Mortar Calculator
Joint volume, product yield, and waste
Enter masonry quantity, dimensions, and mortar supply data
Result
Calculation summary
Enter values to see the result
Mortar joint and supply preview
Brick mortar estimate
How to use this calculator
- 1Enter the number of bricks or blocks, then choose a dimension-labeled preset or enter all three installed unit dimensions.
- 2Confirm the mortar joint and joint fill factor. Solid brickwork commonly uses a full-bed planning model, while hollow units need a project-specific face-shell factor.
- 3Choose site-mixed volume or preblended bags. For bags, use either the stated mixed yield or the manufacturer’s units-per-bag coverage.
Formula
Mortar = units × (((length + joint) × (height + joint) − length × height) × depth) × fill factor × (1 + waste)
The geometry method compares one unit-and-joint module with the unit face, extends that joint area through the unit depth, and scales the result by fill and waste.
Calculation steps
- Validate unit count, dimensions, joint, fill factor, waste, and product data.
- Convert unit dimensions and joint width to meters.
- Calculate the theoretical full-depth joint volume around one unit.
- Apply the joint fill factor, multiply by the unit count, and add the waste allowance.
- For preblended mortar, divide by bag yield or manufacturer coverage and round up to whole bags.
Worked example
For 1,000 bricks measuring 240 × 115 × 53 mm with 10 mm joints, a 100% full-bed factor gives about 348.45 L before waste. Adding 10% gives 383.295 L; at 15 L per bag, the estimate rounds up to 26 bags.
Assumptions
- The geometry model uses rectangular units and uniform horizontal and vertical joints. Frogs, perforations, cores, tooling, bond pattern, corners, and workmanship can change actual usage.
- The joint fill factor is an explicit planning adjustment, not a standardized property. Verify face-shell bedding and unit geometry for hollow blocks.
- Bag yield, bag coverage, and bag weight are product inputs. Defaults are editable examples and are not manufacturer specifications.
- Waste represents mixing, handling, tooling, spillage, and site variation; the appropriate allowance depends on the project.
- Site-mixed mode estimates wet mortar volume only. It does not prescribe mortar type, cement-to-sand proportions, strength, structural design, or code compliance.
Sources
- TEK 04-02A — Estimating Concrete Masonry Materials — Concrete Masonry & Hardscapes Association
- Technical Note 10 — Dimensioning and Estimating Brick Masonry — Brick Industry Association
- Technical Note 8 — Mortars for Brickwork — Brick Industry Association
- Handbook 133 (2026), Appendix E — General Tables of Units of Measurement — National Institute of Standards and Technology
Frequently asked questions
Should I use bag yield or units per bag?
Use mixed yield when the product states a reliable wet volume per bag. Use units per bag when the manufacturer gives coverage for your exact unit size, joint, and bedding method.
What is the joint fill factor?
It scales the full-depth rectangular joint model. Use 100% for a full-bed planning estimate; hollow block face-shell bedding normally needs a lower project-specific factor based on the unit and workmanship.
Why can actual mortar use differ?
Unit cores or frogs, joint tooling, bond, corners, inconsistent dimensions, weather, mixing losses, work stoppages, and mason technique can all change consumption.
Does site-mixed mode calculate cement and sand?
No. It returns wet mortar volume so the project specification or supplier can determine approved materials and proportions. Mortar type and mix selection should not be inferred from volume alone.
Can I import a brick or block estimate?
Yes. Calculate the masonry unit quantity first, then open this calculator from the result card to carry the unit count, material preset, dimensions, joint, and matching units into the mortar estimate.