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Brick and Block Calculator

Find out how many bricks or concrete blocks to order for a garden wall, a house extension or a barbecue. Enter the wall size, take off the doors and windows, pick the type of unit and get a count with a breakage allowance included.

Quick answer: A wall 20 ft long and 6 ft high needs about 851 modular bricks, including 5% extra for cuts and breakage.

Your measurements

ft
ft
sq ft
%
$

Bricks to buy

851bricks

Wall area to cover
120 sq ft
Units per square foot
6.75
Count with no waste
810 bricks
Count with 5% extra
851 bricks

Counts include the mortar joints and cover one layer. Mortar is not included, so ask your supplier how much to buy for your joint size.

How to use this calculator

  1. Measure the length and the height of the wall in feet.
  2. Pick modular brick, utility brick or standard concrete block.
  3. Enter the total area of any doors or windows to subtract from the wall.
  4. Keep the extra at 5% for a simple wall, or raise it for a pattern with many cuts.
  5. Add a price per unit if you want an estimated material cost.

How the numbers are calculated

The calculator multiplies the length by the height and subtracts the openings to get the area of masonry. It then multiplies that area by the number of units that fit in one square foot, including a normal mortar joint.

About 6.75 modular bricks, 3 utility bricks or 1.125 concrete blocks cover a square foot of wall. The result is rounded up after your waste percentage is added, so you finish the wall without a second delivery.

Worked example

A wall 20 ft long and 6 ft high covers 120 sq ft. In modular brick that is 120 times 6.75, which is 810 bricks. Adding 5% for cuts and breakage gives 851 bricks. The same wall in 8 by 16 concrete block needs 135 blocks, or 142 with 5% extra.

Tips before you buy

  • Order all your bricks at once. Colors vary between batches, and a later delivery may not match.
  • Mix bricks from several packs as you lay them so any slight color difference blends in.
  • Mortar is not included in the count, so ask your supplier how much to buy for your joint size and wall.
  • Plan the wall length around the brick size where you can. Cutting fewer bricks saves time and reduces waste.
  • Free-standing walls over about 3 feet usually need piers or reinforcement, and many places require a permit. Check locally.

Frequently asked questions

How many bricks are in a square foot?

A wall of modular bricks takes about 6.75 bricks per square foot, including the mortar joint. Utility bricks need about 3 per square foot.

How many bricks do I need for 100 square feet?

About 675 modular bricks with no waste, or roughly 710 with a 5% allowance for cuts and breakage.

How many concrete blocks do I need for a wall?

A standard 8 by 16 inch block face covers 0.89 square feet with its joint, so you need about 1.125 blocks per square foot of wall.

Does the calculator work for a double-thickness wall?

No, it counts one layer. For a double wall, multiply the result by two.

Quick answers

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These results are estimates for planning purposes. Material sizes, densities and local requirements vary, so confirm quantities with your supplier or a qualified contractor before ordering.

Last updated October 11, 2026.