How this calculation works
Interpolate existing and design elevations on the same two triangles per cell. Clip their linear height difference at zero before integrating cut and fill, so mixed regions do not cancel into an incorrect zero. The chosen diagonal is part of the surface model.
Height difference = existing − design; integrate positive and negative regions on each chosen planar triangleA worked example
A 5 × 5 m cell with all existing elevations 101 m and target 100 m has 25 m³ cut and no fill. A mixed-sign cell needs separate positive/negative integration; averaging its four corners can hide both quantities.
Good to know
At most 10 × 10 cells, uniform horizontal spacing, a common unit/reference and explicitly chosen planar interpolation. This describes supplied nodes, not unmeasured terrain. Diagonal choice can change the volume. No shrink/swell, suitability of cut material for fill, haul, topsoil stripping, survey accuracy or earthworks specification is inferred.
Reference: FHWA: geometric earthwork representation and material-state context (opens in a new tab) ↗
Check the land-unit definitions and sources
The standard factors use the international foot and an acre of 43,560 sq ft. Cent means 1/100 acre; gunta means 1/40 acre; the selected Chennai ground means 2,400 sq ft.
The Assam report defines bigha as 14,400 sq ft, katha as 2,880 sq ft and lecha as 144 sq ft. The cited West Bengal court order mentions a 720-sq-ft katha convention. These are explicit presets, not an automatic definition for every record or every place using the same name. Match your record to the stated convention, or use its verified custom factor.
- NIST: exact international-foot and acre factors (opens in a new tab) ↗
- API Setu MDDS: acre/cent and acre/gunta relationships (opens in a new tab) ↗
- Greater Chennai Corporation: one ground is 2,400 sq ft (opens in a new tab) ↗
- Government of Assam AIRBMP framework: section 7.2, page 28 (bigha, katha and lecha) (opens in a new tab) ↗
- Supreme Court order, 7 May 2025: paragraph 2, page 2 (West Bengal katha) (opens in a new tab) ↗
The acre relationships are converted using exact base factors. Rounded or unrelated regional values in a reference table are not substituted for these definitions.
Mixed cut and fill require separate regions
Existing minus design elevation is positive where the model requires cut and negative where it requires fill. A zero average of mixed corner values does not mean every part of the cell is already at design level.
For a 5 × 5 m cell with height differences +1, −1 on the first row and −1, +1 on the second, the selected top-left to bottom-right diagonal gives cut 125/12 m³ and fill 25/12 m³. Both quantities are positive, even though the unweighted average of the four corners is zero.
The tool splits a cell into two stated planar triangles. On each triangle it clips the linear height difference at zero, then integrates each region using its area and vertex heights. No positive and negative volumes are cancelled before their individual totals are retained.
The diagonal is part of the surface assumption
Switching the diagonal in that mixed example reverses which high or low nodes are connected. The cut and fill totals then swap. The four measured nodes alone do not determine all the terrain between them, so choosing an interpolation method is a real modeling decision.
A matching design grid allows a varying target; flat-target mode supplies one target elevation at every node. Both surfaces use the same cell triangles and common unit/reference. Column and row spacing are horizontal, not distances along slopes.
The land elevation profile is useful for inspecting a one-dimensional measured section. This grid adds a two-dimensional surface model, but neither one certifies unmeasured terrain. Soil delivery loads also require separate material-state factors; geometric cut minus fill is not automatically a haul surplus or suitable fill supply.
A few questions, answered
Why not average four corner differences and multiply by cell area?
That shortcut can hide simultaneous cut and fill. This tool keeps both regions and explicitly chooses triangular interpolation.
Are the row names compass directions?
No. Top-left and bottom-right describe the input table’s order. No map orientation, coordinate datum or location is assigned.
Can cut volume directly replace the fill volume?
No material suitability or bank/loose/compacted conversion is determined. These are geometric surface-difference quantities only.