Fill Dirt Calculator

Fill dirt, topsoil and the one document behind every figure here

Fill dirt is bought for volume: subsoil, screened or not, that brings a low spot up to grade and gets compacted in lifts. Topsoil is bought for what grows in it. The exhibit this sheet cites does not use either trade name — its rows read Earth, loam and Topsoil, and the loam row is a highway fill material. It is the closest published figure to the subsoil a yard sells as fill dirt, not a match for it, and this page says so every time it prints one of its numbers.

The difference between the rows is a weight, not a volume: a loose cubic yard of damp loam is 2,360 pounds against 1,620 for topsoil. The same 300 square foot pad, 5.56 cubic yards either way, weighs 13,111 lb as damp loam and 9,000 lb as topsoil — 6.56 short tons against 4.5. Buy by the ton and that gap is the invoice.

One document supplies every density and every factor on this sheet: FHWA Federal Lands Highway’s Project Development and Design Manual, Earthwork Design, Exhibit 5.1 A. It offers its values The values shown in Exhibit 5.1 A may be used for estimating purposes prior to obtaining the project specific information from the Geotechnical Unit. Its own footnotes put ±5 % on the densities and 3. Based on average in-situ densities. A negative number represents a shrinkage. Factors subject to ±33% variation. Those tolerances travel with every number below. Read the exhibit.

Measuring the space: a rectangle, a circle, a triangle, and ground that slopes

Area times depth, then two divisions. The default pad is 20 by 15 feet at 6 inches: 300 × 6 ÷ 12 = 150 cubic feet, and 150 ÷ 27 = 5.56 cubic yards. A circle is measured across its diameter, πD² ÷ 4; a triangle by any side and the height square to it, base × height ÷ 2.

Ground that falls away is where hand arithmetic goes wrong. Tick depth changes across the area, measure at both ends, and the sheet averages them: 4 inches at the high end and 12 at the low end is a mean of 8 inches, so the same pad becomes 7.41 cubic yards instead of 5.56. That is exact rather than approximate: a surface sloping in one plane is a prism, and a prism’s volume is its base area times its mean height. A bowl or a ridge is not, so split it and add the areas.

The section drawing redraws itself from your own numbers, with two depth dimensions and a sloped top line when the depths differ. Of the six pages we could read, none redraws anything from what the visitor typed.

Three states of the same dirt: in place, loose, compacted

A cubic yard of ground is not a cubic yard of truck bed and not a cubic yard of finished fill. The exhibit states the spread plainly: 1 cuyd [1 m3] of earth in the cut may use 1.25 cuyd [1.25 m3] of space in the transporting vehicle, and finally occupy only 0.65 to 0.85 cuyd [0.65 to 0.85 m3] in the embankment. That is why one sheet has to carry three columns.

Both factors are divisions you can check, and both are rounded to two decimals here and used exactly as rounded, so the note on the takeoff prints the arithmetic the sheet actually ran. The exhibit also publishes its own swell and shrinkage percentages, which is a second route to the same factor, and the two routes do not always agree. Cross-check: the exhibit's own 43% swell over -4% shrinkage gives 1.49, the same factor. Cross-check: the exhibit's own 0% swell over -20% shrinkage gives 1.25, against 1.2 from the densities - the two cells of the same row disagree by about 4%, inside the exhibit's own ±33%. Cross-check: the exhibit's own 56% swell over -26% shrinkage gives 2.11, against 2.02 from the densities - the two cells of the same row disagree by about 4%, inside the exhibit's own ±33%. Both gaps sit inside the ±33 % the exhibit puts on its own factors.

Why this sheet compacts nothing until you tick the box

The one thing this sheet insists on. Nothing is converted: dirt sold by the yard is measured loose, the way it sits when it is spread.

Tick compacted to a specification and the pad goes from 5.56 to 8.28 cubic yards and from 13,111 to 19,536 pounds — half a load more, on a factor of 1.49. On the topsoil row the same tick multiplies by 2.02, which doubles the order. A sheet that applies that quietly is not being careful; it is selling dirt.

The compacted column of that exhibit is a highway embankment built and compacted to a federal specification. It is the only open, cited compacted figure the project has; it is not a promise about a trench, a garden bed or a crawl space, and the exhibit itself only offers it "for estimating purposes prior to obtaining the project specific information from the Geotechnical Unit".

If you have your own number, type it in the allowance field and it wins: the same pad with 15 % typed orders 6.39 cubic yards, and the takeoff calls it your figure rather than a published one. No percentage is suggested anywhere on this sheet. Of the six pages we could read, two apply a compaction or waste allowance to every result by default, one of them with no way to switch it off, and one recommends ordering extra in the body text; none of the six says where its percentage came from.

Digging instead of filling: swell, haul and what it would rebuild

Switch the mode to digging and the geometry stays, the factor reverses. The same footprint a foot deep in dry loam is 11.11 cubic yards in place; loose in a truck it is 11.11 × 1.46 = 16.22 cubic yards, because 3,030 ÷ 2,070 = 1.46. The weight on the ticket is the in-place weight, 11.11 × 3,030 = 33,667 pounds, and the loads are counted on the loose volume, which is the space you are actually paying to move. The last line answers the question an estimator really has: that loose pile would build 9.54 cubic yards of compacted fill somewhere else, 16.22 ÷ 1.7.

The wet loam row is the interesting one: the exhibit prints 0 % swell for it, so the sheet moves 11.11 in-place cubic yards as 11.11 loose cubic yards and says so rather than inventing a spread. Of the six pages we could read, not one models both directions: the two that handle compaction only shrink a delivered volume.

Weight, tonnage, loads — and the density you should overwrite

Weight is volume times a density, nothing more: 5.56 × 2,360 = 13,111 pounds, and 13,111 ÷ 2,000 = 6.56 short tons. In metric the sheet runs on the same row read as 1,400 kg/m³, so the arithmetic it shows is the arithmetic it did. Type a capacity and it divides: 8.28 cubic yards at 12 per load is 1 load rounded up. No payload is claimed here, because a tandem, a triaxle and a tag trailer are not the same truck.

The density field exists because a published average is not your supplier’s pile. Penn State’s Center for Dirt and Gravel Road Studies says it of its own calculator: the factors are averages from across PA, based on observations by Center field staff and actual conversion factors will vary by region and specific suppliers, so it invites a custom figure — its calculator is here, and the per-material numbers behind its dropdown are rendered in JavaScript, so we did not read them. Whatever your yard tells you a cubic yard weighs, type it: yours wins and the sheet labels it as yours. "Other" claims no density at all. Without one the sheet computes volumes and stops: no weight and no tonnage, because there would be nothing behind them. Ask the supplier what a cubic yard of the product weighs and type it in.

The gravel sheet weighs loam at 2,100 lb. Both figures are right. That sheet works from the Caterpillar earthwork tables, which carry a single Earth, Loam row, shown there in the dry and loose column; this one reads the exhibit’s three moisture rows and opens on damp, 2,360 lb the loose cubic yard. Against the exhibit’s own dry row, 2,070, Caterpillar’s 2,100 is 30 lb away. So choose by the job rather than by the number: aggregate delivered by the yard is weighed on the gravel calculator, fill placed and compacted is weighed here, and the row you pick above is what moves the tonnage.

What to ask before you order

• What does a cubic yard of this weigh? Write the answer in the density field.
• Is the yardage on the quote loose in the truck, or in place after compaction?
• Is it screened subsoil, unscreened site spoil, or topsoil — and is there any organic content?
• How many cubic yards does the truck that will show up actually carry?
• Is the price per yard delivered, or does haul bill separately?
• If the fill has to be compacted and tested, what compaction is specified and who tests it?

Area      A  =  L x W          rectangle
             =  pi x D^2 / 4    circle
             =  b x h / 2       triangle
Depth     d  =  (d1 + d2) / 2  when it varies
Space     V  =  A x d / 12     (sq ft, in -> cu ft)
Yards     Y  =  V / 27
Order     Yo =  Y                        default
             =  Y x embankment / loose    if compacted
             =  Y x (1 + a / 100)         if you type a
Haul      Yh =  Y x in-situ / loose       dig mode
Weight    Wt =  Yo x D   (lb per cu yd)
Tons      T  =  Wt / 2000
Loads     N  =  ceil( Yo / capacity )

Frequently asked

How do you calculate fill dirt needed?

Area times depth, then divide. The 300 sq ft pad above at 6 in is 150 cubic feet, 5.56 cubic yards after dividing by 27, and 13,111 lb at 2,360 lb per loose cubic yard. Order the yards you measured: dirt is sold loose, which is how it sits when you spread it.

How much does one ton of fill dirt cover?

2,000 lb divided by 2,360 lb per loose cubic yard is 0.85 cubic yards, or 22.9 cubic feet. Spread 6 in deep that covers 46 sq ft; at 3 in, twice that. Damp loam row, FHWA Exhibit 5.1 A, ±5 %.

How much will a 40 lb bag of topsoil cover?

On the exhibit's topsoil row, 1,620 lb of loose topsoil per cubic yard, a 40 lb bag is 0.67 cubic feet — 40.5 bags to a cubic yard, and about 8 sq ft an inch deep. Bagged soil is a blend sold by weight, so read the volume printed on your own bag before you multiply.

What does 1 ton of fill dirt look like?

About 0.85 cubic yards of damp loam: a heap roughly 2.8 ft on a side, or that 46 sq ft patch half a foot deep.

Is fill dirt cheaper than topsoil?

No price ships on this sheet, and the comparison is not one number anyway: the exhibit's loose rows are 2,360 lb per cubic yard for damp loam against 1,620 for topsoil, so a ton of topsoil is 1.23 cubic yards where a ton of loam is 0.85. Priced by the ton the volumes differ; priced by the yard the weights do. Ask two local yards for both, delivered.

How much is 20 yards of fill dirt?

In volume, 20 cubic yards is 540 cubic feet: 3,240 sq ft 2 in deep, 1,080 sq ft 6 in deep, 540 sq ft a foot deep. At the damp loam row it weighs 23.6 short tons. What it costs is a local quote this sheet does not invent.

Limits of this sheet

C-102 turns a plan area and one or two depths into a volume, a weight, a tonnage and, with a capacity, a number of loads, in both directions, and exports the takeoff to CSV — which none of the six pages does. It does not specify lifts or compaction testing, check bearing, or balance cut against fill across a site. The densities are published estimating figures for highway soil rows, not a measurement of your yard’s pile.

Sheet C-102 prepared by TakeoffMetric Editorial; no author, credential or field measurement is claimed.