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Mortar Mix Calculator

Bags of mortar mix for a brick or block wall, or thinset tile mortar by trowel size.

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Mortar needed

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Mix only what you can use in about 90 minutes

Masonry mortar stiffens as it sits, and adding water after the first mix (retempering) weakens it if you overdo it. Mix a partial bag at a time on hot or windy days. Thinset has a similar pot life, listed on the bag, and should never be retempered with extra water once it starts to set.

How much mortar mix brick, block and tile need

This mortar mix calculator estimates the bags of mortar mix needed per square foot of brick, block or tile coverage. Pick what you are laying, enter the area of the wall or floor, and it converts that area into units and then into bags.

For masonry walls it counts units first: about 6.75 modular bricks per sq ft or 1.125 standard 8 × 16 in. blocks per sq ft, both with 3/8 in. joints. QUIKRETE's Mortar Mix data sheet says one 80 lb bag lays up to 37 standard bricks or 13 standard blocks, so bags = units × (1 + extra %) ÷ units per bag. Type N mortar suits most above-grade walls; Type S is the usual choice below grade and for retaining walls.

Tile is set with thinset mortar, which is figured by trowel size instead of by unit. MAPEI lists coverage for a 50 lb bag at roughly 80 to 100 sq ft with a 1/4 × 1/4 in. square notch, 60 to 80 sq ft with 1/4 × 3/8 in., and 40 to 50 sq ft with 1/2 × 1/2 in. The calculator uses the middle of each range. Larger tiles need a bigger notch to get full coverage on the back of the tile.

Where these numbers come from

The formulas and default values in this calculator are based on:

  • QUIKRETE Mortar Mix No. 1102 data sheet (80 lb bag lays up to 37 bricks or 13 blocks)
  • MAPEI thinset coverage by trowel size
  • Brick Industry Association modular brick dimensions

These are planning estimates. Check product labels, your local building code, and a licensed contractor before you buy materials or build.

Frequently asked questions

What's the difference between mortar mix and concrete mix?

Mortar mix is cement, lime and fine sand, made to bond bricks and blocks together. Concrete mix adds gravel for strength in slabs, footings and posts. They aren't interchangeable; use the concrete calculator for pours.

Why does tile use thinset instead of regular mortar?

Thinset is a polymer-modified cement adhesive spread in a thin, notched layer. It bonds tile to backer board or concrete with much less material than a bed of masonry mortar, and it holds up to the moisture and movement a floor sees.

Is 10% extra enough?

For most walls, yes. Add more if you are new to laying block or brick, working in hot weather where mortar stiffens quickly, or back-buttering large tiles, which uses noticeably more thinset.

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