Fill Dirt Calculator
This fill dirt calculator works out how much a hole, pad or low spot needs, with the compaction allowance built in, because loose dirt shrinks once it is rolled.
Fill Dirt Needed
Sloped or Uneven Ground
A low spot is rarely a rectangle of even depth. Averaging the depth across the area is the practical way to measure one.
Compaction Lifts
Fill is placed in layers and each layer is compacted before the next goes on. Dumping the whole depth at once leaves the bottom loose.
Fill Dirt Cost
How to use the Fill Dirt Calculator
Measure the area to be filled and the depth you want once it is finished and compacted. That is the compacted volume, the hole, not the pile.
Then leave the compaction allowance in. Loose dirt off a truck packs down hard under a roller, so the loose volume you have to buy is always a great deal larger than the hole you are filling, commonly thirty-five to fifty percent larger. Set it to zero only if the fill will never be compacted.
If the ground slopes or dips, use the Sloped panel and give the depth at each end rather than guessing an average.
Fill Dirt Cost prices the loose volume rather than the finished one, and splits delivery out by truck size. A 10-yard truck on a job needing 30 yards is three deliveries, and that often costs more than the dirt itself.
Fill Dirt formula
compacted volume = length × width × depth ÷ 27cubic yardsloose volume = compacted volume × (1 + compaction%), where the allowance iscompacted density ÷ loose density − 1tons = loose volume × density ÷ 2,000average depth = (shallow + deep) ÷ 2on ground that falls evenlylifts = ceiling(total depth ÷ compacted lift thickness)
| Material | lb per yd³ | tons per yd³ |
|---|---|---|
| Screened fill dirt | 2,200 | 1.10 |
| Bank run, unscreened | 2,500 | 1.25 |
| Sandy fill | 2,600 | 1.30 |
| Clay fill | 2,700 | 1.35 |
Weights are for material at ordinary moisture. Saturated dirt is heavier and behaves very differently under a roller.
The compaction allowance follows from those weights. Fill leaves the yard loose at around 2,200 lb/yd³ and ends up in the ground at roughly 3,000 to 3,240 lb/yd³, so every compacted yard needs about 1.4 loose yards delivered. That is where the forty percent comes from; it is not a waste allowance.
Worked example
A 40 × 30 ft pad raised 12 in and compacted:
- Compacted volume: 40 × 30 × 1 = 1,200 cu ft = 44.44 cu yd
- Plus 40% compaction: 62.22 cu yd loose to buy
- At 2,200 lb/yd³: 62.22 × 1.1 = 68.4 tons
- In 14 yd tandem loads: 5 loads
Ordering the 44.44 cu yd that the hole measures would leave the pad three and a half inches low once it was rolled, it would compact down to about 31.75 cu yd, or 8.6 in of the 12 you wanted.
What the result means
Fill dirt is not topsoil. Fill is subsoil chosen for stability, low organic content, so it does not rot away and settle later. Topsoil is chosen for growing things and is the wrong material to build on. A pad is built with fill and finished with a few inches of topsoil on top.
Compaction is the whole point. Dirt dumped and left alone will settle for years, and anything built on it settles with it. Fill placed in lifts and compacted reaches its final level immediately.
Buy loose, place compacted. The yard sells you loose material by volume off a truck. You measure the hole compacted. The gap between the two is roughly forty percent, loose fill weighs about 2,200 lb a yard and compacted fill about 3,100, and it is why fill orders come up short.
Clay holds water. It compacts well when the moisture is right and turns into a bathtub when it is not. Sandy fill drains but needs more compaction effort to hold.
Common mistakes
- Ordering the compacted volume. The commonest fill mistake, and it is short by a fifth every time.
- Filling with topsoil. The organic content breaks down and the ground drops years later.
- Dumping the full depth in one go. The bottom never compacts. Place it in six to eight inch lifts.
- Compacting dry or saturated material. Dirt compacts properly only near its optimum moisture. Too dry and it will not knit; too wet and it pumps.
- Filling over topsoil or debris. Strip the organic layer first or the fill settles on top of something that is still rotting.
- Piling fill against a foundation without checking drainage. Raising grade against a wall can put water where it was never meant to go.
Frequently asked questions
How much fill dirt do I need?
Multiply length by width by the finished depth in feet and divide by 27 for cubic yards, then add about forty percent for compaction. A 40 by 30 foot pad raised a foot needs 44 cubic yards compacted, so about 62 cubic yards delivered loose.
How much does a yard of fill dirt weigh?
Screened fill dirt runs about 2,200 pounds a cubic yard, so roughly 1.1 tons. Clay is heavier at around 2,700 pounds, and any of it gets substantially heavier when wet.
What is the difference between fill dirt and topsoil?
Fill dirt is subsoil with the organic material screened out, so it compacts and stays put. Topsoil is full of organic matter, which is what makes it good for planting and bad for building on, it keeps decomposing and the ground keeps settling.
How much does fill dirt shrink when compacted?
A great deal more than most people expect. Loose fill weighs about 2,200 pounds a cubic yard and the same material compacted in the ground weighs about 3,100, so every compacted cubic yard needs roughly 1.4 loose cubic yards delivered. Thirty-five to fifty percent is the usual range, and forty percent is a fair working figure.
How deep should each lift of fill be?
Six to eight inches compacted for a plate compactor or a small roller, less for a hand tamper. Loose lifts start thicker than that and come down to the compacted thickness as they are rolled.
How much does fill dirt cost?
Material is commonly ten to twenty-five dollars a cubic yard, and delivery is often the larger part of the bill on a small order. Some contractors give clean fill away if you can take a full load, because hauling it off costs them money.
Sources and assumptions
Densities are typical values for material at ordinary moisture content. Actual weight varies a great deal with moisture and with the local soil, and any supplier can give a figure for what they are selling.
The thirty-five to fifty percent compaction range is derived from published densities rather than assumed: Caterpillar gives loose earth at 2,100 to 2,550 lb/yd³, and engineered fill compacts to roughly 110 to 120 lb/ft³ (3,000 to 3,240 lb/yd³), a ratio of about 1.4. State DOT shrinkage factors combined with Caterpillar swell figures give the same answer independently. Engineered fill under a structure is placed to a specified compaction, commonly ninety-five percent of a standard Proctor density, and that specification, not a rule of thumb, governs the work.
Truck capacities are nominal. Legal load limits vary by state and a truck is often weight-limited before it is volume-limited on heavy material.
This tool estimates material. Fill placed under a foundation, a retaining wall or a road needs engineering, testing and inspection.