Mortar quantity depends on more than just the size of the wall — the unit type (brick vs. CMU block), the bedding method, and the joint thickness all change how much mortar a wall actually needs. This calculator turns those variables into a bag count you can take to the supply store.
How the Mortar Mix Calculator works
This model uses QUIKRETE Mortar Mix 1102 premixed 80-lb bags: up to 37 standard bricks or 13 standard blocks per bag at the reference 3/8-inch joint. Different products and site conditions change yield. Joint scaling is an estimate; masonry cement with separately added sand uses a different basis.
Inputs and what they mean
Unit type sets the base coverage figure (brick vs. CMU) — pick Custom if you're using a specialty unit and have its manufacturer-published units-per-bag coverage.
Unit count or wall area drives the total quantity. If you have an exact material takeoff, use the unit count directly on the Bags Needed tab — it's always more accurate than an area-based estimate, since area estimates assume a standard running-bond layout with no unusual cutting.
Joint thickness defaults to the US-standard 3/8 in. Restoration work on older/thinner historic brick sometimes uses a 1/4 in joint; some specialty or oversized units use up to 1/2 in.
Waste allowance covers mortar that's mixed but not used, spilled during tooling, or lost to cut units at corners and openings. 5% suits a simple rectangular wall; 15% suits a wall with many returns, openings, or curves.
Limits and edge cases
This calculator estimates material quantity, not structural adequacy — it doesn't check load-bearing capacity, reinforcement requirements, or local building code compliance. For structural masonry (load-bearing walls, retaining walls over a few feet tall, or anything requiring an engineer's stamp), consult a structural engineer or your local building department.
The area-based estimate on the By Wall Area tab assumes a standard running-bond layout with no openings subtracted — for walls with many doors, windows, or an unusual bond pattern, an exact unit count (or a supplier materials takeoff) will be more accurate than the area estimate.
Mortar coverage also varies somewhat by manufacturer and mix design; the figures here reflect commonly published mid-range coverage data, not a single manufacturer's exact spec sheet. Always check the coverage stated on your specific mortar bag before finalizing a large order.