Cut and fill takeoff: where shrink and swell eat your margin

A cut and fill takeoff produces one number that everybody looks at — the balance — and three numbers that decide whether it is true. If bank, loose, and compacted yards get mixed together anywhere in that chain, the balance is fiction, and the first thing you find out is that you are trucking material you did not price.

Three yards, three meanings

The same dirt measures differently depending on where it is standing:

• Bank cubic yards (BCY) — in place, undisturbed, the way the surveyor found it. This is what your takeoff surfaces produce.
• Loose cubic yards (LCY) — in the truck, after it swells. This is what you haul and what you pay for by the load.
• Compacted cubic yards (CCY) — in the fill, after it shrinks. This is what the spec asks you to place.

Swell is the increase from bank to loose. Shrink is the decrease from bank to compacted. They are different factors, they move in opposite directions, and neither one is optional.

Rough starting points, subject to your geotech report and your own history in that dirt:

Material	Swell (bank → loose)	Shrink (bank → compacted)
Common earth / loam	20–25%	10–15%
Sand and gravel	10–15%	5–12%
Clay	25–35%	15–25%
Weathered rock	30–40%	Placed as fill, varies widely
Solid rock	50–65%	Not applicable

Those are ranges, and the range matters more than the midpoint. On 20,000 yards of clay, the difference between 15% and 25% shrink is 2,000 compacted yards you either have or do not.

Where the error actually enters

Almost nobody gets this wrong in principle. It goes wrong in three specific places.

The balance is computed in mixed units

The plans give you cut and fill as neat volumes. If the takeoff says 18,000 CY cut and 18,000 CY fill, that reads as a balanced site — right up until you notice the cut is bank measure and the fill is compacted measure. Apply 15% shrink and 18,000 bank yards places about 15,300 compacted yards. You are 2,700 yards short, and that shortfall is import: material, trucking, and placement, none of which is in the bid.

Convert everything to a common basis before you subtract. Bank is usually the right basis, because that is what your cut production rates are built on.

Topsoil is counted twice, or not at all

Six inches of strip over ten acres is roughly 8,000 bank yards. That volume is frequently sitting inside the cut number and handled again as a separate strip line, which double-counts it — or it is stripped, stockpiled, and respread without anyone deducting it from the material available for structural fill, which under-counts your import.

Decide once whether topsoil is inside or outside the mass volume, write it on the takeoff, and hold to it.

Unsuitable material is treated as available

Soft, wet, or organic material shows up in the cut volume like anything else, and the geotech report says it cannot go in structural fill. That converts it in one step from "material I have" to "material I pay twice for" — once to haul off, once to import its replacement.

If the boring logs flag it and you did not price it, that is not a change order, that is your money. Read the boring logs before the takeoff, not after the debrief.

Price the trucking off loose yards

Once the balance is right, the haul is straightforward, and it is worth being deliberate because trucking is often the single largest line on a grading bid.

loads = (bank yards × swell factor) ÷ truck capacity
cost  = loads × cycle time × truck rate     (or loads × per-load rate)

A tri-axle at 14 loose yards moving 5,000 bank yards of clay at 30% swell is 6,500 loose yards, or 465 loads — not the 358 loads you would get by dividing bank yards straight into truck capacity. That is 107 loads of difference, and at $95 a load it is about $10,000 on one line item.

Cycle time is the other half, and it is a site question, not a spreadsheet question: haul distance, road speed, load and dump time, and how many trucks the excavator can actually keep fed. An excavator loading at four minutes a truck cannot use ten trucks on a fifteen-minute round trip, and paying for trucks that sit is a real cost that never shows up in a per-yard price.

Keep the assumptions attached to the number

The thing that makes a shrink and swell factor defensible six months later is the note next to it. When the GC asks why your import number is 3,200 yards and the low bidder's is 900, you want to be able to say which factor you used, on which material, from which boring log — not go re-derive it from a spreadsheet whose formulas nobody has looked at since the bid.

Write it on the line item:

Import 3,200 CY structural fill — balance shortfall at 15% shrink on clay per B-4/B-7, excludes 6" topsoil (stockpiled, respread).

That single sentence is worth more at a scope review than the entire rest of the estimate, because it is the one that shows the number came from somewhere.

The short version

• Convert cut and fill to a common basis — usually bank — before you compute the balance.
• Use the geotech report's material description, not a default factor, and record which one you used.
• Decide once whether topsoil lives inside or outside the mass volume.
• Deduct unsuitable material from what is available before you call the site balanced.
• Price haul off loose yards and check that your truck count matches what the loader can feed.

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In DirtIQ, an AGTEK volume report imports straight into the estimate as grading line items, so cut, fill, strip, and import loads arrive as the quantities the takeoff actually produced instead of numbers retyped at eleven at night. From there they price against your own production rates and crew costs.