Glossary

Shrink factor

Shrink factor is the loss of volume when soil is placed and compacted as fill, from bank cubic yards to compacted cubic yards.

By IntelCost Team · October 7, 2026

Shrink factor is how much soil loses volume when it is placed and compacted as fill. A yard of soil cut from the bank makes less than a yard of compacted fill, so you need more cut than the fill volume on the plans.

One yard dug from the ground is not one yard in the truck or one yard in the fill.

How it works

Shrink compares bank cubic yards (BCY), soil in its natural state, with compacted cubic yards (CCY), the same soil after it is placed in lifts and compacted to spec. Compacted fill is usually denser than the bank, so the volume goes down.

The fill volume from a cut and fill calculation is a compacted volume. To know how much cut it takes, convert it back to bank yards.

Two ways shrink is written

This is where estimates go wrong. Shrink is printed two ways, and the same percentage gives two different answers:

As a loss of volume: BCY x (1 - shrink) = CCY, so BCY = CCY / (1 - shrink)
As extra cut needed: BCY = CCY x (1 + shrink)

Read the plan note or the geotechnical report to see which one is meant. If it is not clear, ask before you bid.

Example

Say the site needs 10,000 CCY of fill and the plans give a shrink of 15 percent (example values):

Method	Math	Bank yards needed
Loss of volume	10,000 / (1 - 0.15) = 10,000 / 0.85	11,765 BCY
Extra cut needed	10,000 x 1.15	11,500 BCY

The difference is 265 BCY. If the site has 11,600 BCY of usable cut, it has 100 BCY to spare one way and is 165 BCY short the other way.

Typical values

Shrink depends on the soil and on the compaction the specs require, usually written as a percentage of maximum dry density from a Proctor test. For ordinary earth, a common range is about 10 to 20 percent. Check your specs and your geotechnical report, and use their numbers when they give them. Rock can work the other way and bulk up, taking more volume as fill than it did in the bank.

Shrink is not swell

Swell is bank to loose, and it sizes the trucks. Shrink is bank to compacted, and it decides whether the site balances. The two are measured separately; you cannot work one out from the other.

Before you apply it

Take out what will not be used as fill first: topsoil that is stripped and hauled off, unsuitable material, and undercut. Apply shrink only to the soil that actually goes back in the ground. The volumes usually come from comparing two surfaces, such as TIN surfaces, so check the surfaces before you trust the balance.

In IntelCost's Earthwork tab, shrink is entered as a factor of extra cut, so 15 percent written that way is 1.15; a loss from bank of 15 percent is 1 / 0.85 = 1.18. The cut and fill guide works a full site balance with shrink applied.