Block Paving Calculator
Calculate blocks, bedding sand and kiln dried jointing sand for any driveway or patio. Includes lay pattern wastage, sub-base estimate and 2026 UK pricing.
200×100mm standard: exactly 50 blocks per m². Joint gap of 3mm is factored in.
Stretcher bond: simple running bond, minimal cuts. Herringbone: 45° or 90°, more cuts but stronger interlock for driveways.
Area = π × (diameter ÷ 2)²
Use if you already know your total area.
MOT Type 1 at 2.1 t/m³ × 1.2 compaction
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Installation Guide
How to Lay Block Paving
The 50 Blocks Per m² Rule
Standard 200×100mm block paving gives exactly 50 blocks per m², regardless of the pattern used (herringbone, stretcher bond or basketweave). This is because the nominal 200×100mm dimension includes a 3mm joint on each face, giving an actual covered area of 203×103mm per block.
For other block sizes, the blocks/m² is calculated as: 1,000,000 ÷ ((block length + 3) × (block width + 3)). Always order at least 10% extra for herringbone patterns and edge cuts.
Lay Patterns & Wastage
Herringbone (45° or 90°) — BS 7533-102:2025 recommended for driveways: The strongest pattern for vehicle traffic. Blocks interlock at angles, distributing load across multiple blocks and preventing the "creep" that can occur under braking on slopes. 45° herringbone is preferred for inclines as it offers maximum resistance to longitudinal movement. Requires 10% wastage for the angled cuts at all edges.
Stretcher bond: Simple running bond, like brickwork. Fastest to lay and minimal waste (5%). Best for paths and patios not subject to vehicle loads.
Basketweave: Pairs of parallel blocks alternating in direction. Attractive but slightly more waste (8%) due to the pattern alignment requirements at borders.
Bedding Sand vs Kiln Dried Sand
Bedding sand (sharp sand, 30mm finished): Laid beneath the blocks before they are placed. Must be screeded to a precise level. Do not compact the bedding layer before laying — it compacts naturally when the blocks are vibrated in with a plate compactor. To achieve a finished 30mm bed, order for approximately 35–37mm of loose sand (allowing for ~15–20% compaction). Use sharp sand only, never building sand.
Kiln dried sand (jointing, 3.5kg/m²): Applied after all blocks are laid and the area is compacted. Sweep dry kiln dried sand across the surface with a stiff brush, then use the plate compactor again to vibrate it into the joints. Never use wet or damp sand for jointing — the joints will set hard and crack. Top up after the first flush of rain.
SuDS, Dropped Kerbs & Planning
Under the Sustainable Drainage (SuDS) provisions within Building Regulations Part H, any new driveway over 5 m² must manage surface water within the property. The simplest compliant solution is permeable block paving — blocks laid with wider joints filled with free-draining aggregate rather than kiln dried sand, allowing water to percolate through to a sub-base and into the ground below.
Standard non-permeable block paving is still permitted if surface water is directed to a soakaway or permeable area within your property boundary — not to the public highway or surface drain.
BS 7533-102:2025 governs the installation of pavements using modular paving units in the UK, superseding BS 7533-3:2005 (withdrawn) — the standard this calculator's block counts, joint widths and compaction factors are based on. Sub-base specifications follow SHW Clause 803 for MOT Type 1 unbound mixtures.
Dropped kerbs are always required to drive across a public footpath to access your property. You must apply to your local highway authority — installing one without permission is an offence and you will be required to reinstate the kerb at your own cost.
FAQ
Common Questions
Standard 200×100mm blocks give exactly 50 per m² (including the 3mm joint). 200×65mm patio blocks give approximately 77 per m². 150×150mm square blocks give approximately 44 per m². Always add 10% for herringbone patterns and edge cuts.
Herringbone (90°) is the strongest pattern for vehicle traffic and is recommended for all driveways. The interlocking angles distribute load across multiple blocks, preventing creep and rocking. Stretcher bond and basketweave are suitable for pedestrian areas but not for cars.
Kiln dried jointing sand is applied at approximately 3.5kg per m². For a 20m² driveway you need around 70kg — typically 3–4 bags of 20kg kiln dried sand. Apply dry, sweep into joints with a stiff brush after compaction, then compact again to vibrate it down. Top up after the first rain.
A pedestrian patio requires 75–100mm of compacted MOT Type 1 sub-base. A driveway for cars needs 150mm. Heavy vehicles require 200mm or more. The sub-base goes beneath a 30mm sharp sand bedding layer — so total excavation depth is typically 180–220mm for a domestic driveway.
Most domestic driveways are permitted development. You do not need planning permission if your driveway either uses permeable paving or drains to your own garden rather than the public highway. You always need council approval for a dropped kerb — you cannot install one without permission regardless of driveway size.