Boneyard Tools

Soil Swell and Shrinkage Calculator

Enter a soil quantity in any one state, bank, loose or compacted, along with the swell and shrinkage percentages. The calculator converts to the other two states in cubic yards.

How to convert soil volume states

  1. Pick whether you know the bank, loose or compacted volume.
  2. Enter that volume in cubic yards.
  3. Set the swell and shrinkage percentages, then read the other two states.

Examples

Bank to loose and compacted

bank = 100 cy, swell 25%, shrinkage 10%
loose 125 cy, compacted 90 cy

Loose back to bank

loose = 125 cy, swell 25%
bank 100 cy, compacted 90 cy

Frequently asked questions

What are bank, loose and compacted volumes?

Bank is undisturbed soil in place. Loose is the same soil after excavation, which takes up more space. Compacted is soil placed and compacted in fill, which takes up less space.

What is the swell factor?

Swell is the volume increase from bank to loose. At 25% swell, 100 bank cubic yards become 125 loose cubic yards, because digging adds voids and air to the soil.

What is the shrinkage factor?

Shrinkage is the volume decrease from bank to compacted. At 10% shrinkage, 100 bank cubic yards become 90 compacted cubic yards once placed and compacted in fill.

How do I convert loose volume back to bank?

Divide the loose volume by one plus the swell fraction. With 25% swell, 125 loose cubic yards divided by 1.25 equals 100 bank cubic yards.

Why must shrinkage be less than 100 percent?

Compacted volume is bank times one minus the shrinkage fraction. At 100% shrinkage that would be zero or negative volume, which is impossible, so the calculator rejects it.

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