When you excavate soil it loosens and takes up more space than it did in the ground. Swell is that increase. A swell of 25 percent means 100 cubic yards of bank material becomes 125 cubic yards loose in the truck. The load factor is 1 divided by (1 plus swell).

When loose soil is placed and compacted as fill, it consolidates to less than its original bank volume. Shrinkage of 10 percent means 100 cubic yards of bank material only makes 90 cubic yards of compacted fill, so you need to dig more than the fill volume suggests.

How do I convert bank to compacted?

Compacted volume equals bank volume times (1 minus shrinkage). To find how much bank material a target fill needs, divide the compacted volume by (1 minus shrinkage). The tool does both directions automatically from whichever state you enter.

Why does loose volume matter for hauling?

Trucks carry loose, swelled material, not in-place bank measure. To size your haul you must convert bank to loose first. Entering a 20 cubic yard bed, the tool divides the loose volume by 20 and rounds up to give the number of truck loads.

Where do these percentages come from?

Swell and shrinkage vary by soil. The defaults here are typical mid-range values from earthwork references: sand swells about 12 percent, common clay about 25 percent, solid rock 50 percent or more. Always use site-specific soil test data when you have it.

Earthwork Swell & Shrinkage Calculator

Soil changes volume three times during earthwork: in the ground (bank), in the truck (loose, swelled), and placed as fill (compacted, shrunk). Mixing these up is the classic earthwork error. This calculator converts cleanly between all three and estimates the truck loads to haul the loose material.

How it works

loose     = bank * (1 + swell)
compacted = bank * (1 - shrinkage)
bank      = loose / (1 + swell)  =  compacted / (1 - shrinkage)
truck loads = ceil(loose volume / truck capacity)

Swell increases volume on excavation; shrinkage decreases it on compaction. The two factors are independent properties of the soil, which is why a bank cubic yard can become both more loose volume and less compacted volume at the same time.

Example and notes

A 100 yd³ bank excavation of common clay (25 percent swell, 12 percent shrinkage) yields 125 yd³ loose — about 7 loads in a 20 yd³ truck — but only 88 yd³ of compacted fill. So if you need 100 yd³ of compacted fill, you must dig roughly 114 yd³ of bank material. Always prefer measured site soil factors over these typical defaults for any real bid.