How the calculation works
Premixed bags = round up [(units to lay ÷ stated units per bag) × allowance factor].
A worked example
100 blocks at up to 13 blocks per bag require 8 bags before allowance; with 10% extra, round up to 9 bags.
How many mortar bags do I need for 100 blocks?
At the QUIKRETE #1136 example coverage of up to 13 standard blocks per 80 lb bag, 100 blocks need 8 bags before allowance, or 9 with a selected 10% allowance. Actual joint and bedding conditions change use.
What to check before using the result
- Coverage is an estimating assumption, not an exact joint-volume model.
- This tool does not confuse masonry cement plus sand with a premixed mortar product.
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References & product information
Method prepared 2026-10-21. See our calculation and editorial methods. Spotted a problem? Tell us about it.