Concrete Block Calculator
Calculate how many concrete blocks you need for a wall with this free online concrete block calculator. Get courses, mortar bags, waste and total block cost.
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How to use Concrete Block Calculator
- 1Choose feet and inches or metres and millimetres, then pick the block face size
- 2Enter the wall length and height, plus the area of any doors or windows
- 3Read the number of blocks with waste, the courses, mortar bags and the cost if you add a block price
Frequently asked questions
How many concrete blocks do I need per square foot?▾
A standard 8 x 8 x 16 inch block covers 16 x 8 inches including the mortar joint, so you need 1.125 blocks per square foot, or 112.5 blocks per 100 square feet.
How many blocks do I need for a 20 ft by 6 ft wall?▾
A 20 x 6 ft wall is 120 square feet. At 1.125 standard blocks per square foot that is 135 blocks, or 142 blocks with 5% waste.
How much mortar do I need for concrete blocks?▾
As a rule of thumb, one 80 lb bag of mortar mix lays about 32 standard blocks, so 142 blocks need about 5 bags. Buy a little extra for cutting and spillage.
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