Work out how many paving slabs and full packs to order for a rectangular or L-shaped patio. Use this calculator for a straight grid of rectangular slabs, all the same size.
Patio and paving slab calculator
Measure the finished paved area in metres. For an L-shaped patio, sketch it and split it into two rectangles that meet at the edge without overlapping. Enter each rectangle once. Use the supplier’s slab dimensions and planned joint width in millimetres.
How to use the estimate
The calculator counts rows and columns separately for each rectangle. Each slab position uses one slab, including positions that need a cut. It does not assume you can reuse offcuts across areas. Mark the joint lines on your sketch before ordering, especially where the two arms of an L meet. Rotating rectangular slabs may change the count, but the calculator keeps the chosen direction consistent across all areas.
The extra percentage is added to the slab count after sizing the grid. The default is 10%, which you can adjust. Full packs are rounded up, and the results show how many slabs those packs contain and how many are left above your target. For mixed-size patio packs, use the supplier’s laying pattern and stated coverage.
Worked example
For two non-overlapping areas of 3 m × 2 m and 2 m × 1 m, using 600 × 600 mm slabs with 10 mm joints, the first area needs 5 × 4 slab positions and the second needs 4 × 2. That gives 28 slabs before spares, or 31 with 10% extra. If your supplier sells packs of 12, order 3 full packs for 36 slabs.
Further Reading
