Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate how much loose fill dirt to order for a project, accounting for compaction after it's tamped down.
Compacted (finished) volume before accounting for compaction: 3.704 cu yd.
Fill dirt behaves differently from gravel, sand, or mulch in one important way: once it's placed and compacted (tamped or rolled), it settles into a noticeably smaller volume than it occupied when it was loosely dumped. This calculator works backward from the finished, compacted depth you actually want to the larger loose volume you need to order to achieve it.
Enter your area and the finished (compacted) depth you want once the fill is done settling. The compaction factor -- how much the loose material shrinks -- defaults to 15%, a commonly used estimate for average soil, but actual compaction varies with soil type and how thoroughly it's tamped, so adjust it if you have better information for your specific fill material.
Compacted Volume = (Area × Finished Depth) ÷ 324
Loose Volume to Order = Compacted Volume × (1 + Compaction Factor)
Gravel, sand, and mulch are typically measured and used close to their delivered volume. Fill dirt is different: if you order exactly the volume that matches your target finished depth, you'll come up short once it's compacted, because compaction physically reduces air gaps between soil particles and shrinks the total volume. Inflating the order by the compaction factor accounts for that shrinkage in advance.
Use this when filling a low spot, building up a grade before laying a patio or driveway base, or backfilling a foundation excavation -- anywhere the finished depth matters and the fill will be compacted before anything is built on top of it.
The 15% default compaction factor is a general estimate -- sandy fill compacts less than clay-heavy fill, and how thoroughly the material is tamped or rolled also changes the real shrinkage. For a project where the finished depth is structurally important (under a foundation or driveway, for example), confirm the expected compaction rate for your specific fill material with a contractor or supplier rather than relying on a default estimate alone.
The default of 15 percent is an average, and it is worth adjusting when you know more. Using the earlier compacted volume of 3.70 cubic yards as a base, a 10 percent factor gives about 4.07 cubic yards to order, while a 25 percent factor gives about 4.63. That spread, roughly half a cubic yard on a small job, shows why the factor matters on larger projects. Try a few values to see how sensitive your order is.
Deep fill is normally placed in thin layers called lifts, with each lift compacted before the next goes on. Thick, uncompacted layers settle unevenly later, which can crack pavement or slabs built on top. This calculator handles the total volume, and it does not model lifts, but it helps to know that the compaction factor assumes the material is actually being compacted well. Lightly raked fill may compact less at first and settle more later.
Ask where the fill comes from and what it contains. Material with organic debris, trash, or large rocks can rot or settle unpredictably. For anything structural, a geotechnical engineer or your building department may specify allowed fill type, compaction percentage, and testing. Those requirements are set by local codes and site conditions, and they may not match the general estimate used here.
Because loose fill dirt compacts once tamped or rolled -- the particles settle closer together, reducing the total volume. Ordering only the "finished depth" volume would leave you short once compaction happens.
15% is a reasonable general estimate for average soil, but sandy soils typically compact less and clay-heavy soils can compact more -- if you know your specific fill material's compaction rate, use that instead.
No -- this only calculates the volume of fill dirt material needed. Compaction is typically done with a plate compactor or roller as a separate step in the project.
Estimate an average depth by measuring at several points and averaging, then use that with the total area. For a sharp dip, split the area into zones.
A small extra margin for spillage and uneven ground is common. Ask your supplier or contractor for a recommendation.
Yes, the order quantity is the loose volume that arrives on the truck, and it will shrink to your target finished depth once compacted.