Mortar Calculator

A mortar calculator turns a wall into bags. It finds the wall area, subtracts openings, counts the bricks or blocks, adds waste, and divides by how many units a bag lays. It also gives the mortar volume and, for masonry cement, the sand. For a 20 × 8 ft block wall that is 189 blocks and 15 bags of 80 lb mix.

This is a mortar estimator and a brick mortar calculator in one. It covers a concrete block mortar calculator use, a masonry mortar calculator use, and a mortar mix calculator use. Pick brick, block or a custom unit, set the joint thickness, and choose pre-blended mix, masonry cement with sand, or mix by volume.

The bag yields come from manufacturer data sheets and are editable. The price on the page is a placeholder. The result is an estimate, so buy a little extra and follow your plans and the product label.

The unit count sets everything else. Each unit occupies its own face plus a joint, so the number per square foot is 144 divided by (length plus joint) times (height plus joint) in inches. A standard 8 × 8 × 16 inch block is 7 5/8 by 15 5/8 inches actual, and with a 3/8 inch joint it covers 8 by 16 inches, which is 1.125 blocks per square foot. The Concrete Masonry and Hardscapes Association uses the same unit and gives 119 blocks per 100 sq ft including 5 percent waste.

Standard modular brick is 2 1/4 by 7 5/8 inches, which with a joint is 2 5/8 by 8 inches, or 6.857 bricks per square foot. A 100 sq ft wall is 686 bricks before waste.

The per 100 sq ft table lists both units. Enter openings so doors and windows are not counted.

QUIKRETE says an 80 lb bag of Mortar Mix, formulated as Type N, or Mason Mix, formulated as Type S, lays up to 37 standard bricks or 13 standard blocks. The calculator divides the unit count by that yield and rounds up. A 60 lb bag is taken as three quarters of an 80 lb bag, and a 40 lb bag as half. No maker figure was found for Type M, so it uses the same yield; use the override box if your bag says otherwise.

The types differ in strength and ingredients, not in the number of units a bag lays. QUIKRETE lists minimum compressive strengths of 2,500 psi for Type M, 1,800 psi for S and 750 psi for N under ASTM C270. Which type a wall needs is a design choice. Follow your plans, your building authority and the product label, and ask the designer if the type is not stated.

The 100 sq ft block wall needs 10 bags and the brick wall 20. The wall sizes table gives common walls.

Mortar volume matters when you mix on site or order bulk. The calculator uses QUIKRETE's masonry cement figures, where about 2.75 cubic feet of mortar lays 46 standard blocks or 144 standard bricks. That is 0.0598 cubic feet per block and 0.0191 per brick, which include normal waste at the joints, furrowing and droppings.

For 100 sq ft of block that is 6.73 cubic feet, or 0.190 cubic metres, before waste. For brick it is 13.10 cubic feet. A thicker joint holds more mortar, so the calculator scales each unit's volume by the joint area around it. At 1/2 inch, the brick wall's volume rises from 13.75 to 17.44 cubic feet.

The volume depends on the unit and the bedding, so the figure is a planning number, not a measured one.

If you buy masonry cement, you add sand. QUIKRETE's Type S masonry cement sheet says one bag mixed with 240 lb of mason's sand yields about 2.75 cubic feet of mortar and lays about 46 blocks or 144 bricks, and recommends 2.25 to 3 parts of sand to 1 part of cement. The Concrete Masonry and Hardscapes Association reports 1 ton of sand per 8 bags, which matches 240 lb per bag. Its own figure for a 70 lb bag is about 30 hollow units, which is lower, so use the override box if your supplier or mason works to that figure.

The mix by volume mode uses ASTM C270 proportions of portland cement, lime and sand. Wikipedia lists Type S as 1 : 1/2 : 4 1/2 and Type N as 1 : 1 : 6. Sand is limited to 2.25 to 3 times the cement and lime combined, and the calculator uses the upper end, so Type M is 1 : 1/4 : 3 3/4. The ratio table gives lime and sand for 1 to 5 cubic feet of cement. These are dry volumes, and the sand used on the job must meet the specification.

The default 3/8 inch joint is the one built into the nominal block size. A thicker joint fits fewer units and uses more mortar. For 100 sq ft of brick, a 1/4 inch joint needs 768 bricks with waste and a 5/8 inch joint 637. The joint table shows the bags.

Waste covers cuts, breakage and droppings. The default is 5 percent, the same allowance built into the association's 119 blocks per 100 sq ft. Use more for many corners and openings.

Cost is bags times the price per bag. The page uses a placeholder of $14 per bag, so the 20 × 8 ft block wall is $210. The cost table shows other bag prices. Sand, lime, water, tools and labour are not included, and mortar is usually a small share of the wall.

Enter the wall as length and height, or as a known area if the wall has several parts. Put doors, windows and other openings in the openings box, and the wall area drops by that much. A 20 × 8 ft wall with a 20 sq ft opening needs 165 blocks with waste instead of 189.

If your unit is not a standard brick or block, choose custom and enter its actual length and height. The calculator treats custom units like brick, scaling the joint area. Irregular stone uses far more mortar than uniform units, so treat that result as a minimum and ask a mason.

Grout, which fills block cores, is not included here. The CMU block calculator covers blocks, mortar, sand and core-fill together.

This is an estimate for planning and ordering. Real walls use different amounts of mortar depending on the mason, the unit, the bedding method, the weather and the amount of cutting. The bag yields are the manufacturer's figures for particular products, so another brand may differ, and the 'up to' wording means yields can be lower in practice.

The calculator does not design a wall or choose a mortar type, and it makes no statement about strength or structural performance. Follow your plans, local code and the product label, and have a qualified professional check any structural masonry. For a related calculation, see the CMU block calculator and, for pricing a job, the markup calculator.