Soil Compaction Calculator
Enter your soil volume, its starting state, and the state you need it converted to — bank (in-situ), loose (excavated), or compacted (placed).
Swell/shrink percentages are typical values — confirm with a geotechnical report for engineered fills.
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Soil notes
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Details
For the default 10 yd³ of loam measured in its bank (in-situ) state, converting to compacted (placed) volume using a 12% shrink factor gives 8.80 yd³ once it’s spread and compacted.
Volume conversions for common soil types
Each soil type uses its own swell and shrink percentages, since sand, loam, clay, and gravel behave differently when dug and compacted.
| Soil type | Starting volume & state | Target state | Converted volume |
|---|---|---|---|
| Clay | 15 yd³ (bank) | Loose (excavated) | 19.50 yd³ |
| Sand / granular fill | 20 yd³ (loose) | Bank (in-situ) | 17.86 yd³ |
| Loam / average topsoil | 12 yd³ (bank) | Compacted (placed) | 10.56 yd³ |
| Gravel / crushed stone | 8 yd³ (bank) | Compacted (placed) | 7.28 yd³ |
| Clay | 25 yd³ (loose) | Compacted (placed) | 15.38 yd³ |
| Loam / average topsoil | 30 yd³ (bank) | Loose (excavated) | 36.00 yd³ |
How to calculate soil compaction volume
- Pick your soil type. Sand, loam, clay, and gravel each have their own typical swell and shrink percentages — clay swells and shrinks the most, gravel the least.
- Enter your known volume and its current state. State it as bank (undisturbed, in-situ), loose (already excavated or delivered loose), or compacted (already placed and compacted).
- Convert back to a bank-equivalent volume first. Divide the input volume by that state’s factor (1 for bank, 1+swell% for loose, 1−shrink% for compacted) to find the underlying undisturbed volume.
- Pick the state you need the answer in. Choose bank, loose, or compacted depending on whether you’re planning excavation, ordering delivered fill, or estimating a finished compacted volume.
- Multiply the bank-equivalent volume by the target factor. Multiplying by the target state’s factor converts the bank-equivalent volume into your answer in that state.
Worked example
Using the calculator’s defaults: 10 yd³ of loam, entered in its bank state, converted to compacted state.
- Soil typeLoam / average topsoil (swell 20%, shrink 12%)
- Input volume & state10 yd³ (bank)
- Bank-state factor1.00
- Bank-equivalent volume (10 ÷ 1.00)10.00 yd³
- Target stateCompacted (placed)
- Compacted-state factor (1 − 12% shrink)0.88
- Output volume (10.00 × 0.88)8.80 yd³
Understanding bank, loose, and compacted soil
The same soil takes up a different amount of space depending on whether it’s undisturbed, freshly dug, or packed down — knowing which state you’re measuring matters.
- Bank (in-situ) measure.Soil as it sits naturally in the ground, undisturbed — this is the reference state both swell and shrink factors are calculated from.
- Loose (excavated) measure.Soil right after it’s dug up — it expands from its bank volume by the swell percentage because digging breaks up its natural packing.
- Compacted (placed) measure.Soil after it’s spread in its final location and mechanically compacted — it ends up smaller than its bank volume by the shrink percentage.
- Why swell matters for hauling.Trucks and dumpsters are loaded with loose soil, so haul-off and delivery quantities should always be estimated in loose volume, not bank volume.
- Why shrink matters for fill orders.A finished compacted fill volume needs more loose material delivered than the finished number suggests — order based on the loose-equivalent volume.
- Why soil type changes the numbers.Clay’s fine particles trap more air when dug and compress more under compaction than sand or gravel, giving it the largest swell and shrink percentages of common soils.
Common mistakes
- Assuming volume stays the same across states.A cubic yard of bank soil is not a cubic yard once it’s dug (loose) or once it’s compacted (placed) — always convert through the correct factor.
- Using one soil type's factors for another.Clay, loam, sand, and gravel each swell and shrink differently — using generic factors can throw off volume estimates by 10-20%.
- Ordering fill by finished (compacted) volume.Suppliers sell loose material by the yard — order the loose-equivalent volume, not the smaller compacted volume you’re aiming for.
- Estimating haul-off trucks from bank volume.Excavated soil expands once dug — basing truck counts on the undisturbed bank volume under-orders hauling capacity.
- Converting in the wrong direction.Always convert through the bank-equivalent volume as an intermediate step — going straight from loose to compacted (or vice versa) without it gives the wrong answer.
- Ignoring moisture content.Wet soil compacts differently than soil at optimal moisture — field compaction results can vary from these standard percentage-based estimates.
What this calculator assumes
Adjust your result if your project differs from these.
- Swell and shrink percentages are typical published values for each general soil category — actual site soil can vary.
- Bank (in-situ) volume is treated as the reference state with a factor of 1.00.
- Loose volume equals bank volume multiplied by 1 plus the swell percentage.
- Compacted volume equals bank volume multiplied by 1 minus the shrink percentage.
- Compaction is assumed to be done at or near optimal moisture content with standard equipment.
- Results are volume estimates for planning — engineered fill projects should confirm compaction requirements with a geotechnical report.
Common questions
What's the difference between bank, loose, and compacted soil?
Bank is undisturbed soil in the ground, loose is soil after it’s dug up and expanded, and compacted is soil after it’s placed and mechanically packed down.
Why does soil volume increase when you dig it up?
Digging breaks up the soil’s natural packing and traps air between particles, causing it to expand — this is called swell.
Why does soil volume decrease when you compact it?
Compaction squeezes out air pockets and packs particles tighter than their natural (bank) state, reducing volume below the original — this is called shrink.
Which soil type swells the most when excavated?
Clay typically has the highest swell percentage of common soils, often around 25-35%, due to its fine particle structure.
How much fill should I order for a compacted volume?
Divide your target compacted volume by (1 − shrink %) to get the bank-equivalent, then multiply by (1 + swell %) if you’re ordering it as loose delivered material.
Do sand and gravel compact more predictably than clay?
Yes — granular soils like sand and gravel have lower swell and shrink percentages and compact more consistently than fine-grained clay.
Can I convert directly between loose and compacted volume?
Yes — the calculator converts through the bank-equivalent volume automatically, so you can enter any state and convert to any other.
Does moisture content affect these calculations?
Yes, in practice — these percentages are typical estimates; actual compaction results depend on moisture content and compaction effort in the field.
Why do suppliers sell soil and mulch by loose volume?
Because that’s the volume it occupies in a truck or pile at delivery — it’s the practical, measurable state for buying and selling bulk material.
Is 12 yd³ a standard soil delivery size?
It’s a common single-axle dump truck capacity, but delivery sizes vary by supplier and vehicle — confirm your hauler’s actual load size.
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Soil Compaction Calculator Result
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Result
| Input | — |
| Soil type | — |
| Bank | — |
| Loose | — |
| Compacted | — |
Notes
Estimate generated by materialcalculate.com.