Mortar Calculator
Calculate the volume of wet mortar and number of 80 lb or 60 lb pre-mix bags required for laying brick, CMU block, or stone masonry walls.
Calculation Results
Calculated wet volume of mortar paste needed to bed and head all joints.
Standard 80 lb bags of pre-blended dry mortar mix (yields 0.85 cu ft wet paste each).
Standard 60 lb bags of pre-blended dry mortar mix (yields 0.64 cu ft wet paste each).
Sacks of pure masonry cement if blending on-site with bulk builder sand (1 sack per 3 cu ft mortar).
Clean damp masonry sand required for site mixing.
How This Calculator Works
Estimate your mortar materials quickly:
- Select Method: Choose whether you want to calculate by total wall surface area or by a known count of bricks and blocks.
- Select Mortar Type: Type N for general above-ground walls; Type S for below-grade foundations or structural block walls.
- Include Trowel Waste (15%): Masonry involves significant mortar "droppings" that fall during joint striking and trowel work. 15% is recommended for DIY projects.
- Choose Purchase Packaging: The calculator provides both retail pre-mixed bag quantities (80lb and 60lb) and site-mixed raw ingredients (cement sacks and sand tons).
Formula & Calculations
Mortar volume requirements depend on joint thickness (standard 3/8-inch) and unit geometry following ASTM C270 specifications:
1. Standard Unit Consumption Rates
- Standard Modular Bricks: Laying 1,000 bricks requires approximately 7.0 cubic feet of wet mortar (approx. 8.5 eighty-pound bags).
- CMU Blocks (8x8x16): Laying 100 concrete blocks requires approximately 3.6 cubic feet of wet mortar (approx. 4.2 eighty-pound bags).
2. Pre-Mixed Bag Yields
- 80 lb bag of Mortar Mix: Yields
0.85 cubic feetof mixed wet paste. - 60 lb bag of Mortar Mix: Yields
0.64 cubic feetof mixed wet paste.
3. ASTM C270 Mortar Types
- Type N (750 PSI): General exterior and interior walls above grade. Maximum workability and weather resistance.
- Type S (1,800 PSI): Below grade foundations, structural retaining walls, sewers, and high-seismic zones. High flexural bond strength.
- Type M (2,500 PSI): Heavy load-bearing columns, stone foundations, and pavement retaining curbs.
- Type O (350 PSI): Non-load bearing interior restoration and tuckpointing historic soft masonry.
Step-by-Step Calculation Examples
Brick Facade Wall (25ft long x 8ft high)
Laying a residential brick wall with standard modular bricks and a 15% trowel waste buffer.
- calc_mode: wall_dims
- masonry_type: brick
- wall_length: 25
- wall_height: 8
- mortar_type: N
- waste: 15
- mortar_volume: 11.27 cu ft
- bags_80lb: 14
- bags_60lb: 18
- masonry_cement_bags: 4
Frequently Asked Questions
How many bags of mortar do I need for 1,000 bricks?
For 1,000 standard modular bricks laid with 3/8-inch joints, you will need approximately 7.0 cubic feet of wet mortar. With a 10% to 15% waste allowance, purchase nine to ten 80 lb bags of pre-mixed mortar mix.
How many bags of mortar do I need for 100 cinder blocks?
Laying 100 standard 8x8x16 concrete masonry blocks requires approximately 3.6 cubic feet of mortar, which equals 4.5 bags. Purchase 5 eighty-pound bags of Type S mortar mix.
What is the difference between Type N and Type S mortar?
Type N mortar has a minimum compressive strength of 750 PSI and is designed for general above-grade exterior walls and chimneys. Type S has a minimum strength of 1,800 PSI, designed for severe lateral loads, below-grade foundations, and retaining walls.
What is the recipe for site-mixed mortar?
Standard ASTM C270 Type N site-mix mortar uses 1 part masonry cement to 2-1/4 to 3 parts clean damp masonry sand by volume, with enough clean water to achieve a workable, plastic consistency.
Can I use concrete mix instead of mortar for bricks?
No. Concrete contains coarse gravel rocks and aggregate that make it impossible to achieve a clean, level 3/8-inch joint. Mortar contains only fine sand and cementitious binders formulated specifically to adhere to masonry units.
How long can mixed mortar sit in the wheelbarrow before it goes bad?
Mixed mortar should typically be placed within 1.5 to 2 hours in moderate weather. If it begins to stiffen due to water evaporation, it may be "re-tempered" once by adding a small amount of water. Never re-temper mortar that has begun its chemical initial set after 2 hours.