Paving Calculator

Paving Calculator estimates exactly how many paving slabs you need, plus MOT Type 1 sub-base aggregate, laying-bed sharp sand, and bagged cement for pointing — built for UK landscapers, patio fitters, and serious DIYers.

Enter your patio length and width, pick a UK paving-slab size, set your joint width, sub-base depth and waste percentage, then hit Calculate. The app returns slab count, sub-base tonnage, laying-bed sand tonnage, pointing sand tonnage and cement-bag count, plus a per-line cost breakdown if you supply prices.

KEY FEATURES

• Five standard UK slab presets — 300×300, 450×450, 600×300, 600×600 (the trade default), and 900×600 heavy-duty
• MOT Type 1 sub-base aggregate calculation at 2.1 t/m³ (Mainland Aggregates / Smith & Sons range)
• Laying-bed sharp sand quantity calculation at 1.6 t/m³ loose density
• BS 7533-aligned pointing mortar — 3:1 sharp sand : Portland cement (pavingexpert / pavingshopper UK trade standard)
• Pointing depth capped at 25mm (typical UK weather-proofing depth — not the full slab thickness)
• Configurable joint width (5, 8, 10, 12, 15mm) and sub-base depth (50-300mm)
• Adjustable waste percentage (0-25%) — default 10% for straight layouts, raise to 15% for diagonal/herringbone
• Optional cost estimation per material — slabs, MOT, sand, cement
• Share results to text, email or messaging apps
• Standard sub-base hint: 100mm for patios, 150mm for driveways

CALCULATION ACCURACY

Constants and rules cross-referenced with BS 7533 (UK modular paving), Mainland Aggregates and Smith & Sons Bletchington (MOT Type 1 density), Marshalls and Bradstone supplier catalogues (slab dimensions and thicknesses), and pavingexpert.com / pavingshopper.co.uk (3:1 pointing mortar convention). Each density and ratio constant is cited inline in the source code for auditability.

WHO IT'S FOR

• Landscapers and patio fitters quoting jobs
• Homeowners planning a new patio or garden path
• DIYers replacing damaged paving runs