Calculate the compacted volume you need — length × width × depth in feet ÷ 27 — then add 20% so you still hit grade after the plate compactor. A 20 × 10 ft pad finished at 4 inches needs about 2.5 compacted cubic yards, so order roughly 3 loose cubic yards, or 4.6 tons of crusher run.
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Order – tons (includes your waste allowance) so compaction and spillage don’t leave you short.
Stone Compaction Calculator Guide
There are two volumes in every base project: the loose volume that comes off the truck and the compacted volume that ends up under your driveway. The plate compactor eats the difference. This calculator works from the finished, compacted dimensions you actually need and adds a 20% allowance by default, so the loose material you order still reaches grade once it has been tamped tight.
Skip that step and the shortfall is predictable: a base planned at 4 inches, ordered without an allowance, finishes at about 3¼ inches after compaction. The missing three-quarters of an inch then costs a second delivery fee — the most expensive stone you will ever buy.
How Much Volume Does Stone Lose When Compacted?
Shrinkage depends almost entirely on fines content. Material full of dust has the most rearranging to do under vibration; clean washed stone has almost none.
| Material | Typical volume loss | Order extra |
|---|---|---|
| Crusher run / dense-graded base | 15–20% | 20% |
| Dense-graded limestone | 15–20% | 20% |
| Crushed stone (general) | 10–15% | 15% |
| Stone dust / screenings | 10–15% | 15% |
| Crushed concrete | 10–15% | 15% |
| Round gravel | 5–10% | 10% |
| Washed #57 / #67 | About 5% | 5% |
Getting Full Density in the Field
Compaction is depth-limited: a typical plate compactor only drives energy 2–3 inches down. Spread a 6-inch base in one lift and the top tightens while the bottom stays fluffy, then settles under traffic a year later. Place 2-inch lifts instead, compacting each with three or four overlapping passes before the next goes down. Moisture matters too — dense-graded stone compacts best slightly damp, when the fines slide into the voids instead of dusting away, so mist each lift in dry weather.
You can check your work without instruments. Walk the surface: boot heels should leave no impression, and a final compactor pass should visibly stop moving material. If the plate still sinks or the surface pumps, the layer either needs more passes or is too wet to lock.
The allowance here covers compaction only — irregular subgrades and over-excavation can add more. For the standard dense-graded material this math assumes, see the crusher run calculator, and for a full paver base build with bedding layers on top, the paver base calculator carries the same compaction logic through the whole stack.
Frequently Asked Questions
How much does crusher run compact?
Dense-graded crusher run typically loses 15–20% of its loose volume under a plate compactor as the fines settle into the voids. That is why this calculator defaults to a 20% allowance instead of the usual 10%.
Does washed stone like #57 compact?
Barely — around 5%. Washed stone has no fines to migrate into the voids, so it seats slightly under vibration and then stops. Its volume is essentially what you pour in.
Do suppliers sell loose or compacted volume?
Loose. The truck is loaded with fluffed material straight off the stockpile, but your plans specify compacted depth. The gap between the two is the compaction allowance, and forgetting it is the most common reason bases come up short.
What is the best way to compact stone?
Spread in 2-inch lifts, lightly mist each lift so the fines lubricate and lock, and make 3–4 overlapping passes with a plate compactor before adding the next lift. One thick lift compacted from the top leaves the bottom loose.