Mortar Mix Ratio: Type N, S, and M Explained
Mortar mix ratio depends on the mortar type. Common proportions by volume are about 1 part portland cement, 1 part hydrated lime, and 6 parts sand for Type N, and about 1 part cement, 1/2 part lime, and 4.5 parts sand for Type S. Type M is stronger still at about 1 part cement, 1/4 part lime, and 3 parts sand. Bagged mortar mixes and masonry cement simplify this, and most homeowners use them instead of measuring lime separately.
Concrete calculator →Common mortar types
| Type | Approx. cement : lime : sand | Strength | Typical use |
|---|---|---|---|
| M | 1 : 1/4 : 3 | Highest | Below grade, heavy loads, retaining walls |
| S | 1 : 1/2 : 4.5 | High | Foundations, structural block, patios |
| N | 1 : 1 : 6 | Medium | Above-grade walls, general brickwork |
| O | 1 : 2 : 9 | Low | Interior, non-load-bearing, repointing soft brick |
Sand quantities are commonly given as a range, about 2.25 to 3 times the combined cement and lime volume. The ranges come from building standards such as ASTM C270.
Which type to choose
- Block foundation or retaining wall: Type S, or Type M in some designs.
- Above-grade brick or block wall: Type N is common.
- Brick patio or paver base set in mortar: Type S.
- Repointing old, soft brick: a softer lime-rich mortar, often Type N or O, so the mortar is weaker than the brick.
Stronger is not always better. Mortar that is harder than the masonry can cause the brick or stone itself to crack.
Bagged mixes and masonry cement
- Pre-blended mortar mix: just add water. Labeled by type (N or S).
- Masonry cement: cement and lime blended; mix about 1 part to 3 parts sand.
- Portland plus lime: mix your own for control on large jobs.
An 80-pound bag of pre-blended mortar typically lays only about 13 standard 8x8x16 blocks or about 40 bricks. A 70-pound bag of masonry cement mixed with sand goes much further, roughly 30 to 35 blocks or 125 to 140 bricks, because the sand is added on site. See how many bags of mortar per 100 blocks.
Mixing tips
- Add about three quarters of the water first.
- Add dry material and mix 3 to 5 minutes.
- Add water slowly until the mortar holds a ridge on the trowel without slumping.
- Use it within about 2 hours; retemper once with a little water if it stiffens early, then discard.
Mortar vs concrete
Mortar bonds units together and has no coarse aggregate. Concrete includes gravel and is used for structural slabs and footings. See concrete mix ratio for the comparison.
Bottom line
Typical mortar mix ratios are about 1:1:6 cement, lime, and sand for Type N, 1:1/2:4.5 for Type S, and 1:1/4:3 for Type M. Use Type S for foundations, patios, and below grade, Type N for most above-grade walls, and a softer mortar for repointing old brick.
Questions people ask
What is the mix ratio for Type S mortar?
About 1 part portland cement, 1/2 part hydrated lime, and 4.5 parts sand by volume.
What is the mix ratio for Type N mortar?
About 1 part portland cement, 1 part lime, and 6 parts sand by volume.
Which mortar should I use for a block foundation?
Type S is a common choice for foundations and below-grade block.
Can I use concrete mix instead of mortar?
No. Concrete mix has gravel and will not bed masonry units properly.
How long is mixed mortar good for?
About 2 hours in normal weather. Retemper once if needed, then discard.
Related guides
- Concrete Mix Ratio: Cement, Sand, Gravel, and Water
- How Many Bags of Mortar per 100 Blocks? Rule of Thumb
- Cinder Block vs Concrete Block: What the Names Mean
- Filling Concrete Block Cores: Grout, Rebar, and Volume
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