Site Cut Calculator
Compare your existing ground level to your finished floor level to work out whether your site needs a cut or imported fill, and by how much.
Site Cut Calculator
Compare existing ground level to finished floor level to size your site cut or fill.
Comparing Ground Level To Finished Floor Level
Before a slab goes down, the site needs to sit at the right level relative to your finished floor level (FFL). This calculator first works out your required site cut level as FFL − slab thickness, then compares that to your existing ground level (RL) to determine whether soil needs to be cut away or fill needs to be brought in, and by how much.
If your existing ground level is higher than the required cut level, the site needs excavation: the difference in levels multiplied by your project area gives the excavation volume, a 25 per cent bulking allowance is applied, and the total is converted into 10 m³ truck loads for disposal. If your existing ground level is lower, fill needs to be imported instead, calculated the same way but converted into 12 m³ truck loads (a typical size for importing clean fill).
What Information You Need To Enter
Enter your project area in square metres, your existing ground level (RL) and finished floor level (FFL) — both usually taken from a site survey or your building designer's drawings — and select your slab type, which determines the slab thickness used in the calculation.
Understanding Your Results
The calculator tells you clearly whether soil removal or imported fill is required (or neither, if your site already sits at the correct level), along with the required cut or fill depth in millimetres, the volume involved, and the number of truck loads needed.
Why Accurate Estimating Matters
Getting your cut and fill levels right before construction starts avoids a slab that sits too high or too low relative to existing ground, driveways or drainage falls — a mistake that is expensive and disruptive to correct once concrete is poured.
Frequently Asked Questions
What is RL and FFL?
RL (Reduced Level) refers to a ground level relative to a fixed survey datum, while FFL (Finished Floor Level) is the level your completed floor needs to sit at. Both are typically shown on a site survey or your building designer's drawings.
Why does slab type affect the required cut level?
Different slab types have different overall thicknesses -- a 385 mm waffle slab sits differently in the ground to a 110 mm raft slab -- so the ground preparation level needed to achieve the same finished floor level changes depending on which slab you are building.
What if my site needs both cut and fill in different areas?
This calculator gives you an average based on a single area and level difference. Larger or sloping sites often need a proper survey and cut/fill plan from your builder or surveyor to balance levels across the site.
Why is the truck size different for cut versus fill?
Removing spoil is typically done with a 10 m³ tandem tipper, while importing clean fill is commonly delivered in 12 m³ loads -- this reflects common practice for each type of haulage in Melbourne.
Does this calculator confirm my final site levels?
No -- it gives you a planning estimate. Final site levels should always be confirmed by a licensed surveyor, especially where drainage falls, easements or neighbouring properties are involved.
Related Calculators & Services
Need An Exact Price, Not Just An Estimate?
The Site Cut Calculator gives you a fast, useful planning figure. For a fixed, accurate price backed by a site assessment, request a free professional quotation from HPL Construction.
