Introduction
The Mortar Calculator helps you figure out how much mortar you need for your construction project. Mortar is the paste that holds bricks, blocks, and stones together. Getting the right amount is important. Too little means extra trips to the store, and too much means wasted money. This tool lets you enter the size of your wall or project and quickly tells you how many bags of mortar mix you need to buy. This calculator helps you plan materials for a brick wall, block laying, or a small repair job. Just plug in your numbers to get an accurate estimate.
How to Use Our Mortar Calculator
Enter your project details and wall dimensions below, and this calculator will tell you how much mortar you need, including total volume, weight, number of pre-mixed bags, and a breakdown of raw materials like cement, lime, and sand.
Unit System: Choose between Imperial (feet and inches) or Metric (meters and centimeters) to match how you measure your project.
Project Type: Select the tab that matches your job: Brick Wall, Block Wall, Stone Wall, Paving, Plastering, or Tiling. Each type has its own set of inputs.
Brick Size / Block Size: Pick a preset size like Standard or Modular, or choose Custom to type in your own width, height, and length. This helps the calculator figure out how much mortar fits between each unit.
Mortar Joint Thickness: Enter the thickness of the mortar joints between your bricks or blocks. A common value is ⅜ inch (about 1 cm).3
Wall Length: Enter how long your wall is. You can add more wall sections if your project has multiple walls by clicking the "Add Another Wall Section" button.
Wall Height: Enter how tall your wall will be from bottom to top.
Wall Thickness: Choose Single Wythe (one layer of bricks or blocks), Double Wythe (two layers), or Custom to enter your own thickness value.
Stone Wall Thickness: For stone walls, type in the wall thickness directly since stone sizes vary.
Paving Inputs: Enter the area length, area width, joint width, joint depth, and the side length of your square pavers or flagstones.
Plastering Inputs: Enter the wall length, wall height, and the thickness of the plaster coat you plan to apply.
Tiling Inputs: Enter the area length, area width, square tile side length, grout joint width, and bed thickness (the mortar layer under the tiles).
Mortar Mix Type: Select the mix that fits your project. Type N is for general use, Type S is for structural work, Type M is for high-strength needs, and Type O is for interior jobs.2 Each type has a different ratio of cement, lime, and sand.
Waste Factor: Enter a percentage to account for spills, dropped mortar, and other waste. As a general rule, add 15% to 25% to the net mortar quantity.3
Calculate Mortar: Click this button to see your results, including mortar volume with and without waste, total weight, the number of pre-mixed bags needed in different sizes, and a full breakdown of raw cement, lime, and sand quantities.
What Is Mortar?
Mortar is the paste-like material that holds bricks, blocks, and stones together in construction. It is made by mixing cement, lime, sand, and water.1 When mortar dries, it creates a strong bond between masonry units and helps spread weight evenly across a wall. Without the right amount of mortar, a structure can crack, shift, or even collapse over time.
Common Mortar Mix Types
Not all mortar is the same. ASTM C270 sets the lime per part of cement for each type: ¼ part for Type M, over ¼ to ½ for Type S, over ½ to 1¼ for Type N and over 1¼ to 2½ for Type O, with sand no more than 3 times the combined volume of cement and lime.1 The ratios below (cement : lime : sand, by volume) fall inside those limits:
- Type N (1:1:6). The general all-purpose mortar, with good bonding and workability.2 BIA recommends it for above-grade veneer and non-loadbearing walls, parapets and chimneys.2
- Type S (1:0.5:4.5). An all-purpose mortar with higher compressive and flexural bond strength.2 BIA recommends it for reinforced or loadbearing walls above grade, and as the alternate for foundations and retaining walls.2 It is the usual choice in high-wind and high-seismic areas.2
- Type M (1:0.25:3.375). A high compressive-strength mortar, but not very workable.2 BIA recommends it for foundation walls, retaining walls, sewers and manholes, and for most exterior paving.2
- Type O (1:2:9). A low-strength mortar used mostly for interior work and restoration.2 It is often used for repointing older brickwork.2
Where Mortar Is Used
Mortar is needed in many types of construction projects beyond just brick walls. This calculator covers six common uses:
- Brick walls – Mortar fills the joints between bricks. A standard joint is about ⅜ inch thick.3 Single-wythe walls use one layer of brick, while double-wythe walls use two layers with mortar between them.
- Block walls – Concrete blocks (commonly 8″ × 8″ × 16″) also require mortar in the joints. Because blocks are larger than bricks, fewer joints are needed per square foot, so less mortar is used.
- Stone walls – Natural stone shapes vary, so stone walls need more mortar to fill the gaps. Roughly 30% of a stone wall's volume can be mortar.
- Paving – Mortar fills the joints between pavers or flagstones. The amount depends on joint width, joint depth, and the size of the pavers.
- Plastering – A thin layer of mortar is spread over a wall surface to create a smooth finish. Plaster coats are usually ¼ to ½ inch thick.
- Tiling – Mortar serves as the bed that holds tiles in place, and grout (a form of mortar) fills the narrow gaps between tiles.
Why Accurate Mortar Estimates Matter
Ordering too little mortar means your project stops while you wait for more material. Ordering too much wastes money and creates cleanup problems, since ASTM C270 requires all mortar to be used within 2½ hours after mixing.1 A good estimate saves time, reduces waste, and keeps your project on budget. Knowing the exact square footage of your walls or surfaces is the first step toward an accurate calculation.
Understanding the Waste Factor
In real-world construction, some mortar always gets wasted. It drops off the trowel, sticks to the mixing board, or dries out before it can be used. As a general rule, BIA adds 15% to 25% to the net mortar quantity.3 Use the high end if you are working in hot or windy conditions where mortar dries faster, or if you are less experienced.
Pre-Mixed Bags vs. Raw Materials
You can buy mortar in two ways. Pre-mixed bags already contain the cement, lime and dried sand, so you just add water.6 QUIKRETE's Mason Mix, for example, comes in 60 lb, 80 lb and 94 lb bags.5 They are convenient for small to medium jobs. For larger projects, buying raw materials separately (Portland cement, hydrated lime, and sand) is usually cheaper. This calculator shows both options so you can pick the best one for your project size and budget.