🧰 Mortar Calculator
Enter your number of bricks or blocks and joint thickness to estimate how many bags of mortar mix your project will need.
What This Calculator Does
The mortar calculator estimates how many bags of pre-mixed mortar you need to lay a given number of bricks or concrete masonry units (CMU blocks), factoring in joint thickness and a waste allowance.
How the Calculation Works
Industry rule-of-thumb coverage rates are used as a starting point: roughly 7 standard bricks or 28 standard 8x8x16 inch blocks per 80-pound bag of mortar mix, assuming typical 3/8 inch joints. This calculator divides your total unit count by that coverage rate, then adjusts up or down based on whether your joints are thicker or thinner than standard, and finally adds your chosen waste percentage to account for spillage, tooling, and mixing losses before rounding up to a whole number of bags.
Tips for Estimating Mortar
- Joint thickness has a big effect on mortar usage — thicker joints or uneven, reclaimed units use noticeably more mortar per unit.
- A 10 percent waste allowance is a reasonable starting point for most jobs; increase it for smaller or more detailed work.
- Type S mortar is common for below-grade and structural work, while Type N suits most above-grade residential masonry — check your local code for requirements.
Note: These figures are general estimates for planning purposes. Actual coverage varies by unit size, mason technique, and mix brand, so confirm quantities with your material supplier.