Mortar Calculator
Find how much mortar you need to lay blocks or bricks, and how much portland cement, hydrated lime, and sand to mix it from a ratio such as Type N or Type S. Start from the number of blocks or bricks, the wall area, or the mortar volume. For bags of premixed mortar mix, use the Concrete Block Calculator or the Brick Calculator.
- Choose US or Metric. This sets the units, the blocks and bricks you can choose, and the bag sizes: 94 and 47 lb cement, 50 lb lime, and 70, 60, and 50 lb sand for US, and 40, 25, and 20 kg cement, 25, 20, and 10 kg lime, and 800 kg bulk bags and 22.5 and 20 kg bags of sand for Metric.
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Under Measure by, choose what you know:
- Blocks or bricks: enter how many you'll lay.
- Wall area: enter the area of the wall face, with doors and windows subtracted.
- Mortar volume: enter the volume of mortar if you already know it, for example for stone or a block that is not listed.
- For blocks or bricks and wall area, choose the block or brick. Each choice shows the mortar the calculator uses for one unit.
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Choose a mix. With Custom mix, enter the parts of
cement, lime, and sand by volume. Fractions such as
1/2and4 1/2work. Leave lime blank for a mix without lime. - Keep the mortar yield at 100% unless you know your sand yields more or less mortar. Reset to 100% brings it back.
- The Sand density field shows a typical density. If your supplier gives a density, enter it. If your sand bag is not listed, enter its weight or volume in Custom sand bag size.
- Keep the 10% waste allowance or change it. Optionally, enter a price for cement, lime, and sand to estimate the cost of each and the total.
How much mortar you need
The calculator first finds the volume of mixed mortar:
Mortar = number of blocks or bricks × mortar per block or brick
With a wall area, the number of blocks or bricks is the wall area ÷ the face area of one block or brick, including one mortar joint. The calculator doesn't round that number up, since part blocks also take part of the mortar. Then it adds the waste allowance: total mortar = mortar × (1 + waste % ÷ 100).
The mortar for one block or brick comes from the sources' estimates:
| Block or brick | Mortar each |
|---|---|
| 8 × 8 × 16 in block | 0.097 ft³ (2.74 L), 62 per 6 ft³ |
| Modular brick | 0.02 ft³ (0.57 L), 300 per 6 ft³ |
| 440 × 215 mm block | 0.67 L, 1,500 per m³ |
| 215 × 65 mm brick | 0.56 L, 1,800 per m³ |
| 390 × 190 mm block | 1.33 L, 750 per m³ |
| 230 × 76 mm brick | 0.6 L, about 1,667 per m³ |
The US values come from Table 2 of TEK 04-02A by the Concrete Masonry & Hardscapes Association (CMHA): one batch of Type N mortar with 6 ft³ of sand lays about 62 standard blocks, with mortar on the face shells only, or 300 brick-size units. CMHA notes that the values already include a normal amount of waste, so with the 10% allowance on top, the calculator errs on the high side. Set the waste allowance to 0% to get CMHA's estimate. The block value doesn't depend on the block width, because only the face shells get mortar.
The UK values come from Tarmac's data sheet for its ready-to-use mortar, which gives 1,500 blocks 100 mm thick and 1,800 to 2,000 bricks per cubic meter. The calculator uses the lower brick count. For 75 mm blocks, Tarmac's figures work out to about 0.5 L each, and for 150 mm blocks about 1 L. Enter those with Mortar volume. The Australian and New Zealand block value comes from Firth, which says about 750 blocks per cubic meter without naming a block width, so treat it as a rough guide. The brick value comes from Cockburn Cement, which gives 0.6 m³ of damp bricklaying sand for 1,000 standard bricks.
Why this differs from the Concrete Block Calculator
For the same blocks, this calculator shows about 1.6 times as much mortar as the Concrete Block Calculator suggests in premixed bags. That calculator uses Sakrete's yield for its premixed mortar, 12 blocks per 80 lb bag, or about 0.061 ft³ of mortar per block. CMHA's own table also puts mortar mixed on site above premix: 62 blocks per batch with 6 ft³ of sand, but 16 blocks per 80 lb bag of premix. Site-mixed estimates allow for mortar that is dropped or left over. If you want bags of premix, use that calculator.
Mix ratios and mortar types
Mortar mixes are given as parts by volume of cement, lime, and sand. The calculator offers three common mixes:
| Mix | What goes in |
|---|---|
| 1 : 1 : 6 (Type N) | Portland cement, hydrated lime, and sand. A general-purpose mortar for above-grade walls |
| 1 : ½ : 4½ (Type S) | Portland cement, hydrated lime, and sand. A higher-strength mortar |
| 1 : 3 masonry cement | Type N or Type S masonry cement and sand. Masonry cement already contains lime, so you add none |
The Type N and Type S ratios are the ones in CMHA's table. ASTM C270, the US mortar standard, allows 2¼ to 3 times as much sand as cement and lime combined, and these mixes use the upper end. Some manufacturers suggest less sand: Quikrete gives 4¾ to 5¾ parts of sand for Type N, which takes up to about a quarter more cement. Holcim UK suggests 1 : 1 : 5 for a general cement and lime mortar. Enter those in Custom mix.
Type M (1 : ¼ : 3¾) and Type O (1 : 2 : 9) are less common in home projects: Type M is for heavily loaded walls below grade, and Type O for lightly loaded interior walls. Enter them in Custom mix too. The descriptions here are general information. Which type your wall needs depends on its design and local building codes, so follow them when they specify a mortar.
Custom mixes count cement as portland cement. If you use masonry cement in a custom ratio, US bag counts stay the same, because a bag of either is measured as 1 ft³. Metric bag counts come out higher than you need, because masonry cement is lighter than portland cement for its volume.
The calculator doesn't cover lime mortars without cement, such as natural hydraulic lime (NHL), or render, stucco, and the grout that fills block cores. Add water a little at a time until the mortar is workable. The amount depends on the product and how damp the sand is.
Cement, lime, and sand from the mortar
The amounts of the materials are:
Sand = total mortar ÷ (mortar yield ÷ 100)
Cement = sand × cement parts ÷ sand parts
Lime = sand × lime parts ÷ sand parts
The mortar yield is the volume of mixed mortar as a share of the damp, loose sand that goes into it. The calculator uses 100%, the rule of thumb of the Brick Industry Association (BIA): 1 cubic foot of loose, damp sand yields about 1 cubic foot of mortar. The cement and lime fill the spaces between the sand grains, so they add almost nothing to the volume. If you've measured a different yield with your sand, enter it.
In the US, mortar is measured by the bag: a 94 lb bag of portland cement is 1 ft³, a 47 lb bag is ½ ft³, and a bag of masonry cement counts as 1 ft³ whatever it weighs. Hydrated lime weighs about 40 lb/ft³, so a 50 lb bag is 1¼ ft³. Metric bags are sold by weight, so the calculator converts cement at 94 lb/ft³ (1,506 kg/m³) and lime at 40 lb/ft³ (641 kg/m³), the densities CMHA uses. If your bags give a different volume, the bag counts shift by the same share. Bag counts are rounded up to whole bags.
Sand weight
The weight of the sand is:
Sand weight = sand volume × sand density
The calculator uses a typical sand density of 100 lb/ft³ (1.602 t/m³), the same as the Sand Calculator, and counts bags of sand by weight. CMHA uses 80 lb/ft³ for damp, loose sand, which is the weight of the dry sand in a cubic foot that moisture has fluffed up. At 100 lb/ft³, the calculator shows about 25% more weight than that, so if you buy by weight you may have some left over. To match CMHA's estimate, enter 80 lb/ft³ in Sand density.
Examples
100 blocks with Type N mortar
100 blocks of 8 × 8 × 16 in take 100 × 6/62 = 9.68 ft³ of mortar. With a 10% waste allowance, that's 10.65 ft³ (0.39 yd³). The sand is also 10.65 ft³, and the cement and lime are each a sixth of that, about 1.77 ft³. That's 2 bags of 94 lb portland cement (or 4 of 47 lb), 2 bags of 50 lb hydrated lime, and 0.53 US tons of sand, or 16 bags of 70 lb. At $15 per bag of cement, $12 per bag of lime, and $40 per US ton of sand, the cost is $75.29.
1,000 UK bricks
1,000 bricks of 215 × 65 mm take 1,000 ÷ 1,800 = 0.56 m³ of mortar, or 0.61 m³ with 10% added. For a 1 : 1 : 6 mix, the cement is a sixth of the sand, about 101.85 L, which weighs about 153 kg: 7 bags of 25 kg. The lime weighs about 65 kg: 3 bags of 25 kg. The sand weighs 0.98 tonnes: 2 bulk bags of 800 kg, or 44 bags of 22.5 kg.
Checking against CMHA's table
Enter 62 blocks with a 0% waste allowance. The calculator shows 6 ft³ of sand and 1 ft³ each of cement and lime, the Type N batch in CMHA's table: 1 bag of 94 lb cement and 1 bag of 50 lb lime.
FAQ
About 10.65 ft³ for 100 standard 8 × 8 × 16 in blocks with a 10% waste allowance, or 9.68 ft³ without it. For Type N mortar, that's 2 bags of 94 lb portland cement, 2 bags of 50 lb hydrated lime, and about 0.53 US tons of sand.
1 part portland cement, ½ part hydrated lime, and 4½ parts sand by volume, the Type S mix in CMHA's table. With masonry cement, mix 1 part Type S masonry cement with 3 parts sand and no lime.
About 6 ft³ for Type N mortar: 1 : 1 : 6 means 6 parts of sand for each part of cement, and a 94 lb bag of portland cement is 1 ft³. At 100 lb/ft³, that's about 600 lb of sand. For Type S it's 4½ ft³, and for 1 : 3 masonry cement mortar it's 3 ft³ per bag.
About 12 standard blocks or 35 bricks per 80 lb bag of premixed mortar, according to Sakrete. That's less mortar per block than this calculator uses for mortar mixed on site. To count bags of premix, use the Concrete Block Calculator or the Brick Calculator.
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