Compaction Calculator

Convert in either direction between loose and compacted volume. Know the compacted base you need? Get the loose volume to order. Know how much loose material you have? See what it compacts down to.

Compaction Conversion

Compacted Volume

yd³

Compaction Factor

How much more loose material is needed than the final compacted result — typically 15% for base rock/fill, 20-30% for clay soils

Enter a known volume and compaction factor to convert.

The formula

Loose Volume = Compacted Volume × (1 + Compaction %)

Granular material loses volume when compacted as particles pack tighter. Typical compaction factors: 10–15% for well-graded crushed base rock, 15–20% for common fill, up to 25%+ for loose organic-lean soils. Your geotech report or supplier can give the exact figure for spec work.

Why this matters for ordering

Ordering the geometric volume of a base course guarantees coming up short — a 10 yd³ compacted base at 15% compaction needs 11.5 yd³ of loose material delivered. On big pours the difference is a whole extra truck.

Frequently Asked Questions

What is a typical compaction factor for base rock?

Well-graded crushed base compacts around 10–15% under proper plate or roller compaction; 15% is a safe default for ordering.

Is compaction the same as soil swell?

They’re opposite directions of the same behavior: swell is loose volume gained when excavating bank soil, compaction is loose volume lost when densifying placed material.

How do I know when material is fully compacted?

Spec projects verify with density testing (e.g., nuclear gauge) against Proctor values. For DIY work: compact in lifts of 2–4 inches until the plate compactor stops visibly settling the surface.