Check the path
Your calculation audit
Every total is shown as a short sequence so you can see what was measured, deducted, adjusted and rounded.
- 01Awaiting valid measurementsComplete the fields above to reveal the formula path.
Paving & Decking
Paving calculator
Estimate paving slabs or pavers for a patio or path, with joint gap, waste and pack rounding.
Transparent formulaFormula v1.0 · finished area ÷ paving-unit footprint × waste allowance
Scope boundary: Surface-material estimate only — it does not assess drainage, sub-base, ground preparation or compliance.
Measure clearly
Simple guidance
Measure the finished patio or path area. Use the actual paving-unit dimensions and include a joint gap only when you want that spacing included in the unit footprint.
Worked example
Follow the same logic
A 12 m² patio using 600 × 600 mm slabs needs about 33.3 units before the selected cut allowance and pack rounding when the joint gap is set to zero.
Planning tipWrite down the product factor or pack size you used, so a later change is easy to trace.
Before you buy
Three quick checks
- 01
Measure the finished surface, excluding areas that will not be paved.
- 02
Use actual slab or paver dimensions, not a nominal product name.
- 03
Confirm pack contents, cuts and colour/finish before ordering.
Quick answers
Useful to know
Should I add a joint gap?
Add the installed joint gap if you want it included in the paving-unit footprint. Set it to zero to calculate from the unit face area only.
Does this calculate drainage or sub-base?
No. It estimates surface paving units only and does not assess drainage, sub-base, ground preparation or compliance.
Review record
Transparent, source-ready method
Last reviewed: 15 October 2026. Formula version: v1.0. Source/review data to be added — Calculator.Shop does not present placeholder figures as an authoritative trade specification.