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PlanQty

Shrink/Swell Calculator

Apply swell when material is excavated (bank to loose) and shrink when it is compacted (bank to compacted). Use it before ordering trucks or import fill.

In-place, before excavation

%

Bank to loose. 0 if not hauling.

%

Bank to compacted. 0 if not placing fill.

Enter your values, then press Calculate.

How to calculate

Enter in-place bank cubic yards. Swell is typical 10–40% for soils (higher for riprap and rock). Shrink is the loss from bank to compacted in-place; 10–20% is common for many fills. Both may be zero if you only need one conversion.

Formula

Loose yd³ = bank yd³ × (1 + swell%/100). Compacted yd³ = bank yd³ × (1 − shrink%/100). Load factor = loose ÷ bank.

Common use cases

  • Spoils haul volume
  • Import fill after compaction
  • Comparing cut vs fill
  • Checking a geotech swell table

Assumptions

  • Bank volume is in-place material before you disturb it.
  • Swell percent increases bank to loose (what you haul).
  • Shrink percent decreases bank to compacted fill (what you need from a pit for a finished section).
  • The two factors are independent. You can run swell only, shrink only, or both.

Limitations

  • Does not look up a soil name. AASHTO or USCS labels are not inputs.
  • Does not replace a proctor or a geotech swell test.
  • Does not count trucks. Pass loose yards to the truckload estimator.
  • Does not compute the trench prism. Start from a known bank volume.

Worked examples

100 bank, 25% swell, 10% shrink

Shows both conversions on the same bank quantity: 125 loose yd³ to haul, and 111.1 bank yd³ of borrow if 10% shrink applies to a fill.

  1. 1. Apply swell

    100 × (1 + 25%) = 125 yd³

  2. 2. Apply shrink

    100 × (1 − 10%) = 90 yd³

Swell only

  1. 1. Apply swell

    80 × (1 + 20%) = 96 yd³

  2. 2. Apply shrink

    80 × (1 − 0%) = 80 yd³

Two conversions, two questions

Swell answers how much loose material you haul: loose yards = bank × (1 + swell/100). Shrink answers how much bank you need to end up with a compacted fill: compacted yards = bank × (1 − shrink/100) when you start from bank, or invert that when you know the compacted pay quantity. Do not chain swell and shrink into one mystery factor unless the geotech report says to.

Where truckload and spoils fit

Trench spoils is the same swell step specialized to a trench bank volume plus a truck count. This page is the general bank/loose/compacted converter when you already have a yardage from a site cut, a borrow pit, or a trench takeoff. Count trucks from loose yards, not bank yards.

Haul and borrow are opposite directions

One hundred bank yards at 25% swell is 125 loose yards to haul off. The same 100 bank yards at 10% shrink means you need 111.1 bank yards from a pit to end up with 100 compacted yards in place (100 ÷ 0.90). Mixing those — applying swell to an import borrow — will overstate trucks. Spoils going off site use swell; import coming on site for compacted fill uses shrink.

Related calculators

FAQ

Are swell and shrink applied together?

They answer different questions. Swell is for hauling excavated material. Shrink is for how much bank you need to end up with a compacted fill. Do not chain them into one mystery factor unless your geotech says to.

Where do the percentages come from?

Use the geotech report, borrow-pit history, or typical ranges for that soil. The calculator does not invent a factor from the soil name.

Which number do I give the trucking company?

Loose yards after swell, then whole trucks from the truckload page. They are not hauling bank yards.

Can shrink be applied to spoils I am wasting?

Usually no. Wasted spoils are loose. Shrink matters when you are buying material that must compact to a finished section.

Disclaimer

These calculators are estimating tools for planning and field checks. They are not a substitute for approved plans, specifications, licensed professional engineering, or governing standards. Confirm densities, waste factors, and yields with your supplier and project documents.