Concrete Block Calculator - How Many Blocks You Need (UK)
Work out how many concrete blocks you need for a wall using the UK standard 440 × 215mm block - dense or aerated (thermal) - with wastage included.
Interested? Then → Quotato for Builders · More advice on the Blog & Chips guides.
How to use this calculator
Measure the wall length and height in metres. Choose dense blocks for strength and below-ground work, or aerated (thermal) blocks for insulation in cavity walls.
How we calculate this
- Blocks needed = wall area × blocks per m² × (1 + wastage).
- A standard 440 × 215mm block face (with a 10mm joint) gives about 10.6 blocks per m².
- We add 5% wastage for cuts and breakages.
Worked example
A 5m × 1.8m wall is 9 m². 9 × 10.6 ≈ 95 blocks, plus 5% wastage ≈ 100 blocks. Add mortar from the mortar calculator.
UK notes & gotchas
- Standard block is 440 × 215mm; thickness (100mm most common) affects strength and price, not the per-m² count.
- Aerated/thermal blocks are lighter and insulate better; dense blocks are stronger and used below DPC.
- Check block strength (N/mm²) for load-bearing work - ask a builder or structural engineer if unsure.
FAQ
How many concrete blocks per square metre?
About 10 (10.6 to be exact) for a standard 440 × 215mm block laid with a 10mm joint.
Dense or aerated blocks - which do I need?
Dense for strength and below-ground work; aerated (thermal) for insulation in cavity walls. Many builds use both in different places.
How much wastage for blockwork?
5% is fine for a plain wall; add more for lots of cuts, piers or returns.
Related calculators
brick calculator · mortar calculator · concrete slab calculator