The grid method in one paragraph
Shoot elevations on a regular grid across the site. At every grid point subtract the proposed elevation from the existing one, which gives a depth of cut where the number is positive and a depth of fill where it is negative. Each square between four points is a cell. Average the four corner depths, multiply by the cell area, and you have the volume for that cell. Add the positive cells together to get total cut and the negative cells together to get total fill. That is the whole method, and it has been done on graph paper for a century.
Its accuracy is entirely a function of grid spacing against how broken the ground is. On a smooth field a 50 foot grid is plenty. On rolling ground or across an existing swale, a 50 foot grid can miss a whole landform between shots. If tightening the grid changes the answer much, the answer was not converged and the tighter one is closer to true.
Why the two numbers must not be netted
Suppose a site cuts 800 yards and fills 780. The net is 20 yards, which reads like almost nothing needs to happen. In reality a machine lifts, carries and places 1,580 yards of material, and the cost of the job tracks that figure, not the balance. Netting also hides distance: cut in the far corner and fill at the entrance is a very different job from cut and fill sitting side by side, and no volume calculation of any kind will show you that. Look at where the daylight line falls on your grid, not just at the totals.
The second reason to keep them apart is that they are measured in different states. Cut is bank material, sitting undisturbed. Fill is compacted material, already placed and rolled. Converting between them needs the shrink factor, and until you apply it you are subtracting two quantities that are not in the same units. This calculator converts the fill to the bank volume required to build it before it compares anything.
Reading the balance honestly
| What the result says | What it means on the ground |
|---|---|
| Surplus | More material comes out than the fill can absorb. It goes on trucks in loose measure, so apply swell before counting loads, and it needs somewhere legal to go. |
| Short | Fill exceeds usable cut. Imported material is bought loose and delivered loose, and it compacts down, so order against the loose figure and expect the in-place result to be smaller. |
| Balanced | The trucking line is small. The machine line is not. Balance says nothing about how far the material travels or how many times it is rehandled. |
One correction people forget: not all cut is usable fill. Topsoil, organics, soft or wet clay and anything with debris in it generally cannot go under a structure or a pavement, so a site can show a healthy surplus and still need imported structural fill. Set the stripping depth here and that volume is reported on its own rather than counted as material available to build with.
What a grid cannot tell you
This produces quantities, and quantities are only one input to a grading design. Whether the proposed surface drains where it should, whether it puts water on a neighbour, whether the slopes are stable, whether the fill can be compacted to a specification and who inspects that — none of it is here. Drainage in particular is where amateur grading causes expensive trouble, because a pad that balances beautifully can still send every storm at a foundation. Check the fall you intend with the slope and grade calculator before you commit to a pad elevation, and once the quantities settle, the excavation volume calculator handles trucking for the surplus and the erosion and sediment control calculator covers what has to be in the ground before the first cut.
Questions people ask
How tight does the grid need to be?
Tight enough that the answer stops changing. The practical test is to run it at your spacing, then run a portion at half the spacing, and see whether the volume moves much. On flat, uniform ground a wide grid converges quickly. Across a swale, a bank, or ground with ledge outcrops, a wide grid can be badly wrong because the method assumes the surface between four shots is a plane. Also add shots at breaks in slope rather than only on the regular grid — a grid that ignores the top and toe of an existing bank will miss the landform entirely no matter how many points it has.
Why does the fill need more bank material than its own volume?
Because compacted fill is denser than the same soil was sitting in the ground. Placing material in lifts and rolling it drives out voids that the undisturbed soil had, so a cubic yard of bank material becomes somewhat less than a cubic yard once it is compacted into a fill. That reduction is the shrink factor. To build 780 compacted yards at 12 percent shrink you need about 886 bank yards of material, which is why a site that looks balanced on raw cut and fill can still come up short. The factor depends on the material and its moisture, so it is an input here.
Can I use this for a driveway or a trench instead of a pad?
A grid works badly for long linear work. Roads, driveways and trenches are conventionally computed by average end area: take cross sections at stations along the run, average the cut area of each adjacent pair, and multiply by the distance between them. That handles a narrow corridor far better than a square grid, which either has too few columns across the width or an absurd number of points along the length. For a simple prismatic trench or pit with roughly constant dimensions the excavation volume calculator is the direct route.
What if some cells are partly cut and partly fill?
The method averages the four corners, so within such a cell a little cut cancels a little fill and both disappear from the totals. The result is that cut and fill are each slightly understated wherever the daylight line — the boundary where existing and proposed elevations meet — passes through a cell rather than along its edge. The calculator counts those cells and tells you how many there are. If the daylight line meanders across a lot of your grid, tighten the spacing along it, which is where the extra shots earn their keep.
Do I need a permit to regrade my own property?
That is a local question and this calculator will not answer it, because the answer varies by jurisdiction and sometimes by parcel. Grading plans, disturbed-area thresholds, stormwater permits, erosion control requirements, setbacks from property lines and restrictions near wetlands, floodplains or watercourses are all set locally, and some of them are federal. Regrading can also change where water goes, which creates liability toward neighbouring properties independent of any permit. Call your local building department and stormwater or conservation authority before the machine arrives, not after a neighbour does.