Free estimate — verify against local code before building
Mortar Calculator
Select a brick or block, enter wall dimensions and joint size, and get mortar bags and cost.
What this calculator includes
Estimate mortar for a brick or concrete masonry wall from wall area, actual unit dimensions, joint thickness, and the unit coverage on the bag. Manufacturer coverage is visible and editable, while the geometry still reports an approximate mortar volume.
How to use this mortar calculator
- 01
Measure gross wall area
Enter wall length and height. Calculate major openings separately and deduct them only when the layout will actually save full units and mortar.
- 02
Match the masonry unit
Choose the closest actual brick or block dimensions; nominal block sizes include the joint and are not the solid unit dimensions.
- 03
Enter the joint and coverage
Use the specified joint thickness and the bricks-or-blocks-per-bag coverage printed on the chosen mortar product.
- 04
Add field allowance
Allow for droppings, tooling, unit absorption, mixing loss, bond pattern, and workmanship, then round up to whole bags.
Worked example
Example: 20 x 8 ft modular-brick wall
A 160 ft2 wall at a 3/8-inch joint contains about 1,098 modular bricks. Adding 10% field allowance gives about 1,208 unit placements; at 37 bricks per 80 lb bag, the purchase quantity rounds up to 33 bags.
Practical buying and overage guidance
Confirm mortar type, color, sand or preblended format, product coverage, storage, and batch consistency with the project documents and supplier. Keep bags dry and avoid mixing assumptions from different products.
Calculation sources and review
Primary references and formula assumptions are linked so you can verify them against the selected product, supplier, and adopted local requirements.
Internal formula review completed July 13, 2026. What this review covers
- Brick Industry Association - Technical Notes (opens in a new tab)
Brick masonry dimensions, joints, materials, and construction guidance.
- NCMA - Concrete Masonry Resources (opens in a new tab)
Concrete masonry construction and material references.
- QUIKRETE Mortar Mix data sheet (opens in a new tab)
Approximate standard-brick and 8 x 8 x 16 block coverage by bag size at a 3/8-inch joint.
- Sakrete Mortar Mix Type S (opens in a new tab)
Manufacturer unit-coverage guidance; verify the selected product and mortar type.
Frequently asked questions
How does joint thickness change mortar quantity?
A thicker bed or head joint increases the space between units, so mortar use rises. Use the joint specified for the project.
Should I use nominal or actual block dimensions?
Use the matching option based on actual unit dimensions. A nominal 8 x 8 x 16 block is typically about 7 5/8 x 7 5/8 x 15 5/8 inches before the joint.
Does this calculator subtract doors and windows?
Not automatically. For large openings, calculate their area separately and consider extra mortar and cuts around jambs, sills, lintels, returns, and bond changes.
Which mortar type should I buy?
Mortar type depends on the masonry, exposure, structural requirements, and project documents. This tool estimates quantity only and does not select Type M, S, N, or O.
Why is units-per-bag coverage editable?
Coverage varies by product, unit shape, joint profile, and workmanship. Enter the bricks-or-blocks-per-bag value stated by the manufacturer for the exact mortar mix.