Soil Volume Calculator: Bank, Loose, and Compacted Yards
The same "dirt" has three different volumes depending on where it is in the earthmoving process. Earth in the ground referred to as "Bank" . Once the dirt is disturbed through excavation it is "Loose". When that same dirt is packed into a fill it is "Compacted".
Mix those up on a bid and you either come up short on haul trucks or buy borrow you never needed. This calculator will help you keep them straight. Put in a volume, pick the material, and you get bank, loose, and compacted side by side. Enter your own material types and densities per your soils proctor or you experience. As always, double check your calculations.
More on earthmoving math and how the calculator works below....
Why One Yard is Never Just a Yard
When you dig bank material out of the ground it breaks apart and traps air taking up more room than it did in place. That expansion is referred to as swell. When it is in this state, during the hauling/pushing process the dirt is referred to as loose fill. When you spread that same material in lifts and roll many materials pack down tighter than its bank state. That reduction is shrinkage. Both are the reason the cut and fill numbers you scale off the plans are almost never the numbers you actually haul and place.
In earthwork you often haul more than you excavate and pack in less than you hauled! Confusing, but makes sense when you look at each step in the process.
How the Math Works
Loose yards = bank yards x (1 + swell factor). Compacted yards = bank yards x (1 - shrink factor).
Say you have 1,000 bank yards of common earth. At a 25 percent swell, that is 1,250 loose yards in the trucks -- that is the number you use to count loads. At a 10 percent shrink, that same dirt fills only 900 yards of compacted fill. One number on the plans, three numbers that effect different phases of the earthmoving process.
Rock runs backward. Blasted rock bulks so much that even after placement it takes up more room than it did in the ground, so its shrink factor is negative. The calculator flags that so it does not read like a mistake.
About the Materials and Factors
The factors that load in by material are typical starting points, sourced from the Caterpillar Performance Handbook, Edition 48. They are not gospel. Swell and shrink move with moisture, soil makeup, lift thickness, and how well you compact. That is why every factor in the tool is editable. Drop in your own tested numbers or hard earned experience and the results follow. On a real bid, trust your field data over any table.
Jump back to our Free Tools page for other helpful calculators and information contractors need every day.
Common Questions About Soil Volumes
Q: What is the difference between bank, loose, and compacted cubic yards?
A: Bank yards are the material as it sits undisturbed in the ground. Loose yards are that same material after it is dug and hauled, it has expanded and taken on air. Compacted yards are the material after it is placed and rolled in a fill, packed tighter than its bank state. One bank yard, one loose yard, and one compacted yard are three different volumes of the same dirt.
Q: What is a swell factor in earthwork?
A: A swell factor is the percent a material expands when dug out of the ground. Loose volume equals bank volume times one plus the swell factor. Clay with a 22 percent swell turns 1,000 bank yards into 1,220 loose yards in the trucks. Swell varies by material, moisture, and how the soil is excavated, so published tables are a starting point, your proctor or local experience is valuable when it comes to swell factors.
Q: What is a shrinkage factor in earthwork?
A: A shrinkage factor is the percent a material loses when compacted in a fill compared to its bank volume. Compacted volume equals bank volume times one minus the shrinkage factor. Blasted rock and some hard materials are exceptions, they bulk so much that even after placement they take up more room than they did in the ground, so their shrinkage factor runs negative.
Q: How do I convert bank yards to loose yards for haul calculations?
A: Multiply bank yards by one plus the swell factor. That gives you loose yards, which is the number you use to count truck loads. Enter your bank volume in the calculator, pick the material, and the loose figure is calculated automatically. You can also enter a loose or compacted volume and work backward to bank.
Q: Where do the swell and shrinkage factors in this calculator come from?
A: The preset factors are sourced from the Caterpillar Performance Handbook, Edition 48, Table 30-6, a standard reference for earthmoving estimating. Swell factors are derived from the published load factors in that table. All fields are editable, so you can plug in your own values when field data is available.
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