Free Mortar Mix Calculator — Bags & Coverage (2026)

How to Use This Calculator

1. 1Calculate the total wall or surface area in square feet — multiply wall length by height, then subtract window and door openings.
2. 2Select your mortar type — Type N for general above-grade work, Type S for structural and below-grade, Type M for heavy loads and foundations.
3. 3Choose the joint thickness — 3/8" is the standard for most block and brick work.
4. 4Click Calculate to get the number of pre-mixed bags needed plus quantities for mixing from scratch with portland cement and sand.

About This Material

Mortar is the bonding material used between blocks, bricks, and stone units in masonry construction. It is composed of portland cement, hydrated lime, sand, and water, mixed to a workable consistency that allows masons to lay units efficiently while providing structural bond and weather resistance. The three most common mortar types are Type N, Type S, and Type M, classified by ASTM C270. Type N (750 psi compressive strength) is the most widely used general-purpose mortar for above-grade walls, chimneys, and non-load-bearing partitions. It offers the best balance of workability, bond strength, and flexibility. Type S (1,800 psi) is required for structural walls, below-grade foundation walls, retaining walls, and any masonry in contact with soil. Type M (2,500 psi) provides the highest compressive strength and is used for heavy-load foundations, retaining walls below grade, and masonry subjected to extreme lateral pressure. Pre-mixed mortar (such as Quikrete or Sakrete) comes in 60 lb and 80 lb bags. A 60 lb bag yields approximately 0.5 cubic feet of mortar and covers roughly 14 standard blocks (8x8x16) at 3/8-inch joints. An 80 lb bag yields about 0.667 cubic feet. For large projects, mixing from scratch with portland cement, hydrated lime, and masonry sand is more economical — a Type N batch uses 1 part cement, 1 part lime, and 6 parts sand by volume. Mortar joint thickness affects both appearance and material usage significantly. The standard 3/8-inch joint is the baseline for most residential masonry. Thicker joints (1/2 to 3/4 inch) use 30 to 100% more mortar but provide better accommodation for irregularly sized stone or salvaged brick. Thinner joints (1/4 inch) reduce mortar use by about 30% and are common with precision-cut stone veneer.

Installation Tips

• •Mix only as much mortar as you can use within 90 minutes — mortar begins to set and loses workability after that window.
• •Dampen blocks or bricks before laying to prevent them from absorbing water from the mortar, which causes weak bonds.
• •Maintain consistent joint thickness by using a mason's line and checking courses with a level every 3 to 4 rows.
• •Tool (strike) the joints when the mortar is thumbprint-firm — tooling too early smears the surface, and too late prevents proper compaction.
• •Cover freshly laid masonry with plastic sheeting in hot, dry, or windy conditions to prevent rapid moisture loss and cracking.

Common Mistakes to Avoid

• ⚠Using the wrong mortar type — Type M in above-grade walls is too rigid and cracks; Type N below grade is too weak and deteriorates.
• ⚠Adding too much water to the mix — soupy mortar has reduced strength and stains the face of the blocks or bricks.
• ⚠Re-tempering mortar after it has begun to set — adding water to stiffened mortar restores workability but permanently reduces bond strength.
• ⚠Mixing too large a batch — mortar that sits in the wheelbarrow for over 2 hours is dead and must be discarded, wasting material.
• ⚠Not buttering the ends of blocks or bricks — head joints left empty create water entry points and weaken the wall structurally.

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