Paving Slab Calculator
Estimate single-size slabs or whole paving packs from the real paved area, using the product dimensions or manufacturer coverage you actually intend to buy.
Choose the quantity method that matches the product
For a real order, use the manufacturer or supplier’s stated pack coverage when you have it. Use single-size slab dimensions when you need a theoretical piece count for one repeated slab size.
Why pack coverage is usually the safest buying input
UK paving is sold in many formats. Current manufacturer ranges include single-size packs and mixed-size project packs with their own stated square-metre coverage. A project pack cannot be reduced accurately to one repeated slab dimension, so the calculator treats published pack coverage as the preferred purchasing conversion whenever it is available.
Use the actual surface footprint. Split irregular shapes into measurable sections and add them together.
Enter manufacturer pack coverage, or the real face dimensions for one repeated slab size.
The calculator starts at 0%. Cuts, borders, patterns and breakage vary, so the extra allowance stays visible and editable.
Single-size mode: theoretical slabs = paved area ÷ slab face area. Final purchase quantity = round up after applying the user-selected extra allowance.
Worked examples
Pack coverage: if the exact product states 7.92 m² per pack, a 15.84 m² area needs exactly 2.00 theoretical packs and therefore 2 whole packs at the default 0% extra.
Single-size slab: a 600 × 600 mm slab has a face area of 0.36 m². A 7.20 m² surface is 20.00 theoretical slabs before any user-selected cutting or breakage allowance.
Why the calculator does not assume one joint width
Joint recommendations differ with paving material and product system. Current Marshalls guidance distinguishes typical concrete-paving joints from narrower porcelain joints, and Bradstone product ranges also publish different joint widths by product. Rather than impose one gap on every patio, this calculator leaves joint design to the chosen paving specification and recommends the product’s stated pack coverage for ordering.
Marshalls Heritage paving · Marshalls SYMPHONY Classic packs · Marshalls paving technical information · Bradstone paving range / joint widths · Wickes 600 × 600 pack example
What this result does—and does not—tell you
- Mixed-size packs: use the manufacturer’s pack coverage, not one average slab size.
- Irregular or curved areas: measure the real footprint carefully; edge cuts may change the practical order.
- Diagonal layouts, borders and patterns: these can create more offcuts, so choose an extra allowance deliberately.
- Single-size slab mode: the result is an area-based piece estimate, not a row-by-row cutting layout.
- Sub-base and bedding: calculate these separately from area and specified depth; this tool does not infer them from slab count.
Planning estimate only. Confirm the final order against the exact manufacturer data, pack composition, laying pattern and supplier sales unit. This calculator does not design the sub-base, bedding, drainage or installation specification.
Continue the patio estimating workflow
Frequently asked questions
Should I use slab dimensions or pack coverage?
Use the exact manufacturer or supplier pack coverage when it is available, especially for mixed-size project packs. Use slab dimensions for a theoretical single-size piece count.
Does the calculator assume a paving joint width?
No. Joint widths vary by material and system. Use the chosen product’s installation guidance, and prefer its published pack coverage for purchasing where available.
Does it automatically add 10% waste?
No. The extra allowance starts at 0% and stays visible so you can choose a value that reflects the actual cutting pattern and breakage risk.