The Block CalculatorHow does this block wall calculator work?
A block wall is made of courses (horizontal rows). The number of courses is the wall height divided by the block height, and the number of blocks per course is the wall length divided by the block length. Multiplying the two gives the same answer as dividing areas, which is what the calculator does before rounding up.
Planning a block wall
- Design to block modules: if you set lengths and heights to multiples of the block size (for example 400 mm or 16″), you avoid most cutting and waste.
- Allow for a footing: the blocks sit on a concrete footing, which this calculator does not include.
- Double-leaf walls: for a cavity or double-thickness wall, multiply the result by the number of leaves.
Formula used
Total Blocks = (Wall Length × Wall Height) ÷ (Block Length × Block Height)The result is always rounded up to the next whole block, because you can’t buy part of one. Wall thickness is shown in the diagram but does not change the count for a single-wythe wall.
Example
Scenario: A wall 10 m long and 2 m high, built with blocks measuring 40 cm × 20 cm (0.4 m × 0.2 m).
Wall area: 10 m × 2 m = 20 m²
Block face area: 0.4 m × 0.2 m = 0.08 m²
Final result: 20 ÷ 0.08 = 250 blocks. Add 5–10% for cuts and breakage when you order.
Frequently asked questions
How do I calculate the number of courses?
Divide the wall height by the block height including the joint. A 2 m wall with 200 mm blocks has 10 courses.
How many blocks per course?
Divide the wall length by the block length including the joint. A 10 m wall with 400 mm blocks needs 25 blocks per course.
Last updated: . Results are estimates — see our disclaimer.