How this calculator works
Each block covers its own size plus one joint, so the blocks needed are the area, plus your cutting allowance, divided by the area of one block with its joint. For the standard 200 × 100 mm block with 3 mm joints that is about 48 per square metre. Under the blocks go a compacted sub-base of MOT Type 1 and a laying course of sand.
Worked example: a 6 × 5 m drive (30 m²) in 200 × 100 mm blocks with 3 mm joints and 5% for cuts: each block with its joint covers 0.203 × 0.103 = 0.0209 m², which is 47.8 blocks per m², so you need 30 × 1.05 × 47.8 = 1,507 blocks. A 150 mm sub-base takes 30 × 0.15 × 2.2 × 1.05 = 10.4 tonnes of MOT Type 1, and a 40 mm laying course 2.0 tonnes of sand.
Materials for common drive sizes (200 × 100 mm blocks, 3 mm joints, 5% waste)
150 mm sub-base and a 40 mm laying course.
| Drive size | Area | Blocks | MOT Type 1 | Laying sand |
|---|---|---|---|---|
| 3 × 5 m | 15 m² | 754 | 5.2 tonnes | 1.0 tonnes |
| 3 × 10 m | 30 m² | 1,507 | 10.4 tonnes | 2.0 tonnes |
| 5 × 5 m | 25 m² | 1,256 | 8.7 tonnes | 1.7 tonnes |
| 6 × 5 m | 30 m² | 1,507 | 10.4 tonnes | 2.0 tonnes |
| 6 × 8 m | 48 m² | 2,411 | 16.6 tonnes | 3.2 tonnes |
Tips before you buy
- Use blocks that are 60 mm thick for a drive that carries cars, and 80 mm where heavy vehicles go. 50 mm blocks are for patios and paths.
- Compact the MOT Type 1 in layers of about 100 mm with a plate compactor. A poor sub-base is the main reason block paving sinks and ruts.
- Screed the laying course to an even depth, and do not walk on it before the blocks go down. Compact the finished surface with a plate compactor fitted with a rubber pad, then sweep jointing sand into the gaps and compact again.
- Give a drive a fall of about 1 in 60 so water runs off, and in England remember that a paved front garden over 5 m² needs permeable paving or drainage to a lawn or border, otherwise it needs planning permission.
- Mix blocks from several packs as you lay, to blend any colour differences.
- Check for buried services before you dig, using the free LSBUD service.
Tools & materials for this project
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Frequently asked questions
How many block paving bricks per square metre?
About 48 for the standard 200 × 100 mm block with 3 mm joints, and around 50 if the blocks have no spacer gap. Add 5 to 10% for cuts.
How many blocks do I need for a 6m x 5m drive?
About 1,507 blocks of 200 × 100 mm with 5% for cuts. That is 30 m² at 47.8 blocks per m².
How deep should the sub-base be for block paving?
150 mm of compacted MOT Type 1 for a driveway, and 100 mm for a patio or path. On soft ground, go deeper.
What sand do I use under block paving?
A laying course of grit or sharp sand about 30 to 50 mm deep, screeded level. Do not use building sand, which holds water and will not drain.
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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.