Convert bank cubic yards to loose CY (after excavation) and compacted CY (after placement) using swell and shrinkage factors by soil type. Essential for earthwork bidding and truck load planning.
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Shop Express Tools →Every earthwork project deals with three distinct volume states. Bank measure (BCY) is the in-situ volume — what the plans show and what you bid. Loose measure (LCY) is the volume after excavation and loading — what fills the truck. Compacted measure (CCY) is the final placed volume — what goes in the embankment or fill.
Getting swell wrong on a large excavation means your truck count is off, your spoil disposal cost is wrong, and your schedule slips. Getting shrinkage wrong means you ordered too little fill material and the embankment comes up short. On a 10,000 BCY clay excavation at 30% swell, you're actually handling 13,000 loose CY — that's 33% more truck trips than the bank CY number suggests. Always convert to the appropriate measure for each part of the job.
The factors in this calculator are industry averages suitable for estimating and preliminary planning. For large earthwork contracts (say, over 5,000 CY), request the geotechnical investigation report. It will have laboratory density tests that let you calculate project-specific swell and shrinkage factors from the actual soil bank density and the achieved compacted density from the Proctor test. This eliminates guesswork on major bids.
Swell factor is the percentage increase in soil volume when it is excavated from its natural, in-ground (bank) state and placed loose. When soil is disturbed, the particles separate and air voids increase. A 30% swell factor means 100 bank CY becomes 130 loose CY. This affects truck payload planning and spoil disposal calculations.
Shrinkage factor is the percentage decrease in volume when soil is placed and compacted from its bank (in-ground) state. Compaction removes air voids and densifies the material. A 10% shrinkage factor means 100 bank CY yields only 90 compacted CY. This is critical for fill volume calculations — you need more bank CY to achieve the required compacted volume.
Typical swell factors: Clay — 25–40% (average 30%); Sand — 10–15% (average 12%); Gravel — 10–15% (average 12%); Rock (blasted) — 30–65% (average 50%); Topsoil — 20–30% (average 25%); Common fill/silt — 15–25% (average 20%). These are industry averages; actual values depend on density and moisture content.
Multiply the truck box capacity in CY by the load factor (Bank CY ÷ Loose CY = 1 / (1 + swell)). For clay at 30% swell, the load factor is 1/1.30 = 0.769. A 14 CY truck hauls 14 × 0.769 = 10.8 bank CY per load. Alternatively: bank CY per load = truck capacity ÷ (1 + swell factor).
Intact rock is very dense with minimal void space. When blasted or ripped, it breaks into irregular chunks with large air voids between pieces. Solid granite (160+ pcf bank) breaks into rubble that weighs only 95–110 pcf loose — a 50% or greater volume increase. This means a rock cut that appears manageable becomes a much larger spoil pile after blasting.
Volume measured in its natural, in-ground state
Swell: 30% · Shrinkage: 10%
| Soil Type | Swell Factor | Shrinkage Factor | Load Factor (Loose/Bank) |
|---|---|---|---|
| Clay | 30% | 10% | 0.769 |
| Sand | 12% | 8% | 0.893 |
| Gravel | 12% | 8% | 0.893 |
| Rock | 50% | 30% | 0.667 |
| Topsoil | 25% | 15% | 0.800 |
| Common Fill / Silt | 20% | 10% | 0.833 |
Load factor = Bank CY ÷ Loose CY. Used for truck payload calculations.