Patio & Paving Calculator
Calculate paving slabs, waste allowance, sub-base and bedding quantities for a rectangular patio or paved area.
Typical use: Paving slabs, porcelain & sandstone paving, granular sub-base, bedding layer volume
Using this calculator
Open the interactive calculator to enter your project measurements and adjust the available settings. Review the calculated quantity and buying units before ordering materials. Check product coverage, pack sizes and installation guidance with the manufacturer or supplier.
Planning and practical guidance
How to Plan & Lay a Patio: Sub-Base, Falls, Bedding & Joints
Understand the build-up beneath paving, why drainage falls matter and how paving type changes the bedding and jointing system.
- Set out the finished patio footprint and confirm finished levels before excavating. Pay particular attention to doors, thresholds, drainage, air bricks and the building damp-proof course.
- Plan a positive fall so surface water drains to an appropriate location rather than toward the building. The exact fall depends on the paving and drainage design; heavily textured surfaces can need more fall than smooth paving.
- Excavate soft or unsuitable material and create a stable formation. Ground conditions and intended loading determine how much build-up is required.
- Lay and compact a suitable sub-base where required, in layers if necessary, and form the drainage fall in the sub-base rather than trying to create it by making one side of the mortar bed unusually thick.