Mortar Calculator — Bags for Brick & Block
Estimate the mortar for a brick or block wall. Enter how many units you are laying (or use the wall-area note), pick the unit type, and get the bags of mortar mix plus the sand to add.
How to use this calculator
- Count the bricks or blocks you are laying. For a wall, multiply area by ≈7 bricks or ≈1.125 blocks per square foot.
- Pick the unit type — blocks use far more mortar per unit than bricks.
- Use premixed mortar (sand included) for convenience, or masonry cement plus sand for larger jobs.
- Buy 5–10% extra; mortar that sets in the tub or drops off the trowel is lost.
The formula
Mortar is estimated from the number of units, since each joint uses a predictable amount.
Bags = units ÷ units per bag. An 80 lb bag of mortar mix lays about 30 standard bricks or about 13 standard 8×8×16 blocks.
If site-mixing with masonry cement and sand, plan roughly 1 cubic foot of sand per bag of cement.
Worked example
Laying 500 standard bricks.
Per bag ≈ 30 bricksBags = 500 ÷ 30 = 16.7 → 17 bags
About 17 bags of 80 lb mortar mix to lay 500 standard bricks.
Frequently asked questions
How many bricks does a bag of mortar lay?
An 80 lb bag of mortar mix lays roughly 30 standard bricks or about 13 standard concrete blocks. Larger joints and rougher units reduce that count.
How much mortar do I need for a block wall?
Estimate the blocks first (about 1.125 standard blocks per square foot of wall), then divide by 13 blocks per bag. A 100 sq ft wall is ~113 blocks, or about 9 bags.
Premixed mortar or masonry cement and sand?
Premixed mortar (sand already included) is easiest for small jobs. For larger walls, buying masonry cement and sand separately and mixing on site is cheaper.