Mortar Calculator
Calculate the exact number of mortar bags needed for your brick or concrete block wall project. Enter the number of units, brick size, and bag weight for instant mortar estimates with charts and breakdowns.
About This Calculator
Our free online mortar calculator helps builders, contractors, and DIY enthusiasts determine the exact number of mortar bags needed for any brick or concrete block wall project. Whether you are building a retaining wall, a garden boundary, or a structural wall, knowing how much mortar to buy saves time, money, and reduces material waste.
Calculate mortar by entering the number of bricks or concrete blocks in your project, selecting the block or brick size from common presets (modular bricks, queen size, king size, utility bricks, or 4–12 inch concrete blocks), and adjusting the yield per bag. The calculator uses standard industry yields: for example, an 80 lb bag of mortar covers approximately 40–45 modular bricks or 11–13 eight-inch concrete blocks. You can also enter custom yield values and bag weights.
Regional Notes
India: Mortar is typically sold in 50 kg bags in India. Common mix ratios are 1:4 or 1:6 (cement:sand). The yield per bag varies based on brick size (standard Indian brick ~230 × 110 × 75 mm) and joint thickness.
US: Standard mortar bags are 80 lb (36.3 kg). Type N mortar is most common for above-grade exterior walls. Common block sizes include 4", 6", 8", 10", and 12" nominal widths.
UK: Mortar is available in 25 kg bags. Standard UK brick size is 215 × 102.5 × 65 mm. Mix ratios of 1:4 or 1:5 (cement: sand) with plasticizer are common for general brickwork.
The mortar calculation formula is simple: divide the total number of bricks or blocks (including waste allowance) by the yield per bag, then round up to the nearest whole bag. Always add 10% for waste and breakage, as recommended by construction industry standards.
Frequently Asked Questions
How much mortar do I need per brick?
A standard 80 lb (36.3 kg) bag of mortar typically yields enough to lay 40–45 modular bricks, 34–39 queen size bricks, or 28–33 king size bricks. For concrete blocks, one bag yields approximately 10–17 blocks depending on the block size. The exact yield varies by mortar type, joint thickness, and workmanship.
How many bags of mortar per 1000 bricks?
For 1000 modular bricks, you need approximately 23–25 bags of mortar (80 lb/36.3 kg each) at an average yield of 40–45 bricks per bag. For utility bricks with a lower yield of 23–28 per bag, you would need about 36–44 bags. Always add 10% extra for waste and breakage.
How many concrete blocks per bag of mortar?
An 80 lb bag of mortar yields approximately 15–17 four-inch blocks, 12–14 six-inch blocks, 11–13 eight-inch blocks, or 10–12 twelve-inch blocks. These estimates assume standard mortar joint thickness of 3/8 inch. Actual yield may vary based on block design and site conditions.
What is the mortar mix ratio for brick walls?
Common mortar mix ratios include 1:3 (cement to sand) for high-strength applications, 1:4 for general brickwork, 1:5 for load-bearing walls, and 1:6 for non-load-bearing walls. Type N mortar (1:1:6 cement:lime:sand) is most common for above-grade exterior walls, while Type S (1:1:4.5) is used for below-grade applications.
How much does a bag of mortar weigh?
Standard pre-mixed mortar bags typically weigh 80 lb (36.3 kg) in the US and 25 kg or 50 kg in other regions. Lightweight mortar options are also available. Always check the manufacturer's specifications for exact bag weight and coverage information.
Should I add extra mortar for waste?
Yes, it is recommended to add 10% extra mortar to account for waste, spillage, and breakage during construction. This practice ensures you do not run out of materials mid-project. Buying an extra bag or two is also advisable for future repairs or touch-ups.
What is the difference between Type N, Type S, and Type M mortar?
Type N mortar (minimum 750 psi) is the most common general-purpose mortar for above-grade exterior walls and interior load-bearing walls. Type S mortar (minimum 1800 psi) has higher strength for below-grade applications and structures under heavy loads. Type M mortar (minimum 2500 psi) is the highest strength and is used for heavy-load applications like retaining walls and foundations. Type O mortar (minimum 350 psi) is a low-strength mortar for interior non-load-bearing walls.
How do I calculate mortar for a brick wall?
First, calculate the total number of bricks needed using wall dimensions and brick size. Then divide the number of bricks by the mortar yield per bag (typically 40–45 for modular bricks with standard 3/8" joints). Multiply by 1.1 to add 10% waste, and round up to the nearest whole bag. For example, 5000 modular bricks ÷ 40 per bag × 1.1 = 138 bags.