Mortar Calculator

The Mortar Calculator estimates how many mortar bags you need when you already know your brick or block count. Select brick or concrete block size, enter piece count, choose bag weight, and get rounded-up bag totals with optional cost. A waste allowance helps you buy a little extra for jobsite spill and trimming.

Mortar bag formula

Mortar quantity is based on how many bricks or blocks one bag covers:

$$\text{Bags} = \left\lceil \frac{\text{Pieces} \times (1 + \text{Waste\%})}{\text{Yield per bag}} \right\rceil$$

Yield varies by brick or block size and mortar bag weight. An 80 lb bag typically covers about 40 modular bricks or 12 eight-inch concrete blocks. Results are always rounded up because mortar is sold in whole bags.

When to use this tool

Use this calculator when you already know piece count from a takeoff or from our Brick and Mortar Calculator. For full wall planning with openings and bond patterns, the brick and mortar tool estimates both bricks and mortar from wall dimensions. Pair results with the Cement Calculator when mixing mortar from raw cement, sand, and water.

Frequently Asked Questions

How many bricks does an 80 lb mortar bag cover?

It depends on brick size. Modular bricks average about 40 to 45 per 80 lb bag. Queen and king size bricks cover fewer pieces because joints and bed area increase.

How do I calculate mortar for concrete blocks?

Divide your block count by the yield per bag for your block width. Eight-inch blocks typically need about 11 to 13 blocks per 80 lb bag.

Should I add extra mortar?

Yes. A 10% waste allowance is common on construction jobs to cover spill, partial bags, and cutting losses at corners and openings.

Why are bags rounded up?

Mortar is sold in full bags at retail. If the exact calculation is 8.3 bags, you need to purchase 9 bags to complete the wall.

What is the difference between this and the brick and mortar calculator?

This tool starts from a known brick or block count. The brick and mortar calculator starts from wall length, height, openings, and bond pattern to estimate both bricks and mortar together.

Report

Mortar Calculator