This mortar calculator estimates premixed mortar bags for brick, block and stone masonry — from how many units you’re laying — with the coverage rates masons actually plan around.
Coverage Rates Are Masonry’s Exchange Rates
Industry planning figures (⅜” joints, standard units): one 60-lb bag of premix lays ≈ 35 standard blocks, ≈ 100 modular bricks, ≈ 45 oversize/veneer bricks, or ≈ 12 large stones. Unit counts come from our Brick Calculator and Concrete Block Calculator. Waste on masonry is structural to the process — boards, droppings, retempering losses — hence the 15% built into this tool’s answer. Part of our Construction Calculators collection.
Worked Examples (Verified)
- 100 blocks (defaults): 100 ÷ 35 = 2.86 → × 1.15 → 4 bags (rounded up)
- 1,000 modular bricks: 10 bags exact → 12 with waste — the number a weekend chimney repoint surprises people with
- Repointing vs new work: repointing consumes by joint volume raked out, not by unit count — this calculator prices new laying; for repointing, a 60-lb bag typically covers ~15–25 ft² of brick wall at ¾” depth
- Joint size moves everything: ½” joints on block can raise consumption ~25% over the ⅜” standard; glass block and thin joints move it the other way
Type Matters More Than Quantity
- Type N (general, above-grade, ~750 psi): most residential walls and chimneys above the roofline.
- Type S (~1,800 psi): below grade, retaining, high lateral load.
- Type M (~2,500 psi): foundations and heavy load — too hard for soft historic brick (it spalls the units instead of sacrificially wearing itself).
- Retempering: mortar stiffening on the board gets one water remix within ~2.5 hours of mixing; beyond that it’s waste — counted in the 15%.
Related Tools
- Brick Calculator — bricks for the wall first
- Concrete Block Calculator — block counts with openings
- Construction Calculators — the full collection
Frequently Asked Questions
How many bags of mortar do I need for 100 blocks?
At the standard rate (≈ 35 blocks per 60-lb bag), 100 blocks need 2.9 bags — buy 4 with the customary 15% waste allowance. This calculator applies that rate and waste to any count and unit type.
How much area does one bag of mortar cover for brick?
Via units: a 60-lb bag lays ≈ 100 modular bricks, which face ≈ 15–16 ft² of wall in running bond (single wythe). Stone and oversize units cover less per bag — their joints are wider and deeper. The bag’s own yield is ≈ 0.45 ft³ of mixed mortar.
Mortar vs concrete — can I substitute?
No. Mortar is a bonding material (higher lime/workability, graded for joints); concrete is a structural material with coarse aggregate. Bags look alike; the mixes, strengths and purposes differ. Grout (for filling block cores) is a third product again — fluid by design.
What’s the difference between mortar types N, S and M?
Compressive strength and intended exposure: N ≈ 750 psi (general above-grade), S ≈ 1,800 (below-grade/lateral loads), M ≈ 2,500 (foundations). Stronger isn’t universally better — mortar should be weaker than the units it joins so it acts sacrificially; hard modern mortar destroys soft historic brick.
How much waste should I allow?
15% is the planning standard for premix bags (droppings, board loss, batch tails); beginners and intricate work warrant 20%. Unopened bags store dry for months — overbuying one bag beats a mid-wall supply run with a half-set mixer.
Is this mortar calculator free?
Yes — free, instant, no sign-up.