Bank Cubic Yard Calculator: How to Measure

A bank cubic yard (BCY) calculator converts the volume of soil, rock, or other material in its natural, undisturbed state (bank) to the volume it will occupy after excavation (loose) or after compaction (compacted). You enter the bank volume and select the material type, and the calculator returns the loose and compacted volumes using standard swell and shrinkage factors. This is essential for estimating hauling costs, landfill space, and fill requirements in earthmoving projects.

Formula

The calculator uses two standard relationships in earthmoving:

• Loose volume = Bank volume × Swell factor (always > 1)
• Compacted volume = Bank volume × Shrinkage factor (usually < 1)

Where:

• Bank volume (v) is the volume in its natural state, in cubic yards (yd³).
• Swell factor (mat) is the ratio of loose volume to bank volume, varying by material (e.g., 1.25 for sandy soil means it expands 25% when excavated).
• Shrinkage factor is the ratio of compacted volume to bank volume (here assumed 0.85, meaning 15% reduction).

Worked Example

Using the default values: bank volume = 100 yd³, material = sandy soil (swell factor = 1.25).

1. Loose volume = 100 × 1.25 = 125 yd³
2. Compacted volume = 100 × 0.85 = 85 yd³

The calculator shows: Loose volume = 125.00 yd³, Compacted volume = 85.00 yd³.

When to Use a Bank Cubic Yard Calculator

Use this calculator whenever you plan to excavate, move, or place earth. Common scenarios include:

• Estimating truckloads needed to haul away excavated soil (loose volume determines the number of loads).
• Calculating how much fill material to order for a compacted embankment or foundation (compacted volume matters).
• Comparing cut and fill volumes on a site to minimize import/export.
• Budgeting for earthwork in construction, landscaping, or mining.

How to Read the Results

The loose volume is what you’ll actually handle during excavation—it dictates truck size, number of hauls, and spoil area. The compacted volume is what remains after placing and compacting, which is critical for achieving the required grade or density. Always order or plan for the loose volume when transporting, but specify the compacted volume when designing a fill.

Common Mistakes and Misconceptions

• Confusing bank and loose volumes: A yard of bank soil is not the same as a yard of loose soil. Swell can be 15–50% depending on material.
• Using a single factor for all materials: Swell factors vary widely—clay swells more than gravel, and rock can swell up to 50% or more.
• Ignoring compaction: Compaction reduces volume below bank, which is why you need more bank material than the final fill volume.
• Unit mix-ups: Always work in cubic yards or convert from cubic meters (1 m³ = 1.30795 yd³).

Limits of the Formula

This calculator provides a rough estimate. Real-world swell and shrinkage depend on moisture content, grain size, compaction method, and depth of fill. For critical projects, consult geotechnical data or perform field tests. The calculator assumes a uniform material and does not account for losses during transport or placement.

Frequently Asked Questions

What is a bank cubic yard?

A bank cubic yard (BCY) is the volume of material as it exists in place, in its natural state, measured in cubic yards. It is the baseline for all earthwork calculations.

Why does soil swell when excavated?

When soil or rock is removed from its natural state, the particles are separated and air fills the voids, increasing the total volume. This expansion is called swell and is expressed as a percentage (e.g., 25% swell means the loose volume is 1.25 times the bank volume).

How do I convert bank cubic yards to loose cubic yards?

Multiply the bank volume by the swell factor. For example, 100 BCY of clay (swell factor 1.35) becomes 135 loose cubic yards (LCY).

What is the difference between bank, loose, and compacted cubic yards?

Bank is the natural in-place volume. Loose is after excavation and loading (always larger). Compacted is after placement and compaction (usually smaller than bank). Each is used for different purposes: bank for cut/fill calculations, loose for hauling, compacted for final fill specifications.

Can I use this calculator for rock?

Yes, but rock swell factors can be as high as 1.5 or more, and the calculator’s “Rock� option uses 1.50. For large boulders or blasted rock, the loose volume may be even greater due to irregular shapes and voids.

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in v | Bank volume | yd³ | 100 | 0
sel mat | Material | Sandy soil=1.25, Clay soil=1.35, Gravel=1.15, Rock=1.50, Mixed=1.30
out loose | Loose volume | yd³ | v * mat | 2
out compacted | Compacted volume | yd³ | v * 0.85 | 2