Concrete Block Calculator
Estimate blocks and mortar bags for a wall
Frequently Asked Questions
A standard 8×16-inch concrete or cinder block (CMU), including a standard 3/8-inch mortar joint, covers 128 square inches, or about 0.89 square feet of wall face — so you need roughly 1.125 blocks per square foot of wall.
A common rule of thumb is about 3 bags of mortar mix (80 lb bags) per 100 blocks for standard 3/8-inch joints, which works out to roughly 1 bag per 33 blocks. Actual usage varies with joint thickness and mason technique.
Yes — most contractors add 5-10% extra to account for cuts, breakage, and layout adjustments. This calculator lets you set your own waste percentage.
No — enter the gross wall area and then separately subtract the area of any door or window openings from your total before ordering material, since this calculator doesn't automatically account for openings.