Masonry / Bag quantity estimator
Mortar Calculator
Estimate preblended mortar bags from your brick or block count. Set coverage, add extra, and plan whole bags to buy.
Your material estimate
Live resultMortar needed · Bags to buy
15bags
10% extra included. Rounded up once after extra is added.
- Base estimate
- 13.51 bags
- + 10% extra
- 1.35 bag-equivalent
- Adjusted estimate
- 14.86 bags
- Final order
- 15 bags
- Masonry units
- 500 standard bricks
- Bag size
- 80 lb
- Coverage used
- 37 bricks per bagPreset reference
- Joint reference
- ≈ 3/8 in (9.5 mm)
Coverage is a planning reference. Verify the mortar product and published coverage before purchasing.
Understand your estimate
How the Mortar Calculator Works
Enter the number of standard bricks or concrete blocks you plan to lay. The calculator divides the unit count by the estimated coverage of one bag of mortar, adds the selected extra-material allowance, and rounds the result up to a whole bag.
The formula
- Adjusted bags = base bags × (1 + extra % / 100)
- Order bags = ceil(adjusted bags)
- Estimated cost = order bags × price per bag
Extra is applied to the unrounded base estimate. Only the final order is rounded up to a whole bag. For 500 bricks at 37 bricks per bag with 10% extra: 13.5135 base bags → 14.8649 adjusted bags → 15 bags to buy.
Bag coverage explanation
Bag coverage varies by mortar product, masonry unit, joint dimensions, and jobsite conditions. The calculator provides editable reference coverage for common preblended mortar bag sizes. For the best estimate, use the coverage published for the mortar product you plan to buy.
For standard bricks, 40 / 60 / 80 lb reference bags cover 19 / 28 / 37 bricks. For standard concrete blocks, they cover 6 / 9 / 12 blocks. Bag weight selects a reference; actual calculation uses your entered coverage.
Mortar joint reference
Reference coverage is based on standard masonry units with approximately 3/8 in (9.5 mm) mortar joints. If your project uses different units or joint dimensions, use product-specific coverage when available.
Joint thickness is a reference assumption, not an input. No generic joint correction is applied.
Assumptions & limitations
Standard Brick uses an 8 × 2 × 4 in reference size; Standard Concrete Block uses 8 × 8 × 16 in. These are coverage conditions, not universal dimensions. Bedding method, workmanship, spillage, and product yield can change usage.
Default extra is 10%, editable from 0% to 100%, to allow for waste, spillage, masonry-unit variation, and jobsite conditions. Cost is optional, in USD, based on whole bags and excludes tax, delivery, and labor.
This estimate is for preblended bagged mortar. It does not estimate site-batched mixes, grout, repointing, tuckpointing, or stone veneer mortar, or recommend mortar strength or structural suitability.
Frequently asked questions
How many bags of mortar do I need?
Divide your masonry unit count by coverage per bag, add your selected extra percentage, then round up once to a whole bag. Use the product's published coverage for the best estimate.
How many bricks will one bag of mortar lay?
It depends on the product, brick dimensions, joints, and laying conditions. The 80 lb reference starts at 37 standard bricks per bag; reference coverage is editable to match your product.
How many concrete blocks will one bag of mortar lay?
Use the product's coverage for your concrete blocks and bedding method. The 80 lb reference starts at 12 standard concrete blocks per bag and can be edited.
Does mortar joint thickness affect how much mortar I need?
Yes. Joint dimensions and masonry geometry affect usage, but this calculator does not apply a generic joint correction. Use product-specific coverage for your units and joints.
How much extra mortar should I allow?
The default is 10%. You can select 0%, 5%, 10%, or a custom allowance from 0% to 100%. Confirm an appropriate allowance for waste, spillage, and jobsite conditions with your supplier or contractor.
What mortar type should I use?
Mortar type depends on the masonry system, exposure, structural requirements, and applicable project specifications. This calculator estimates quantity only.