Excavation Calculator
Dig the pit in bank yards, haul it in loose ones: the swell factor that turns a neat rectangle into the truckloads leaving the site.
Excavation Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Vertical-sided rectangles — no batter or slope volume.
- Swell bands are planning values; the soil decides.
- No groundwater, shoring or over-dig modelling.
In short: The spine pit — 20 × 24 ft, 8 in deep — is 11.851852 bank yd³, exactly the slab's net plus the base's in-place volume. Swell it 20% and 14.222222 loose yd³ leave the site: 1.42 loads, so two trucks.
Formula
bank yd³ = ft² × depth ÷ 324
loose yd³ = bank × (1 + swell)
loads = loose ÷ truck capacity, rounded up
[('bank', 'in-ground measure — the drawing'), ('swell', "the bucket's inflation, 15-25% earth"), ('loads', 'loose ÷ truck, always rounded up'), ('refill', 'bank measure back, compacted below')]
Worked Example
- Multiply the rectangle into bank yards.
- Name the pit's appetite against the slab and base pages.
- Swell the bank into loose yards for haulage.
- Divide by the truck and round up to whole loads.
- Show the refill side in bank measure for the fill pages.
20 × 24 ft at 8 in: 11.851852 bank yd³ (the slab's 5.9259 + the base's 5.9259), swelling 20% to 14.222222 loose yd³ — 1.42 loads, two 10-yd trucks. Refilled, the pit wants its 11.851852 bank yards back.
Strengths & Limits Of This Model
Where this engine is strong
- Bank and loose kept in separate, labelled columns
- Pit reconciled to the fill and pour pages exactly
- Load round-up mirrors how haulers actually book
Where it stops
- No sloped-side volume
- Two-material digs must be summed
Practical Use Cases
Slab & base digs
The pit before the pour.
Haul-off quotes
Loose yards against truck minimums.
Spoil planning
Where the piles stand and grow.
Pool & pond digs
Deep bank measures, big swell.
Backfill orders
Refill in bank, compact below.
Methodology & Editorial Standards
Bank volume is the rectangle × depth ÷ 324; loose volume multiplies the swell factor and haulage divides by truck capacity with a round-up, because part-loads still book trucks. The pit's appetite is reconciled against the slab and base pages' volumes — one rectangle wearing three hats — and refill is stated in bank measure. Zero dimensions or sub-yard trucks are refused.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Excavation Calculator — 10 Expert FAQs
10 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How do I calculate excavation volume?
Length × width × depth in feet, divided by 27 — bank yards in the ground. The spine pit: 480 ft² × 8 in is 11.852 bank yards before anything swells.
What is the swell factor?
The volume increase when ground is dug: loose earth runs 15-25% over bank, rock more, damp clay towards the top of the band. It is why 12 bank yards of pit will not fit back in 12 bank yards of trucks.
Bank yards or loose yards — which do I order?
Haulage prices LOOSE — the truck carries fluffed spoil. Fill and backfill are bank-measure plans, because engineered fill compacts below bank. Every mistake is one measure quoted as the other.
How many truckloads is my excavation?
Loose yards divided by truck capacity, rounded up — the worked pit is 14.22 loose yards, so two 10-yard trucks though the second leaves half-empty.
Does the spoil pile fit on site?
Loose spoil spreads roughly a third wider than the hole it came from and needs standing room besides. Plan the pile's footprint before digging, or budget the dump runs from day one.
Why is my dig bigger than the drawing?
Buckets over-cut, walls slump and sheeting eats space real projects pay for. The page prices the neat rectangle; the site's honesty rides in the swell factor and the margin you add.
What about groundwater?
Water is volume the truck cannot carry and the pump must — dewatering is its own line item, priced by the site, not by this page. Note it before the dig, not during.
Does backfill compact to the dug volume?
Below it — engineered fill is compacted in lifts to denser-than-loose, often denser than bank. That gap is why the fill pages carry compaction allowances and this page hands the pit back in bank measure.
How deep before I need shoring?
A protective-system question owned by your safety authority — depth bands, soil class and spoil setback all govern. This page will not guess; dig safe arithmetic starts where this page ends.
Rock changes what?
Swell jumps, production drops, and the truck count climbs the swell table — 25% is the chip's top band but solid rock can run further. Price rock as a different material, because it is one.