FIELD CALCULATOR / FEET AND CUBIC YARDS
Bank yards, loose yards, tons.
Dimensions in feet, answers in the units you actually order and haul by. The swell factor and density are yours to set, and they are shown with the result rather than hidden inside it.
Enter the dimensions above.
You will get bank volume, loose volume, estimated weight and a volume-based load count.
How it works
- Bank cubic yards = length × width × depth ÷ 27. This is the material as it sits in the ground, undisturbed.
- Loose cubic yards = bank × swell factor. Digging bulks material up; this is what you actually have to haul.
- Short tons = loose yd³ × loose density. One short ton is 2,000 lb.
- Loads = loose yd³ ÷ truck capacity, rounded up.
Bank, loose and compacted are three different numbers
This is where quantities go wrong, and it is worth being pedantic about:
Bank is the in-place volume — what you measure off the drawings and what you are usually paid for. Loose is the same material after it has been dug, bulked up by its swell factor, and it is what fills trucks. Compacted is the same material placed and rolled, and it takes up less room than it did in the ground.
So a cubic yard dug out does not backfill a cubic yard of hole, and the truck count never comes off the bank figure. Order fill by compacted volume, haul spoil by loose volume, and get paid by bank volume.
90 ft long, 12 ft wide, 1 ft deep: 90 × 12 × 1 = 1,080 cubic feet. Divide by 27 and that is 40 bank yd³.
At a swell factor of 1.15 it comes out as 40 × 1.15 = 46 loose yd³.
At 1.35 tons per loose yard that is 46 × 1.35 = 62.1 short tons.
In 12-yard trucks: 46 ÷ 12 = 3.83, so 4 loads by volume — though at 62.1 tons across 4 loads you would be asking each truck to carry 15.5 tons, which may be over the legal payload. Check the weight limit too.
Typical material factors
The presets above load these published starting values. They are a reasonable place to begin and a poor place to finish — real material varies with moisture, compaction and how it was dug.
| Material | Swell | Shrink | Loose density (tons/yd³) |
|---|---|---|---|
| Common earth | 1.15 | 0.90 | 1.35 |
| Clay | 1.25 | 0.85 | 1.45 |
| Sand | 1.10 | 0.95 | 1.30 |
| Gravel | 1.12 | 0.92 | 1.50 |
| Rock | 1.50 | 0.75 | 1.70 |
Swell above 1 expands the volume when you dig it; shrink below 1 reduces it when you compact it. Rock swells half as much again and is the material most likely to make a volume-only truck count wrong.
What this shape assumes
This calculates a rectangular prism: vertical sides, flat bottom, constant depth. That is a fair model for a boxed or shored trench and for a uniform pad.
It is not the right model for a sloped or benched excavation, where the top is wider than the bottom and the extra material can be a large fraction of the total. For a trapezoidal section, average the top and bottom widths before entering a width, and treat the answer as an approximation.
It also does not subtract the pipe, structure or bedding that will occupy part of the trench, and it does not handle changing depth along a run. For a trench that gets deeper as it goes, break it into segments of roughly constant depth and add them up.
Before you rely on the number
Check that depth is measured from existing grade rather than from finished grade, that width is the excavated width rather than the pipe width, and that your swell factor matches the material you are actually in and not the material the drawings assumed. An estimate carrying the wrong swell is wrong by exactly that percentage, every time, and it will not look wrong.
Keep it with the job
The Driftless Field workspace saves the estimate against a named job and prints the assumptions on the report — swell, density and truck capacity all shown, so the figure can be checked later instead of taken on trust.
Related: truck load calculator · grade check calculator