Mortar Calculator
Calculate how many bags of mortar mix you need to lay bricks or concrete blocks, based on the number of units, joint width and bag size, plus a site-mix estimate.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- 80 lb bags of mortar mix
- 15 bags
- 14.9 bags for 500 bricks including 10% waste
- Mixed mortar
- 10.5 cu ft
- 0.7 cu ft per bag
- Units per bag
- 37 bricks
- With 0.375 in joints
- Site mix alternative
- 5 bags masonry cement
- 70 lb (32 kg) bags of Type N masonry cement plus about 10.5 cu ft of masonry sand, mixed 1 : 2.25 by volume
Mortar formula
Units per bag = 37 bricks or 13 blocks per 80 lb bag (27 bricks or 10 blocks per 60 lb bag) x 0.375 / joint width (in)
Bags = Number of units x (1 + waste %) / Units per bag, rounded up
Mixed mortar (cu ft) = Bags x 0.70 (80 lb) or 0.53 (60 lb)
Site mix: sand (cu ft) = mixed mortar, masonry cement bags = sand / 2.25Worked example
300 standard blocks with 60 lb bags and 3/8 in joints: a 60 lb bag lays 10 blocks, so 300 x 1.1 / 10 = 33 bags, which mixes 33 x 0.53 = 17.5 cubic feet of mortar.
The same wall with 1/2 in joints: each bag now lays 10 x 0.375 / 0.5 = 7.5 blocks, so 330 / 7.5 = 44 bags. As a site mix, 17.5 cubic feet of sand and 17.5 / 2.25 = 8 bags of masonry cement cover the 3/8 in version.
Quick reference
| Units | 80 lb bags, brick | 80 lb bags, block | 60 lb bags, brick | 60 lb bags, block |
|---|---|---|---|---|
| 100 | 3 | 9 | 5 | 11 |
| 250 | 8 | 22 | 11 | 28 |
| 500 | 15 | 43 | 21 | 55 |
| 1,000 | 30 | 85 | 41 | 110 |
How to calculate mortar for brick and block
Manufacturers rate premixed mortar by how many units one bag lays with a standard 3/8 inch joint: about 37 modular bricks or 13 standard 8 x 8 x 16 blocks per 80 lb bag. Divide your unit count by that figure and add 10 percent for waste, which is real in masonry work: mortar falls off the trowel, dries on the board and gets scraped off the wall. In hot, windy weather the board dries faster and waste climbs; TMS 602 hot-weather rules start at 100 F, or 90 F with wind over 8 mph, and cap board life at 2 hours.
Joint width changes the count almost in proportion. A 1/2 inch joint uses about a third more mortar than a 3/8 inch joint. Block uses far more mortar per unit than brick but far less per square foot of wall, since a block covers the area of about six bricks with face-shell bedding only.
Premixed bags vs site mix
Premixed mortar in 60 or 80 lb bags needs only water and is the practical choice up to a few hundred bricks or a hundred blocks. Beyond that, buy masonry cement and sand separately. Type N masonry cement is mixed 1 part to 2-1/4 to 3 parts masonry sand by volume, one 70 lb bag to 2-1/2 to 3 cubic feet of sand. That makes 2-1/4 to 3 cubic feet of mortar, enough for 120 to 150 bricks or 40 to 55 blocks. Masonry sand (ASTM C144) is sold by the ton, about 1.3 tons to the yard, and 3/4 yard lays 1,000 brick. Most pits have a minimum delivery, so a small job is cheaper in bags even at three times the price per cubic foot.
Use Type N (ASTM C270, 750 psi) for brick veneer, chimneys and most above-grade work; it is softer than the brick, so movement cracks the joint and not the face. Type S (1,800 psi) goes in foundations, retaining walls and anything below grade or touching soil. Repointing soft old brick takes Type O or a lime mortar; N or S is harder than the brick and spalls the faces. Mix what the crew lays in about 2 hours, keep the sand covered so its moisture stays consistent, and never add extra cement to speed setting. Below 40 F heat the sand or water and cover the wall (TMS 602 cold-weather rules). Above 100 F, or 90 F with wind over 8 mph, wet the board and use each batch within 2 hours.
What this calculator leaves out
Grout for block cores, which is a different mix (ASTM C476, 8 to 11 in slump) sized in the cinder block calculator. Sand delivery and its minimum load, a mixer rental, water, and mortar for a second wythe or for parging. Colored mortar pigment, ordered from one lot for the whole job, since it varies between runs. The count is for laying; pointing and tuck-pointing use far less per unit.
Mistakes that cost money
- Mortar retempered more than once or used past 2-1/2 hours has lost its bond (TMS 602); dump it, do not rework it.
- Type S on above-grade brick veneer is harder than the brick; it cracks the units instead of the joints. Type N above grade.
- Bag yields assume 3/8 in joints and mild weather; hot wind dries the board and a bag lays 10 to 20 percent fewer units.
- Concrete sand in place of masonry sand makes a harsh mix that will not tool or hold water; order ASTM C144 masonry sand.
- Laying below 40 F without heated sand or water: the mortar freezes before it hydrates and the joints crumble (TMS 602 cold weather).
- Extra Portland stirred into a bag mix to speed the set makes brittle, shrinking joints in a color that no longer matches.
Key facts
- An 80 lb bag of mortar mix yields about 0.7 cubic feet and lays about 37 modular bricks or 13 standard blocks.
- A 60 lb bag yields about 0.53 cubic feet and lays about 27 bricks or 10 blocks.
- 1,000 modular bricks with 3/8 in joints need about 27 bags of 80 lb mortar mix, or about 10 bags of masonry cement and 3/4 cubic yard of sand mixed 1 to 2.25.
- Type N mortar (750 psi) is the standard for above-grade brick veneer; Type S (1,800 psi) is used below grade and for block foundations and retaining walls.
- Mortar should be used within 2 to 2.5 hours of mixing and can be retempered with water only once during that time.
Frequently asked questions
Can I reuse mortar that has started to stiffen?
Once, within 2-1/2 hours of mixing. Add a little water and remix to bring back workability; TMS 602 allows that. After 2-1/2 hours, or a second stiffening, the cement has started to set and more water only breaks the bond, so dump it. On a hot, windy day the window is about 2 hours.
How many bags of mortar per 100 blocks?
About 8 bags of 80 lb mortar mix, or 9 with 10% waste, at 13 blocks per bag.
How much mortar do I need for 1,000 bricks?
About 27 bags of 80 lb mortar mix, or 30 bags with waste. As a site mix at 1 part masonry cement to 2.25 parts sand, roughly 10 bags of cement and 3/4 cubic yard of sand.
What is the difference between Type N and Type S mortar?
Type N is a medium-strength mortar (750 psi) for above-grade brick and general use. Type S is stronger (1,800 psi) for block foundations, retaining walls and anything in contact with the ground.
Sources and references
- QUIKRETE Mortar Mix No. 1102 product data sheet (Quikrete)
- QUIKRETE Masonry Cement product page (Quikrete)
- Sakrete Mortar Mix Type N product page (Sakrete)
- Sakrete Mortar Mix Type S product page (Sakrete)
Next steps for this project
The usual order for a concrete & masonry project. See all concrete & masonry calculators.
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Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.