layer weighs about 5.5 tons. Size it on the topsoil calculator so the weight figure matches the material.
What the form is asking you for
Pick rectangle for a square-edged fill and enter length and width in feet. A round depression takes circle and a diameter in feet. Multiple areas takes up to five entries at once, which is how a yard with three separate low patches gets one total instead of three trips to the form.
Depth (inches) accepts 0.25 up to 24. That ceiling matters on fill work more than on any other calculation here, because a hole can be deeper than two feet. Split a deep void into two entries under multiple areas, the lower part and the upper part, and add what comes back.
The material select drives the weight conversion, and the tick box, on by default, adds 10 per cent for compaction and spillage unless you untick it. The results appear as cubic yards, tons and cubic feet, and Email my quote sends the set to you.
Yards to order by, tons to plan the day around
Cubic yards are the figure to think in on fill work, because that is what the hole holds and what the pile in the drive will look like. Fill is sold here by the cubic yard, so yards are also what the order is written in. Tons tell you what is landing on the drive and how long the spreading will take, and the two are linked by the material weight rather than by anything about your site. Cubic feet are handy on small backfill: a post hole or a settled trench end is easier to picture in feet than in fractions of a yard.
Fill dirt, topsoil or garden soil, and which tool sizes each
The three materials are ordered for three different jobs, and each has its own calculator so the tonnage is converted at the right weight.
- Fill dirt is screened subsoil for structure: grade changes, berms, backfill and holes. About 2,400 lb a cubic yard dry. Size it here.
- Top Soil is the screened growing layer, 4 to 6 inches over the fill for lawn and beds. About 2,200 lb a yard, and the topsoil calculator is the one to use.
- Garden Soil is a blend for raised beds and planting areas, lighter again at about 2,000 lb a yard. The soil calculator handles it.
If the layer will carry weight, it is fill. If something has to grow in it, it is not.
Three fill jobs and the numbers behind them
A utility trench 30 ft long and 2 ft wide, backfilled 15 inches deep, is 60 square feet at 1.25 ft: 75 cubic feet, 2.78 cubic yards, about 3.3 tons.
A screening berm 24 ft long and 5 ft wide, averaging 10 inches once its slopes are allowed for, is 120 square feet at 10/12 ft: 100 cubic feet, 3.7 cubic yards, about 4.4 tons.
Building a pad up before base stone goes down is the same sum, and it is the one to keep separate from the stone order. The fill goes in first, in layers of 6 to 8 inches with each one compacted or soaked and left to firm, and the 21A goes on top once the grade is where you want it, with sizing the stone layer done as its own calculation. On flat Coastal Plain lots where water already sits close to the surface, a raised pad is doing drainage work as much as leveling work, so the fill depth is worth getting right before the stone is ordered. Once the yardage is settled, set the quantity and a date on the product page; delivery is arranged at checkout from your ZIP code, and how delivery is arranged covers what the truck needs at the far end.
Common questions
How do I split one order between the fill underneath and the topsoil on top?
Run the fill depth here and the topsoil depth on its own calculator, then place both on the same delivery. For a 400 square foot area finished with 4 inches of topsoil, that top layer alone is about 4.9 cubic yards, and everything below it is the fill figure from this page.
The low ground is a long curved sweep rather than a square. How should I measure it?
Lay it out as two or three rectangles that between them cover the sweep, enter them under multiple areas, and take an average depth for each one separately. Curved edges tend to be the shallow parts, so a rectangle that slightly overshoots the edge usually balances against the depth you lose there.
Part of the yard was filled last year and has settled again. What do I enter?
Run a string line at the level you want and measure down to the sunken surface at several points, then enter that average as the depth. Settlement of this kind is usually 1 to 3 inches, well inside the depth field's range, and it is worth checking that nothing organic was buried in the first fill before you top it.
What happens if the load turns out to be short?
The area finishes low, and on a lawn that means the next heavy rain finds the dip again. Fill is the one material where a modest surplus is easy to place, since it disappears into a berm, a low corner or a spoil pile without waste.
How reliable is the figure the calculator returns?
The volume side is arithmetic and does not vary. What moves the real quantity is the ground: compaction takes a loose layer down by a tenth or more, and a soft or saturated subgrade takes some of the first layer into itself. Measure the depth in several places, and finish lawn work about half an inch high so settlement lands it flush.
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Screened fill dirt for grading and backfill, delivered across Virginia.
