Concrete Block Calculator

Estimate standard 8×8×16 inch concrete blocks and mortar bags for any wall. Enter wall dimensions, adjust for breakage, and optionally price it out.

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How to use this calculator

  • Enter the wall’s length and height in feet.
  • Keep the default 5% breakage allowance — blocks chip in handling.
  • Add your supplier’s price per block for a cost estimate.

The math behind it

A standard 8×8×16 in block covers 128 square inches of wall face, so one square foot of wall needs 144 ÷ 128 = 1.125 blocks. Total = wall area × 1.125, plus waste, rounded up. Mortar estimate assumes roughly 35 blocks per 60 lb bag of mortar mix.

FAQs

How many blocks do I need for a wall?

A 20 ft long × 4 ft tall wall needs about 95 blocks with 5% waste. The rule of thumb: multiply wall square footage by 1.125.

How much mortar per block?

Roughly one 60 lb bag of mortar mix lays about 35 standard blocks. Buy a couple extra bags — running out mid-wall is worse than having leftovers.

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