Bank, loose and compacted
- Bank cubic yards (BCY) are the dirt as it lies in the ground. Plans and cut quantities are in bank yards.
- Loose cubic yards (LCY) are the same dirt dug up, in a truck or a stockpile. It grows by its swell: loose = bank × (1 + swell).
- Compacted cubic yards (CCY) are the dirt placed and compacted in a fill. It ends up smaller than it lay by its shrink: compacted = bank × (1 − shrink). Blasted rock is the exception: it compacts bigger than it lay.
The load factor is the other way round: bank yards in each loose yard, 1 ÷ (1 + swell). A truck carrying 16 loose yards of dry clay is moving 11.2 bank yards. Weight doesn't change from state to state, so tons come from the bank volume and the bank weight.
Swell and shrink factors by soil
| Material | Bank → loose | Bank → compacted | Swell | Shrink | Load factor | Bank lb/yd³ |
|---|---|---|---|---|---|---|
| Common earth (loam), dry | 1.25 | 0.90 | 25% | 10% | 0.80 | 2,180 to 2,980 |
| Common earth (loam), wet | 1.25 | 0.90 | 25% | 10% | 0.80 | 3,500 to 4,000 |
| Clay, dry | 1.43 | 0.90 | 43% | 10% | 0.70 | 2,360 to 2,780 |
| Clay, wet | 1.43 | 0.90 | 43% | 10% | 0.70 | 3,360 to 4,200 |
| Sand or gravel, dry | 1.11 | 0.95 | 11% | 5% | 0.90 | 2,860 to 3,450 |
| Sand or gravel, wet | 1.11 | 0.95 | 11% | 5% | 0.90 | 3,080 to 3,560 |
| Rock, blasted | 1.50 | 1.30 | 50% | -30% | 0.67 | 4,000 to 5,300 (shale, trap rock) |
Volume factors from FM 5-434 Table 1-1, which doesn't split by moisture; weights from its Table 1-2. Other published tables give different figures for the same soil (clay swell is quoted anywhere from about 20% to 45%), which is why a test on your own dirt is worth having.
A worked example
A building pad needs 1,000 compacted yards of fill from a borrow area of dry clay (1.43 bank to loose, 0.90 bank to compacted):
- Bank yards to dig: 1,000 ÷ 0.90 = 1,111.
- Loose yards to haul: 1,111 × 1.43 = 1,589, which is what the trucks have to carry.
- Weight: 1,111 × 2,570 lb ÷ 2,000 = 1,428 tons.
Bidding the fill at its compacted volume would leave out the 111 yards it shrinks and the 589 extra yards of hauling. The haul calculator turns the loose yards into loads and trucks, and Site Bid carries shrink and swell factors on every earthwork quantity.
Sources
- US Army FM 5-434, Earthmoving Operations (2000), Table 1-1 (material volume conversion factors) and Table 1-2 (weights, swell and load factors). Approved for public release. Read the manual. Checked October 3, 2026.
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