Earthwork volume calculator
Soil swells when dug, so loose volume is bank volume times (1 + swell %). Compacted soil shrinks, so compacted volume is bank volume times (1 - shrinkage %). Truck runs are the loose volume divided by the truck capacity, rounded up. The soil figures are typical, so check your geotechnical report.
On this page
Bank, loose and compacted
Soil is measured in three states. Bank volume is the soil in place. Loose volume is the same soil after excavation, when it has swelled. Compacted volume is the soil after it has been placed and compacted. Swell and shrinkage are both measured from the bank volume, so a bank cubic metre becomes 1 + swell loose cubic metres, and 1 - shrinkage compacted cubic metres.
Enter length, width and depth in metres. With a side slope of 1 : n, the calculator treats length and width as the bottom dimensions and widens the cut as it rises: volume = L x W x D + n x D^2 x (L + W) + 4/3 x n^2 x D^3. With n = 0 the sides are vertical and the volume is simply L x W x D.
Typical figures, and why to check them
The soil type fills in typical swell and shrinkage, which you can overwrite. Leave a box blank to use the typical figure, or type any number, including 0. The typical figures are midpoints of ranges published by Civils.ai: sand 10% and 5%, loam or topsoil 22.5% and 10%, clay 25% and 15%, and blasted rock 45% and 0%. They are typical, so check your geotechnical report, and a Florida DOT study found measured shrinkage well below the 30 to 35% the department had been assuming.
Rock is a special case. Blasted rock stays bulked after it is placed, so its compacted volume is not smaller than its bank volume, and the source gives a range of 0.95 to 1.05. The calculator therefore gives rock 0% shrinkage and never applies a negative one.
From volumes to lorries
Truck runs = ceil(loose volume / truck capacity), using loose cubic metres. The capacity of 8 m3 is an editable example, and your haulier states the real figure. The tool also shows the compacted volume of the dug soil, and the bank volume you would need to borrow to fill the same volume to a compacted state, with the loose volume to haul.
Earthworks are priced in the tendering and costing guide, tracked per job in projects and tenders, and plant and lorries can sit on the assets and documents register. Use the plant hourly cost calculator for machine rates, the crew size calculator for labour, and the S-curve calculator to spread the cost. A variation records a change in quantity. Related tools include the earned value calculator, the payment certificate calculator and the ready-mix concrete calculator.
Worked example
An excavation 20 m x 10 m x 3 m deep in clay, with vertical sides and an 8 m3 truck.
| Quantity | Working | Result |
|---|---|---|
| Bank volume | 20 x 10 x 3 | 600.00 m3 |
| Loose volume | 600 x 1.25 | 750.00 m3 |
| Truck runs | ceil(750 / 8) = ceil(93.75) | 94 |
| Compacted | 600 x 0.85 | 510.00 m3 |
| Bank soil to fill 600 m3 compacted | 600 / 0.85 | 705.88 m3 |
| Loose to haul for that | 705.88 x 1.25 | 882.35 m3 |
| Same hole, 1 : 0.5 side slopes | 600 + 0.5 x 9 x 30 + 4/3 x 0.25 x 27 | 744.00 m3 |
Worked example
An excavation of 20 m x 10 m x 3 m has a bank volume of 600 m3. In clay at 25% swell the loose volume is 600 x 1.25 = 750 m3, which is ceil(750 / 8) = 94 truck runs of 8 m3. At 15% shrinkage the dug soil would compact to 600 x 0.85 = 510 m3, and to fill 600 m3 compacted needs 600 / 0.85 = 705.88 m3 of bank soil, or 882.35 m3 loose. With 1 : 0.5 side slopes the same hole is 744 m3 bank.
Questions people ask
What are bank, loose and compacted volumes?
Soil in place, soil after excavation and soil after it is placed and compacted.
What is swell?
The increase in volume when soil is dug, measured from the bank volume.
What is shrinkage?
The reduction in volume when soil is compacted, measured from the bank volume.
Where do the swell and shrinkage figures come from?
They are midpoints of published ranges. They are typical, so check your geotechnical report and replace them.
How is rock treated?
Blasted rock stays bulked when placed, so rock is given 0% shrinkage here and shrinkage is never negative.
Can I enter my own swell?
Yes. Type any number, including 0. A blank box uses the typical figure for the soil.
How are truck runs counted?
Loose volume divided by truck capacity, rounded up. The 8 m3 capacity is an editable example.
What does the side slope field do?
It adds the extra volume of a cut with sloped sides, using the bottom length and width as the base.
Does it handle a trench or a basement?
Yes, with the length, width and depth of the cut. Irregular shapes need splitting into parts.
Does the result include the topsoil strip?
No. Strip topsoil as its own volume and add it.
Sources
- Civils.ai: Free Soil Bulking and Swell Factor Calculator (ranges by material)
- King Saud University: CE419 Construction Management, Chapter 2, Earthmoving Materials and Operations (swell, shrinkage, bank, loose and compacted)
- Chopra, University of Central Florida: Investigation of Shrink and Swell Factors for Soils Used in FDOT Construction (1999)