Mortar Calculator
Estimate mortar needed for brick, block, and stone masonry.
Mortar Calculator
Use the measurement fields above to calculate your results instantly.
What This Calculator Does
The Mortar Calculator estimates how much mortar mix you need for brick, concrete block, stone veneer, and tuckpointing projects. Enter the number of masonry units or the wall area, and the calculator returns the required cubic feet of mortar, number of 60 lb and 80 lb bags, and the estimated mortar type for your application.
Mortar is the bonding material used between bricks, concrete blocks, and natural stone. It provides structural integrity, weather resistance, and a finished appearance to masonry walls, chimneys, and veneers. The quantity of mortar depends on the unit size (brick, block, or stone), joint thickness (typically 3/8 inch), and the total wall area. Mortar calculations vary significantly between projects - a brick wall requires roughly 0.02 cu ft of mortar per brick, while a concrete block wall needs about 0.04 cu ft per block.
Getting the mortar estimate right prevents material shortages that can delay a masonry project and avoids the cost of unused bags. Use this calculator as a planning estimate before purchasing materials from your local supplier.
How to Use
- Count or estimate the number of masonry units in your wall. For bricks, count the actual unit quantity. For walls, multiply the length by the height in feet, then multiply by the units per sq ft (6.75 for standard modular brick, 1.125 for 8x8x16 block).
- Select the masonry unit type from the options above - modular brick, queen brick, 8x8x16 CMU block, or stone veneer.
- Select your mortar type (Type N, Type S, or Type M) for the calculator to use the appropriate mix ratio.
- Enter the total unit count into the calculator.
- The calculator applies standard mortar coverage rates per unit and includes a 10% waste factor. Increase to 15-20% for stone veneer or repair work.
How to Calculate Mortar
Calculating mortar quantity requires determining the volume of mortar joints based on the unit size, joint thickness, and number of units.
Step 1: Determine the Number of Masonry Units
For standard modular brick (2.25 x 3.75 x 8 inches): approximately 6.75 bricks per sq ft of wall including 3/8 inch mortar joints. For 8x8x16 concrete blocks: approximately 1.125 blocks per sq ft. For queen brick (2.75 x 3 x 9 inches): approximately 5.5 bricks per sq ft. To find the total: Total Units = Wall Area (sq ft) x Units per Sq Ft.
Step 2: Calculate Mortar Volume Per Unit
Each standard modular brick requires approximately 0.02 cu ft of mortar with a 3/8 inch joint (this includes the bed joint and head joint). Each 8x8x16 CMU block requires approximately 0.04 cu ft of mortar. For stone veneer, the volume ranges from 0.05-0.10 cu ft per sq ft depending on stone depth and joint width. Total Mortar Volume = Unit Count x Mortar per Unit.
Step 3: Convert to Bags
An 80 lb bag of pre-mixed mortar yields approximately 0.7 cu ft of mixed mortar. A 60 lb bag yields approximately 0.5 cu ft. To find the number of bags: Bags = Mortar Volume / Bag Yield. Round up to the nearest full bag.
Step 4: Apply Waste Factor
Multiply the bag count by (1 + waste percentage). For standard walls: 10%. For stone veneer or tuckpointing: 15-20%. For small repair jobs with irregular joints: 20%. Waste accounts for mortar that falls off the trowel, buttering waste, leftover mortar in the mixer, and spillage.
Practical Measurement Tips
- Mix in manageable batches. Mortar has a working time of 2-2.5 hours depending on temperature and humidity. On hot days (above 90F), working time drops to 1-1.5 hours. Mix only what you can use in that window. A batch from one 80 lb bag with appropriate water takes about 30-45 minutes to use for an experienced mason.
- Keep mortar off brick faces. Mortar stains on brick are difficult to remove, especially on smooth-faced or glazed brick. Use a mason trowel to apply mortar cleanly. Clean any mortar spills on brick faces within 30 minutes using a dry brush - do not use water, which can smear the stain.
- Use the right mortar type for the job. Type N is the general-purpose mortar for above-grade walls, chimneys, and veneers. Type S is stronger and should be used for below-grade walls, retaining walls, and load-bearing applications. Type M is the highest strength, used for heavy-load foundations and manholes. Never use Type N where Type S is specified - it can lead to structural failure.
- Check mortar consistency. Proper mortar should hold its shape on the trowel without slumping but should spread easily. Add water gradually - too much water weakens the bond. The pre-mixed bag label will specify the water range for that specific mix. Use clean, potable water - dirty water can affect the cure and bond strength.
- Plan for tuckpointing and repairs separately. Tuckpointing (replacing deteriorated mortar joints) uses significantly less mortar per linear foot than new construction because the joint depth is only 1/2 to 3/4 inch versus the full 3.75 inch depth of a brick joint. For tuckpointing, estimate approximately 0.005 cu ft of mortar per linear foot of joint for a 3/8 x 3/4 inch joint.
Worked Examples
Brick Wall Section
A 10 ft long, 6 ft high garden wall using standard modular brick, 3/8 inch joints, Type N mortar.
- →Calculate wall area: 10 ft x 6 ft = 60 sq ft.
- →Standard modular brick: 6.75 bricks per sq ft. Total bricks: 60 x 6.75 = 405 bricks.
- →Each brick needs 0.02 cu ft of mortar. Base mortar volume: 405 x 0.02 = 8.1 cu ft.
- →An 80 lb bag yields 0.7 cu ft. Base bags: 8.1 / 0.7 = 11.6 bags. Add 10% waste: 11.6 x 1.10 = 12.8 bags. Round up to 13 bags.
Result: 13 bags of 80 lb Type N mortar mix for a 60 sq ft modular brick wall (405 bricks).
For brick walls that will be exposed to view, consider using Type N mortar with a color pigment for a finished appearance. White mortar with red brick creates a classic contrast. Always build a small test panel first to confirm the mortar color and joint profile match your expectations.
Concrete Block Retaining Wall
A 24 ft long, 3 ft high retaining wall using 8x8x16 standard CMU blocks, Type S mortar.
- →Calculate wall area: 24 ft x 3 ft = 72 sq ft.
- →Standard 8x8x16 block: 1.125 blocks per sq ft. Total blocks: 72 x 1.125 = 81 blocks.
- →Each block needs 0.04 cu ft of mortar. Base mortar volume: 81 x 0.04 = 3.24 cu ft.
- →An 80 lb bag yields 0.7 cu ft. Base bags: 3.24 / 0.7 = 4.6 bags. Add 10% waste: 4.6 x 1.10 = 5.1 bags. Round up to 6 bags.
Result: 6 bags of 80 lb Type S mortar mix for a 72 sq ft block retaining wall (81 blocks).
Type S mortar is required for retaining walls because it has higher compressive strength and better resistance to soil pressure and moisture. Ensure the wall has proper drainage behind it (gravel backfill and weep pipes) to reduce hydrostatic pressure on the mortar joints.
Tuckpointing and Repair Job
Repointing a 200 sq ft brick chimney with deteriorated mortar joints, using Type N mortar mix.
- →Estimate the total linear feet of joints. For modular brick at 6.75 bricks per sq ft: approximately 15 linear ft of joint per sq ft. Total: 200 x 15 = 3,000 linear ft.
- →Tuckpointing joints are 3/8 in wide x 3/4 in deep. Mortar volume per linear ft: (0.375/12) x (0.75/12) x 1 = 0.00195 cu ft per linear ft.
- →Total mortar volume: 3,000 x 0.00195 = 5.85 cu ft.
- →A 60 lb bag yields 0.5 cu ft. Base bags: 5.85 / 0.5 = 11.7 bags. Add 20% waste for a repair job: 11.7 x 1.20 = 14 bags.
Result: 14 bags of 60 lb Type N mortar mix for repointing a 200 sq ft brick chimney.
Tuckpointing requires a mortar that is slightly weaker than the original brick to prevent damage - the mortar should fail before the brick does. Type N mortar is typically appropriate for repointing older brick chimneys. For historic homes, consider using a Type O lime-based mortar that matches the original formulation.
Stone Veneer Project
Installing 150 sq ft of natural stone veneer on a fireplace wall using Type S mortar mix.
- →Stone veneer varies in thickness. Estimate mortar volume at 0.08 cu ft per sq ft for 3-inch deep stone.
- →Total mortar volume: 150 x 0.08 = 12 cu ft.
- →An 80 lb bag yields 0.7 cu ft. Base bags: 12 / 0.7 = 17.1 bags. Round up to 18 bags.
- →Add 20% waste for stone veneer (irregular shapes, buttering, and mortar squeeze-out): 18 x 1.20 = 21.6 bags. Round up to 22 bags.
Result: 22 bags of 80 lb Type S mortar mix for a 150 sq ft stone veneer installation.
Stone veneer requires a thicker mortar bed and more waste than brick or block work because each stone has an irregular shape that needs individual fitting. Use a scratch coat on the wall surface before applying stone veneer. For ledger panels, use a specially formulated stone veneer mortar that provides extra adhesion and longer working time.
Waste Factors by Material
Always order more than your exact calculated quantity. Material suppliers typically do not accept returns on cut or opened materials. The waste factor accounts for cuts at walls, corners, defects, and installation error.
| Project Type | Waste Factor | Notes | Related Tool |
|---|---|---|---|
| Simple straight wall (brick or block) | 10% | Minimal cutting; standard joints; consistent unit sizes | Brick Calculator |
| Small repair / tuckpointing | 15-20% | Irregular joints; mortar waste from removing old material | Mortar Calculator |
| Stone veneer installation | 15-20% | Irregular stone shapes increase buttering waste | Concrete Block Calculator |
| Irregular / rustic joints | 20% | Wide and inconsistent joints require more mortar and generate more waste | Mortar Calculator |
| Pilasters and columns | 15% | More cuts and complex joint patterns around corners | Concrete Calculator |
Square Footage by Project Type
| Project | What to Measure | Unit | Key Note | Related Tool |
|---|---|---|---|---|
| Brick wall (above grade) | Wall length x height in feet | Number of bricks | 6.75 modular bricks per sq ft; Type N mortar for non-load-bearing walls | Brick Calculator |
| Concrete block wall (retaining) | Wall length x height in feet | Number of blocks | 1.125 blocks per sq ft; Type S mortar for below-grade and retaining walls | Concrete Block Calculator |
| Tuckpointing / repointing | Wall area in sq ft or linear ft of joints | Cubic feet of mortar | Use Type N or Type O mortar; match original mortar strength for historic work | Brick Calculator |
| Stone veneer | Wall area in sq ft | Square feet | Estimate 0.08 cu ft mortar per sq ft; use Type S or stone veneer mortar | Concrete Calculator |
| Chimney construction | Number of bricks (approx. 60-80 bricks per vertical ft) | Number of bricks | High-heat areas may require refractory mortar; standard Type N for exterior brick | Brick Calculator |
| Masonry pillar or column | Perimeter and height in feet | Number of bricks or blocks | Calculate corner bricks separately; corners need more mortar for full buttering | Concrete Block Calculator |
Reference Table
| Masonry Unit | Qty | Mortar Volume | 80 lb Bags | 60 lb Bags |
|---|---|---|---|---|
| Modular Brick | 500 | 10 cu ft | 14 bags | 18 bags |
| Modular Brick | 1,000 | 20 cu ft | 27 bags | 36 bags |
| 8x8x16 Block | 100 | 4 cu ft | 6 bags | 8 bags |
| 8x8x16 Block | 200 | 8 cu ft | 11 bags | 14 bags |
| Queen Brick | 500 | 12 cu ft | 16 bags | 21 bags |
How We Calculate
Core Formula
The mortar calculator uses unit-based volume estimation. Each masonry unit type has a standard mortar volume per unit derived from the unit dimensions and the nominal joint thickness (3/8 inch). The formula is: Total Mortar Volume (cu ft) = Unit Count x Mortar Volume per Unit. For modular brick at 3/8 inch joints: 0.02 cu ft per brick. For 8x8x16 CMU: 0.04 cu ft per block. For stone veneer: 0.05-0.10 cu ft per sq ft depending on stone depth.
Mortar Coverage Assumptions
The calculator applies standard coverage rates used by the Masonry Contractors Association of America and the Brick Industry Association. Coverage assumes full bed and head joints for all units. For brick, both the horizontal bed joint and vertical head joint are included. For block, the calculator assumes face-shell bedding (mortar applied to the outer edges only) which is standard for concrete block construction in the US. Full-bed bedding (mortar applied across the entire block width) would require approximately 50% more mortar.
Bag Yield Conversion
Pre-mixed mortar bag yields are based on manufacturer specifications. An 80 lb bag of Type N or Type S mortar mix yields approximately 0.7 cu ft of mixed mortar when the recommended amount of water is added. The calculator divides the total mortar volume by the bag yield and applies the waste multiplier. Bag yields vary slightly between manufacturers - check the label on your specific brand for the exact coverage per bag.
Waste Factor Application
Waste factors account for mortar that falls off the trowel during application, buttering waste on each unit, leftover mortar in the mixing pan or wheelbarrow, and mortar that hardens before it can be used. The 10% baseline waste factor is standard for new construction with consistent unit sizes. The 15-20% factors for repair and stone work reflect the additional waste inherent in irregular units and partial joint removal.
References and Data Sources
Masonry Contractors Association of America (MCAA) - Mortar Estimating Guide
The MCAA provides the standard method for estimating mortar quantities in brick, block, and stone construction. Their guide includes mortar volume per unit for all standard masonry unit types, joint thickness adjustments, and waste factor recommendations used by professional masons across North America. Masonry Contractors Association of America, 2025 Edition, www.masonrycontractors.org.
Brick Industry Association (BIA) - Technical Notes on Brick Construction
The BIA publishes comprehensive technical guidance on brick masonry, including mortar mix specifications (Technical Note 8), mortar joint design, and material estimating methods. Their coverage rates for modular brick are the industry standard used by architects and contractors. Brick Industry Association, 2025, www.gobrick.com.
ASTM C270 - Standard Specification for Mortar for Unit Masonry
Defines the physical property requirements for Types N, S, M, O, and K mortar used in masonry construction. This standard specifies the minimum compressive strength, water retention, and air content for each mortar type. Type N (750 psi), Type S (1,800 psi), and Type M (2,500 psi) are the most common classifications for residential masonry.
International Residential Code (IRC) - Chapter 6: Wall Construction
Establishes minimum requirements for masonry wall construction, including mortar type requirements by wall type and location, reinforcement requirements, and foundation attachment. The IRC specifies which mortar types are acceptable for various applications and sets minimum wall thickness standards.
All references are used for general estimation guidance only. BuildCalcHub does not claim certification, endorsement, or partnership with any listed organization. Always consult a licensed professional for your specific project requirements.
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