How this calculator works
Divide the number of masonry units by the published number laid per bag, add a chosen allowance and round up. The manufacturer reference is for an 80 lb bag of QUIKRETE Mason Mix with standard bricks or nominal 8 x 8 x 16 in blocks. Its data sheet lists a rounded metric bag mass of 36.2 kg. Custom mode lets you enter both coverage and bag mass for Canadian products or another bedding arrangement. The mass output is all purchased dry mortar, including unused bag contents.
Formula
Bag equivalent = masonry units x (1 + allowance) / units per bag; whole bags = ceil(bag equivalent); purchased dry mass = whole bags x dry bag mass.
Worked example
Seventy-four standard bricks at 37 bricks per bag need two bags with no extra allowance, or 72.4 kg using the listed metric package mass. Twenty-seven standard blocks at 13 per bag need three bags.
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Frequently asked questions
Does one coverage value suit every block?
No. Unit dimensions, bedding pattern and joint thickness change usage. Replace the reference with package or field coverage for your wall.
Is this cement only?
No. These are pre-blended mortar bags containing the constituents listed by the manufacturer. A bag of cement alone has a different yield.
Why round after the allowance?
The allowance covers handling loss and small variations before purchasing whole bags. Rounding first can overstate small jobs.