Getting a useful estimate
Use rectangular slab dimensions and the planned joint width. Mixed-size packs and individual cuts need a separate layout.
Measure the space you need to fill. Rectangles use length and width; circles use diameter. For several sections, choose combined areas and add rectangles, then subtract exclusions. The final area must be greater than zero.
Count rectangular slabs and full packs
Enter patio dimensions in metres and slab dimensions and joint width in millimetres. The calculator treats each slab and its joint as a rectangular module, then applies your cutting allowance and rounds up.
This is an area estimate, not a cutting layout. Edge joints, borders and cuts can change the exact count. For mixed-size packs, use the supplier’s coverage per pack; this tool does not model a laying pattern.
Choose the bedding system for the slab
Marshalls distinguishes rigid mortar bedding from flexible sand bedding. Its guidance also requires joints between flags. Use the product installation instructions to set the joint and bedding specification.
This tool counts slabs and packs only. Calculate Type 1 separately; the sharp-sand tool estimates a sand layer and does not estimate mortar ingredients.
Check packs, cuts and delivery
If the supplier quotes pack coverage, enter it in m². Full packs round up independently of the estimated slab count. Check whether that coverage includes joints and compare it with the planned layout.
Confirm delivery access, unloading and the total price including VAT. The result does not include borders, jointing compound, installation labour or breakages beyond your entered allowance.
Slab and pack formulas
Slab counts round up to whole pieces. Packs = area × (1 + cutting allowance ÷ 100) ÷ supplier pack coverage, rounded up. Dimensions are converted to metres before calculation.
Sources & what they cover
- NIST SI conversion factorsNational Institute of Standards and Technology
Exact US customary and SI conversion factors; no material or installation recommendations.
Source checked - Paving installation and delivery FAQsMarshalls
Different bedding systems for paving flags, joints, VAT and delivery access. No generic installation specification imported.
Source checked
We check what each reference covers. A source check does not mean a specialist has reviewed this tool. You supply the depths, densities, prices and blend proportions.