Brick and Block Calculator
Work out how many bricks or blocks your walls need: count per square foot (or m²) including mortar joints, total for the walls net of windows and doors, how many to buy with a waste allowance, and how much mortar. Works in feet and inches or metric. It counts material for the wall you choose; it does not check whether that wall is strong or warm enough.
Units
Walls and openings
Brick or block
Allowances
Before you order
- This calculator counts material for the wall you pick. It does NOT check whether a single-wythe veneer, a solid brick wall or a block wall can carry your floors and roof or meets energy rules — that is for a designer working to your local building code. Interior walls of a different thickness should be run as a separate calculation.
- Joints matter. With a 3/8 in joint a US modular brick lays 6.86 per sq ft; when modular brick is laid to an 8 in module for 3 courses the bed joint is wider and the Brick Industry Association counts 6.75. In metric, a 10 mm joint is the usual default; some codes specify a 12 mm bed joint, which gives about 2.5% fewer bricks. Thin-joint aircrete blocks go on adhesive with joints of about 2 mm.
- Mortar is shown twice: the theoretical volume in the joints, and that volume plus a loss allowance (20% by default; the Brick Industry Association suggests 15–25%). Frogged or cored bricks and rough work take more. Convert to bags using the yield printed on your mortar.
- Add at least 5% to bricks for breakage and cutting, more for many corners, piers or bonds with header courses. Measuring the building on the outside already gives a small extra at the corners.
How this is calculated
The calculator follows the wall-area method used by the Brick Industry Association and the concrete masonry industry. The wall area is the perimeter of the building (twice length plus width) times the wall height, minus all windows and doors. Each brick or block, together with one bed joint and one head joint, covers (length + joint) × (height + joint) of wall face; one divided by that is the number per square foot or square metre for one wythe, and a wall two or more units thick needs that many times more. The net count is increased by your waste allowance and rounded up. Mortar is the wall volume (net area × thickness) minus the volume of the units — the theoretical amount in the joints — and then a loss allowance is added on top. Imperial inputs are converted with exact foot and inch definitions, so both unit systems give the same result for the same wall.
Common questions
Why don't I get exactly 7 bricks per square foot (or 60 per m²)?
Those are rounded rules of thumb for one particular brick and joint. A US modular brick with 3/8 in joints works out to 6.86 per sq ft; a UK standard brick with 10 mm joints works out to 59.3 per m², which suppliers round to 60. Change the brick, the joint or the wall thickness and the number changes — enter your actual brick and joint to get your figure.
Can I use it for concrete or aircrete blocks?
Yes. Enter the block length, height and width, set the wall to one unit thick and use the joint you will actually lay: about 3/8 in (10 mm) for ordinary mortar, about 2 mm for thin-joint adhesive. You get blocks per unit of wall area and the volume of mortar or adhesive in the joints. Hollow block laid with mortar on the face shells only uses less mortar than the full-bed figure shown here.
Why is mortar in cubic feet or cubic metres and not in bags?
Because bag yield differs between products and mortar types, and real usage depends on the brick and the mason. The calculator gives the theoretical joint volume plus a loss allowance; divide by the yield per bag printed on your mortar to get the number of bags.
Part of Home Improvement Calculators