Mortar Calculator
Calculate mortar accurately for your build. Get material quantities, waste allowances, and project cost breakdowns. Enter your values for instant results.
Calculator
Adjust values & calculateSite-Mix Materials (Ratio 1:1:6)
Formula
The number of bricks is calculated from the wall area divided by the area of one brick module (brick plus joint). Mortar volume per brick includes horizontal bed joints and vertical head joints. Material quantities are derived from the mortar type mix ratio applied to total mortar volume.
Last reviewed: December 2025
Worked Examples
Example 1: Standard Residential Brick Wall
Example 2: Garden Retaining Wall
Background & Theory
The Mortar Calculator applies the following established principles and formulas. Structural and construction engineering is governed by fundamental load analysis, material science, and regulatory standards that ensure the safety and durability of built structures. The primary distinction in load analysis is between dead loads — the permanent self-weight of structural elements, finishes, and fixed equipment — and live loads, which represent variable occupancy, furniture, and environmental forces such as wind and snow. These are combined using factored load equations, such as the ASCE 7 formula U = 1.2D + 1.6L, where D is dead load and L is live load. Concrete mix design is governed by the water-cement (w/c) ratio, which is the primary determinant of compressive strength and durability. A w/c ratio of 0.40–0.45 typically yields concrete with 28-day compressive strengths of 30–40 MPa. Common mix ratios by weight for structural concrete are approximately 1 part cement : 1.5–2 parts sand : 3 parts coarse aggregate. Structural steel is characterized by its yield strength (the stress at which permanent deformation begins, typically 250–350 MPa for mild steel) and ultimate tensile strength (typically 400–500 MPa). Mid-span deflection of a simply supported beam under a central point load is given by δ = FL³ / (48EI), where F is force, L is span length, E is Young's modulus, and I is the second moment of area. Building insulation is rated by R-value, a measure of thermal resistance in units of m²·K/W (SI) or ft²·°F·h/BTU (imperial). Higher R-values indicate greater resistance to heat flow. Foundation design depends on the allowable bearing capacity of the underlying soil, which ranges from approximately 75 kPa for soft clay to over 10,000 kPa for bedrock. Drainage gradients for surface water are typically specified as a minimum of 1–2% slope away from building foundations to prevent hydrostatic pressure and water infiltration.
History
The history behind the Mortar Calculator traces back through the following developments. The history of construction engineering spans thousands of years of accumulated empirical knowledge and, more recently, rigorous scientific analysis. The ancient Egyptians built the Great Pyramid of Giza around 2560 BCE using an estimated 2.3 million stone blocks, demonstrating sophisticated logistics, geometry, and workforce organization. Roman engineers advanced the field dramatically through the use of pozzolanic concrete — a mixture of volcanic ash, lime, and seawater — enabling the construction of the Pantheon dome (43.3 m diameter, completed around 125 CE) and a vast network of aqueducts and roads across the empire. Cast iron emerged as a structural material during the Industrial Revolution, first used prominently in the Iron Bridge at Coalbrookdale, England, completed in 1779. Wrought iron and later steel allowed far greater spans and heights. The Eiffel Tower, completed in 1889, demonstrated the structural possibilities of wrought iron at scale and influenced the development of steel-frame skyscraper construction in Chicago and New York. Reinforced concrete was systematically developed by Joseph Monier, a French gardener, who patented iron-reinforced concrete pots and panels in the 1860s, and later by engineers including François Hennebique who created the first comprehensive reinforced concrete framing system in the 1890s. The 1906 San Francisco earthquake caused widespread devastation and galvanized the engineering profession to develop seismic design provisions. Subsequent earthquakes — including the 1971 San Fernando and 1994 Northridge events — drove successive improvements in seismic codes, base isolation technology, and ductile detailing of reinforced concrete and steel frames. Building codes became increasingly standardized in the twentieth century, with the International Building Code (IBC) first published in 2000 providing a unified model code adopted across much of the United States. Building Information Modeling (BIM) emerged in the 2000s as a digital workflow integrating architectural, structural, and MEP design into a unified three-dimensional model, fundamentally changing coordination practices across the industry.
Frequently Asked Questions
Formula
Mortar Volume = Bricks x (Bed Joint Volume + Head Joint Volume); Bricks = Wall Area / (Brick Module Area)
The number of bricks is calculated from the wall area divided by the area of one brick module (brick plus joint). Mortar volume per brick includes horizontal bed joints and vertical head joints. Material quantities are derived from the mortar type mix ratio applied to total mortar volume.
Worked Examples
Example 1: Standard Residential Brick Wall
Problem: Calculate mortar needed for a 20 ft x 8 ft single-wythe brick wall using standard bricks (8 x 2.25 inches) with 3/8 inch joints and Type N mortar. Assume 10% waste.
Solution: Wall area: 20 x 8 = 160 sq ft\nBrick module: (8 + 0.375)/12 x (2.25 + 0.375)/12 = 0.698 x 0.219 = 0.153 sq ft\nBricks/sq ft: 1/0.153 = 6.54\nBricks with waste: ceil(6.54 x 160 x 1.10) = 1,151 bricks\nMortar per brick: ~0.0072 cu ft\nTotal mortar: ~8.3 cu ft\nType N mix (1:1:6): ~1 bag cement, ~1 bag lime, ~6.2 cu ft sand
Result: 1,151 bricks | ~8.3 cu ft mortar | ~96 bags premixed (80 lb) | Type N general purpose
Example 2: Garden Retaining Wall
Problem: A 12 ft x 4 ft retaining wall using Type S mortar with the same brick dimensions and 3/8 inch joints. 15% waste factor.
Solution: Wall area: 12 x 4 = 48 sq ft\nBricks/sq ft: 6.54\nBricks with waste: ceil(6.54 x 48 x 1.15) = 361 bricks\nMortar volume: ~2.6 cu ft\nType S mix (1:0.5:4.5): higher cement content for structural strength\nPremixed bags: ceil(361/12) = 31 bags
Result: 361 bricks | ~2.6 cu ft mortar | 31 bags premixed | Type S for structural retaining
Frequently Asked Questions
What are the different types of mortar and when should each be used?
There are four main types of mortar designated by ASTM C270, each with different compressive strengths and applications. Type M mortar has the highest strength at 2,500 PSI minimum and is used for below-grade applications, foundations, retaining walls, and structures subject to high lateral loads. Type S mortar has 1,800 PSI strength and is the most versatile high-strength option, suitable for below-grade work, areas with high wind or seismic activity, and structural applications. Type N mortar at 750 PSI is the general-purpose mortar used for most above-grade exterior and interior load-bearing walls, and is the most commonly specified type for residential construction. Type O mortar at 350 PSI is the weakest and used only for interior non-load-bearing walls and repair of existing mortar joints.
How much mortar do I need per square foot of brick wall?
The amount of mortar needed per square foot of brick wall depends on brick size, joint thickness, and wall configuration. For standard modular bricks (7-5/8 by 2-1/4 by 3-5/8 inches) with 3/8-inch mortar joints in a single wythe (one brick thick) wall, you need approximately 6.75 to 7 bricks per square foot, and roughly 0.006 to 0.008 cubic feet of mortar per brick. This translates to about 0.04 to 0.055 cubic feet of mortar per square foot of wall. For a double wythe wall, double these quantities. In practical terms, one 80-pound bag of premixed mortar covers about 12 to 14 standard bricks. Always add 10 to 15 percent for waste, as mortar that falls off during application, sticks to tools, or dries in the mixing container cannot be reused.
What is the correct mortar mix ratio for each type?
Mortar mix ratios are specified by volume of Portland cement to hydrated lime to sand. Type M uses a 1:0.25:3.375 ratio (1 part cement, one-quarter part lime, 3-3/8 parts sand), producing the strongest and least workable mix. Type S uses 1:0.5:4.5 (1 part cement, half part lime, 4.5 parts sand), offering good strength with better workability. Type N uses 1:1:6 (equal parts cement and lime, 6 parts sand), providing excellent workability and good water resistance for general use. Type O uses 1:2:9 (1 part cement, 2 parts lime, 9 parts sand), the most workable but weakest mix. The lime improves workability, water retention, and self-healing properties. Sand should be well-graded masonry sand, not sharp concrete sand, and should be damp but not wet for accurate volume measurement.
How do I properly mix and apply mortar for brickwork?
Proper mortar mixing begins with adding about three-quarters of the required water to a clean mixer or mixing tub. Add half the sand, then all the cement and lime, then the remaining sand and water. Mix for 3 to 5 minutes until the mortar reaches a smooth, butter-like consistency that holds its shape on a trowel but is workable enough to spread easily. The mortar should be stiff enough to support a brick but plastic enough to create full, even joints. Apply mortar to the bed joint with a trowel, then butter the head (end) of each brick before pressing it into place. Joints should be completely filled with no voids. Tool the joints when the mortar is thumbprint-firm, typically 20 to 30 minutes after placement. Mortar has a usable life of about 2 to 2.5 hours and should never be retempered with water more than once.
What factors affect mortar joint thickness and spacing?
Standard mortar joint thickness is 3/8 inch (10mm) for most brickwork, but this can vary based on several factors. Building codes typically require joints between 1/4 inch and 1/2 inch. Thicker joints (1/2 inch) provide more flexibility and better accommodate brick dimensional variations but reduce wall strength and weather resistance. Thinner joints (1/4 inch) are stronger and more weather-resistant but require more precisely sized bricks. Joint profile affects durability as well. Concave and V-shaped joints provide the best weather resistance by compressing the mortar and shedding water. Raked or flush joints look appealing but expose more mortar surface to weathering. Environmental conditions also matter. Hot, dry, or windy weather requires dampening bricks before laying and protecting fresh mortar from rapid drying, which causes cracking and weak bonds.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.
References
Reviewed by Abdullah, Technical Content Specialist · Editorial policy