Soil Compaction Calculator

About the Soil Compaction Calculator

Converts between loose (bank) and compacted soil volumes using a compaction factor, helping you order the right amount of fill.

How to use this calculator

1. Enter the loose soil volume and the compaction percentage.
2. If needed, enter the compacted volume instead, depending on which value the calculator asks for.
3. Check the result for the converted volume, either compacted or loose.
4. Use the step-by-step output to see how the volume changed.

The formula explained

This calculator compares loose soil volume and compacted soil volume using a compaction percentage. In general, compacted volume is found by multiplying loose volume by the remaining fraction after compaction, and loose volume can be found by reversing that relationship.

• \(V_{loose}\) = the soil volume before compaction
• \(V_{compacted}\) = the soil volume after compaction
• p = the compaction percentage
• f = the remaining fraction after compaction, written as \(f = 1 - \frac{p}{100}\)

Step by step method

1. Convert the compaction percentage to a decimal fraction by dividing by \(100\).
2. Find the remaining fraction of volume after compaction using \(1 - \frac{p}{100}\).
3. Multiply the loose volume by that fraction to get compacted volume, or divide by that fraction to recover loose volume.
4. Check that the result makes sense, because compacted soil should usually take up less space than loose soil.

Worked example

Problem. A contractor has \(12\) cubic yards of loose soil, and the soil compacts by \(20\%\). What is the compacted volume?

1. First find the remaining fraction, \(1 - \frac{20}{100} = 0.8\).
2. Multiply the loose volume by \(0.8\), so \(12 \times 0.8 = 9.6\).
3. The compacted volume is \(9.6\) cubic yards.

Tips and common mistakes

• Be careful to use the correct percentage, because a small change in compaction can change the final volume a lot.
• Make sure your units stay the same, such as cubic feet or cubic yards, from start to finish.

Frequently asked questions