Block Calculator
Calculate the number of concrete or AAC blocks and mortar volume needed for a wall.
- Free to use
- Accurate results
- No registration required
- Works on all devices
Enter your wall dimensions and block size to find how many blocks and how much mortar you need.
Your result
105
Blocks needed
Mortar volume0.12
AI explanation
Formula
Wall volume ÷ (block volume + mortar joint on each side), rounded up, plus a wastage allowanceWorked example
3m × 3m wall, 200mm thick, 400×200×200mm blocks, 10mm joints, 5% wastage
| Field | Value |
|---|---|
| Wall length (m) | 3 |
| Wall height (m) | 3 |
| Wall thickness (m) | 0.2 |
| Block length (mm) | 400 |
| Block width (mm) | 200 |
| Block height (mm) | 200 |
| Mortar joint thickness (mm) | 10 |
| Wastage allowance (%) | 5 |
| Blocks needed | 105 |
| Mortar volume | 0.12 |
Assumptions
- Defaults to a common 400×200×200mm concrete/AAC block size, but any block size can be entered to match your specific product.
Frequently asked questions
How is block construction different from brick construction?
Blocks (concrete or AAC) are larger than standard bricks, so far fewer units are needed per wall — often making construction faster, though brick and block have different strength and thermal properties.
What block size should I use?
400×200×200mm is a common size, but check your specific product's dimensions and enter them here for an accurate count.
Is there a version of this for standard clay bricks?
Yes — see the Brick Calculator, which uses the same calculation with standard brick dimensions as the default.