About the Mortar Calculator
Mortar coverage per bag depends heavily on joint thickness and unit size, which is why this calculator treats units-per-bag as an adjustable figure rather than a fixed constant.
How It Works
The calculator divides your total brick or block count by how many units a single 80lb bag typically covers, based on your project's joint thickness and unit size, to estimate total bags needed.
Examples
A small brick project
500 bricks at 30 units per bag needs about 16.7 bags, rounding up to 17 full bags.
A block wall with thicker joints
500 blocks at a lower 25 units per bag due to thicker joints needs 20 bags instead, a meaningful difference from the brick example.
Advantages
- Adjustable units-per-bag figure to match brick, block, or specialty mortar
- Simple two-field input for a fast bag count estimate
- Rounds up to the next full bag automatically
Common Mistakes
- Using a brick yield figure for a block project or vice versa
- Mixing more mortar than can be used within about 2 hours
- Not accounting for joint thickness when estimating yield per bag
Edge Cases to Watch For
- Standard bricks with a 3/8 inch joint yield roughly 30 units per 80lb bag, while concrete blocks typically yield 25-33 depending on block size; always adjust the default to match your specific materials.
- Mixed mortar that isn't used within about 2 hours (sooner in hot weather) should be discarded rather than reused, since it starts losing workability and bond strength as it stiffens.
- Colored or specialty mortar mixes may have different yield figures than standard type N or type S mortar, check the product's technical data sheet.
Common Use Cases
- Estimating mortar bags for a brick or block wall project
- Budgeting a masonry repair or repointing job
- Comparing material needs between different joint thicknesses