Floors & Walls
Mortar Calculator
Estimate mortar bags from a masonry unit count and a matching units-per-bag yield.
Enter your measurements
Results update as you type.
About this calculator
Enter how many bricks or blocks you are laying, plus the units-per-bag figure for your mortar and joint size from the supplier. The estimate adds an allowance for broken units and waste, then rounds up to whole bags. The yield must match your unit type and joint — the calculator will not apply a universal brick-to-bag ratio.
How to measure
- Count the masonry units to lay, rather than their surface area.
- Get units-per-bag yield for the matching unit type and joint size from the supplier.
- Confirm that yield basis and enter any extra allowance separately.
How to use this calculator
- Count the bricks or blocks to lay.
- Find the units-per-bag figure matching your unit type and joint size.
- Add an allowance for breakage and waste.
- Calculate for bags to buy.
Formula
Equivalent units = unit count × (1 + allowance ÷ 100)
Bags = ⌈equivalent units ÷ units laid per bag⌉
Exact multiples receive no extra bag
Assumptions
- Yield is supplied by the manufacturer for the same unit type and joint thickness.
- Unit count must be a whole number.
- Zero units returns zero bags.
Common mistakes
- Using a coverage or yield for a different product, depth or application.
- Adding waste twice in both the measured quantity and allowance field.
- Treating a bag count as proof that the selected product is suitable for the installation.
Worked example
Try it: press “Load example” above the form.
1,000 bricks with 10% allowance is 1,100 equivalent units; at 50 per bag that is 22 bags.
Limitations
No mortar type selection, sand/cement recipe, structural suitability or universal brick-to-bag ratio.
Frequently asked questions
What does units per bag mean?
It is the stated number of the selected bricks or blocks laid per bag at a specific joint size. The example of about 13 standard blocks applies to an 80 lb QUIKRETE mortar mix bag.
Why confirm the yield?
Brick size, hollow block geometry, joint thickness and waste change consumption. Confirm the product chart and unit type before using a per-bag figure to purchase mortar.
What does the worked example show?
1,000 bricks with 10% allowance is 1,100 equivalent units; at 50 per bag that is 22 bags.
Which assumptions should I check before using the result?
No mortar type selection, sand/cement recipe, structural suitability or universal brick-to-bag ratio.
Sources
Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.
- QUIKRETE: product quantity calculators
Product-specific coverage and yield context; this tool uses only the yield you supply.
- QUIKRETE mortar mix yield
≈13 standard 8×8×16 in blocks per 80 lb bag at 3/8 in joints; yield varies by unit and joint.
Calculation documentation · Updated 2026-11-08 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.
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