How much mortar do I need?
Mortar is easiest to estimate from the number of units you're laying. Enter bricks or blocks and the calculator gives both ways to buy it:
| Laying | Premixed 80 lb bags | Masonry cement + sand |
|---|---|---|
| 100 modular bricks | 3 | about 1 bag + 3 cu ft sand |
| 500 modular bricks | 15 | 4 bags + 12 cu ft sand |
| 1,000 modular bricks | 30 | 8 bags + 24 cu ft sand |
| 100 blocks (8×8×16) | 10 | — |
| 250 blocks | 23 | — |
Premixed bag counts include 10% for droppings and are based on QUIKRETE's rated yield of 37 bricks or 12 blocks per 80 lb bag. Masonry cement counts use the rule of thumb the Brick Industry Association quotes — eight bags lay 1,000 modular bricks — with about three cubic feet of damp sand per bag.
Premixed mortar mix or masonry cement?
Premixed mortar mix (cement, lime and sand in one bag) is the right call for most homeowner projects: a mailbox column, a garden wall, a repair. Every batch is consistent, and you only add water. It costs more per brick laid.
Masonry cement plus sand is what masons use on bigger jobs. A 1,000-brick wall needs 8 bags of cement and roughly 24 cubic feet — a bit over a ton — of mason sand. It's cheaper by the brick but you're measuring sand by the shovel, and color and strength vary if you're not consistent. For anything over a couple thousand bricks, it's worth it.
The theoretical volume of mortar in the joints is much smaller than either number: BIA's table puts it at 8.1 cubic feet per 1,000 modular bricks with 3/8 in joints. The gap between that and what you buy is droppings, the mortar left in the bucket at the end of a session and the extra that squeezes out of every joint.
Mortar mix calculator: Type N vs Type S
- Type N — the general-purpose mortar for above-grade brick and block that isn't holding back soil: garden walls, veneer, chimneys above the roof. Most bagged "mortar mix" is Type N.
- Type S — higher strength, for foundations, retaining walls, below-grade block and walls that take wind or soil pressure.
- Type M — the strongest, for heavy loads below grade; rarely needed on a house project.
Stronger isn't automatically better: a mortar much harder than the brick can cause the brick faces to crack and spall as the wall moves with temperature. Match the type to the job.
One common mix-up: thinset for tile is not masonry mortar. If you're setting tile, use the thinset calculator, which sizes bags by trowel notch. For laying units, start with the brick calculator or the concrete block calculator to get the count.
