Mortar & Grout Calculator — ft, bags, cost
How to use this calculator
Choose a mode: mortar for brick walls, mortar for block walls, grout for CMU fill, or custom volume entry. Enter wall dimensions and the calculator estimates bags of mortar or grout needed, total volume, and weight.
Mortar Types — Type M (2 500 psi, below-grade), Type S (1 800 psi, structural), Type N (750 psi, general), Type O (350 psi, interior).
Bag Sizes — 60 lb and 80 lb pre-mixed mortar bags.
Waste — 10–15% typical for mortar, 5–10% for grout.
Saved Calculations
| Time | Mode | Area ft² | Vol ft³ | Bags | Weight lbs | Cost |
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How to Use This Mortar & Grout Calculator
Pick the mode that matches your work. Brick Mortar uses the selected unit size and joint thickness to size bed and head joints per course. Block Mortar assumes face-shell bedding on 8×8×16″ coursing (1.125 units/ft²). Block Grout fills cores by block width and fill spacing. Custom lets you enter a known volume from a takeoff. Enter wall length and height, set a waste allowance, and the calculator returns net volume, volume with waste, bag count, weight and cost. For a full unit count and wall takeoff, start with the brick wall calculator or the block wall calculator, then size mortar and grout here.
Formulas
Brick mortar per ft² = bricks/ft² × (bed joint + head joint) volume, where bricks/ft² = 144 / [(L+joint)(H+joint)]. Grout fill (ft³) = wall area × core volume per ft² of face × fill fraction. Bags = ⌈volume×(1+waste) / bag yield⌉, rounded up to whole bags. Bag yield: 80 lb ≈ 0.5 ft³ mixed, 60 lb ≈ 0.38 ft³ mixed.
On the jobsite
Mortar follows ASTM C270 — Type S for structural and exterior, Type N general above-grade, Type M below grade or retaining, Type O for interior non-load partitions. Grout follows ASTM C476 with an 8–11″ slump for cell fill. 2025 USA pricing: 80 lb pre-mixed mortar runs $7–10/bag at the box store, 60 lb bags $5–7, and coarse grout 80 lb $9–13. The number-one mistake masons make on takeoff is undercounting head joints — bed joints alone get you about 60% of the real volume, so the calculator includes both. Carry 10–15% waste for mortar (board loss, droppings, partial bags) and 5–10% for grout, more on pilasters and arches. Standard brick with ½″ joints runs roughly 7 bags (80 lb) per 100 ft² of wall; an 8″ CMU wall with all cells grouted uses about 0.5 ft³ of grout per block. Downstream, estimate the retaining wall or stone veneer setting bed, and for poured cores or bond beams compare with the concrete bag calculator. Working in metric? Use the metric mortar & grout calculator.
FAQ
How many bags of mortar per 100 brick? About 0.045 yd³ (1.2 ft³) of mortar per 100 modular brick with ⅜″ joints — roughly 2–3 80 lb bags. Does the calculator include waste? Yes — the bag count uses the volume with your waste allowance and rounds up. Mortar vs. grout? Mortar bonds units at the joints; grout is a fluid mix poured into CMU cores to bond reinforcement — use the Block Grout mode for cores.
