Concrete Block Calculator
How many concrete blocks do I need?
A standard UK concrete block is 440 by 215 mm, which with a 10 mm mortar joint gives 10 blocks per square metre. Enter the wall length and height and the calculator multiplies by 10 and adds 5% for cutting and breakages. Blocks cover ground far faster than bricks, which is why they are used for foundations, inner leaves and garden walls.
Measure the wall area and take off large openings. Allow mortar at roughly one 25 kg bag of cement plus soft sand for every square metre or so of blockwork, mixed around 1:5. Denser blocks are heavier to lift but stronger; lightweight aircrete blocks are easier to handle and cut.
Frequently asked questions
Is the concrete blocks calculator free?
Yes. It is completely free, with no sign-up and nothing to install. It runs entirely in your browser.
How accurate is it?
It gives a reliable estimate for ordering based on standard UK figures, but real quantities vary with ground conditions, wastage and how materials settle. Always add a margin and confirm with your supplier before buying.