CalculatorAsphalt

Swell Factor Calculator

Compute swell percentage from bank and loose volumes, or convert between them.

Quick answer: Swell % = (loose − bank) ÷ bank × 100. Sand runs 10–15%, common earth 20–30%, dense clay 30–40%, blasted rock 40–50%. Use it to convert bank takeoffs into haul volumes.

How to use this calculator

  1. Enter Bank volume in cu yd.
  2. Enter Loose volume in cu yd.
  3. Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.

Formula & constants

Swell % = (loose − bank) ÷ bank × 100. Sand runs 10–15%, common earth 20–30%, dense clay 30–40%, blasted rock 40–50%. Use it to convert bank takeoffs into haul volumes. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.

Worked example. With bank volume = 10 cu yd, loose volume = 10 cu yd, the calculator returns:
Swell factor0.0 %
Load factor1.000

Where this fits in the project

Earthwork precedes everything: dig volumes set the budget for hauling and determine imported fill or base gravel. Bank volume expands when dug (swell) and imported fill shrinks when compacted — use the truckload calculator on loose volume, not bank volume.

How this connects to your project

No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the swell factor calculator:

Frequently asked questions

What is a load factor?

Bank ÷ loose volume — multiply truck capacity by it to get bank yards per load.

Does soil return to bank density when compacted?

It goes denser — compacted fill shrinks below original bank volume, which is why shrink and swell are tracked separately.

Last verified: — prices reflect current national averages. See our methodology.

Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.