Patio Calculator 2026
Instantly estimate the number of paving slabs, sub-base, and mortar needed for your DIY patio project. Calculate area, volume, and material wastage with precision.
Project Dimensions & Specs
Define your patio area and paving material parameters
Total dimensions of the paved area
Dimensions of a single paving slab
Spacing between slabs for pointing / jointing compound
Compacted MOT Type 1 or hardcore layer (typically 100-150mm)
Sand/cement mix or sharp sand layer beneath slabs
Extra materials for cuts, breakages, and complex patterns
Material Estimates
Slabs, sub-base, and mortar volumes
Enter your patio dimensions and slab specs above, then click Estimate Patio Materials to reveal your complete material list.
Common Slab Sizes & Coverage
Standard paving slab dimensions and their approximate coverage area without joints. Always add 10% for cuts and wastage.
| Slab Size (mm) | Area per Slab (m²) | Slabs per 10m² | Typical Use |
|---|---|---|---|
| 300 x 300 | 0.09 | 112 | Small pathways |
| 450 x 450 | 0.20 | 50 | Standard patios |
| 600 x 600 | 0.36 | 28 | Modern gardens |
| 600 x 900 | 0.54 | 19 | Large entertaining |
| 900 x 900 | 0.81 | 13 | Expansive landscapes |
Patio Building FAQ
Learn more about sub-base preparation, mortar mixing, and calculating paving materials for your DIY project.
To calculate the number of slabs, divide your total patio area by the area of a single slab (including the joint spacing). It is highly recommended to add 5-10% extra to account for cuts, breakages, and complex patterns.
A compacted sub-base (usually MOT Type 1) should be at least 100mm (4 inches) deep for standard foot traffic. If the patio will bear heavy loads or is built on soft, clay-heavy soil, increase the sub-base depth to 150mm (6 inches) to prevent sinking.
The bedding layer beneath the slabs typically requires a 30mm to 50mm depth of sharp sand or a semi-dry sand/cement mix. Multiply your patio area in square meters by the desired depth in meters to get the total cubic meters required.
Yes, always include a wastage allowance. For simple rectangular layouts, 5% is sufficient. For diagonal laying patterns, curved edges, or multiple cuts around obstacles, you should add 10% to 15% extra material to avoid running short mid-project.
For laying paving slabs, a classic mortar mix ratio of 4 parts sharp sand to 1 part cement is standard. For pointing the joints, a slightly softer mix of 3 parts sand to 1 part cement (or a specialized resin-based jointing compound) ensures durability and prevents cracking.