Patio Paving Calculator
Calculate paving slabs needed for your patio or path. Includes jointing sand estimate.
Last updated: April 2026 · Source: GOV.UK — Building Regulations Approved Document H
Slabs Needed
34
Area
12.0 m²
Jointing Sand
60 kg
Slab Cost
£119.00
Disclaimer
This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.
How It Works
Paving calculations divide the total area by the area of a single slab or paver block. Common UK paving slab sizes include 450 × 450 mm (approx. 5 per m²), 600 × 600 mm (approx. 2.8 per m²) and 600 × 300 mm (approx. 5.6 per m²). Block paving (200 × 100 mm) requires approximately 50 blocks per m².
Allow a 10 mm joint between slabs (reduces coverage slightly) and add 5–10% extra for cuts and breakage. The calculator also estimates sub-base material: a 100–150 mm compacted Type 1 sub-base is standard for patios, while driveways need 150–200 mm. A 25–40 mm mortar or sand bed sits on top.
Enter the area dimensions, slab size and joint width. The calculator shows slabs needed, sand or mortar quantity, sub-base material in tonnes and estimated cost. For driveways over 5 m² of impermeable paving, planning permission may be required unless you use permeable paving or drain to a lawn or border.
Example: Patio 4 m × 3 m, 600 × 600 mm slabs, 10 mm joints
- Area: 12 m²
- Slabs per m² (with joints): 2.7
- Total slabs: 12 × 2.7 = 32.4, round up to 33 + 5% = 35 slabs
- Sub-base (Type 1, 100 mm depth): 12 × 0.1 × 2.1 t/m³ ≈ 2.5 tonnes
- Mortar bed (30 mm): ~10 bags of sand-cement mix
Frequently Asked Questions
- What does the Patio Paving Calculator do?
- Calculate paving slabs needed for your patio or path. Includes jointing sand estimate. All calculations are performed in your browser using official UK rates and thresholds.
- Does this include delivery costs?
- This calculator estimates material quantities and approximate costs. Delivery charges vary by supplier, quantity and location. Bulk orders often qualify for free or reduced delivery.
- When is the best time for this project?
- Timing depends on the specific project. Generally, spring and autumn are ideal for lawn and planting work, while hard landscaping can be done year-round in dry conditions.