Mortar Calculator
Estimate how much mortar you need for bricks or blocks, in bags of premixed mortar or as cement, lime and sand for a Type M, S, N or O mix.
- Mortar volume
- Or mix your own
- Portland cement
- Hydrated lime
- Masonry sand
- Mix Ratio
Job List
Jobs you add are saved in this browser.
| Job | Laying | Type | Bags (80 lb) | Cement | Lime | Sand | Remove |
|---|
How to Estimate Mortar
For premixed mortar, count units per bag. Quikrete's data sheet says an 80 lb bag of its Mortar Mix lays up to 37 standard bricks or 13 standard 8×8×16 blocks. For bricks, the calculator also works out the mortar volume from the joints: each brick sits on a bed joint and has a head joint at one end.
To mix your own, the parts are measured by volume. Sand makes up nearly all of the finished volume, because the cement and lime fill the spaces between sand grains, so a common estimate is one cubic foot of sand per cubic foot of mortar. ASTM C270, the standard for masonry mortar, uses these weights for measuring: portland cement 94 lb per cubic foot (one bag), hydrated lime 40 lb per cubic foot, and loose sand 80 lb per cubic foot.
Worked Example
Mortar Types
| Type | Cement : Lime : Sand | Typical Use |
|---|---|---|
| M | 1 : ¼ : 3¾ | Highest strength: below grade, foundations, retaining walls |
| S | 1 : ½ : 4½ | Strong: structural walls, below grade, patios |
| N | 1 : 1 : 6 | General purpose: above-grade walls and veneer |
| O | 1 : 2 : 9 | Low strength: interior, non-load-bearing, repointing soft brick |
Proportions by volume, with sand at three times the combined cement and lime, the top of ASTM C270's allowed range of 2¼ to 3 times.
Tips for Mixing Mortar
Mix only what you can use in about two hours, and retemper stiff mortar with a little water only in the first part of that time. Stronger isn't always better: mortar should be weaker than the brick so cracks form in the joints, which are easy to repoint. Type N suits most above-grade brick; use S or M where the wall is below grade or carries heavy loads.