Earthwork Volume API

Earthwork volume maths as an API, computed locally and deterministically — the cut/fill-quantity and soil-state numbers a civil engineer, estimator or grading contractor runs for a road, trench or site. The average-end-area endpoint gives the volume between two cross-sections = the mean of the two end areas × the distance between them, ÷ 27 for cubic yards — the everyday earthwork-quantity method you sum section by section down an alignment (a 100 ft²/150 ft² pair 100 ft apart is about 463 cy). The prismoidal endpoint gives the more accurate Simpson volume = length ÷ 6 × (A₁ + 4·A_mid + A₂) using the true middle-section area, preferred for payment quantities where the average-end-area over-estimate would matter. The soil-state endpoint converts between the three states earth passes through: loose = bank × (1 + swell %) (excavating loosens it, ~25 %, so you haul more cubic yards than you cut) and compacted = bank × (1 − shrinkage %) (placing and compacting shrinks it, ~10 %) — which is why a balanced cut-and-fill needs more bank cut than the compacted fill, with the load factor for truck sizing. Everything is computed locally and deterministically, so it is instant and private. Ideal for grading and site-work estimating, surveying and civil-design tools, and earthmoving calculators. Pure local computation — no key, no third-party service, instant. US units (ft², ft, cy). 3 compute endpoints. For tank/storage volumes use a tank API; for concrete mix a concrete API.