Mortar Calculator
Estimate wet mortar volume around a known number of bricks or blocks.
Last reviewed September 19, 2026
Result
Buy 5.8057 ft³Estimate
No extra is added by default because technique and site losses vary. Use Custom if you want to allow for droppings and uneven joints.
- Geometric joint volume
- 5.8057 ft³
- Mortar per unit
- 13.93 in³
https://calcgallery.com/masonry/mortar-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Enter the number of bricks or blocks from the matching wall calculator or drawing.
- Enter actual unit length, height and depth, not nominal module size.
- Enter the bed and head joint width.
- Read the wet mortar volume, then compare it with the yield on the product you will use.
How it is calculated
Each brick or block occupies its actual envelope plus one repeating bed joint and one repeating head joint. The difference is mortar:
Module = (length + joint) × (height + joint) × depth
Mortar = count × (module − unit envelope)The boundary of a real wall has half-joints and exposed edges, but across hundreds of repeating units the module method is a useful material estimate.
Practical limits
Use actual dimensions. A nominal 8 × 8 × 16 in block is normally smaller so the unit plus joint lands on the nominal module. Entering nominal size and then adding a joint counts that space twice.
Check product yield. Premixed mortar labels often state coverage for a particular brick and joint. Compare that scenario with yours before converting volume to bags.
Grout is separate. Mortar holds units together; grout fills selected cores. Reinforced masonry drawings specify which cores are filled.
Keep batches consistent. Joint appearance changes with water content and mix time. Measuring the same way each batch matters as much as the total quantity.
With your numbers
- Module = (7.625 in + joint) × (2.25 in + joint) × 3.625 in
- 720 units leave 5.806 ft³ for regular joints
- With 0% extra = 5.8057 ft³
Quick reference
No extra is added by default because technique and site losses vary. Use Custom if you want to allow for droppings and uneven joints.
| Job | Wet mortar needed |
|---|---|
| 720 US modular bricks | 5.8057 ft³ |
| 500 US modular bricks | 4.0317 ft³ |
| 250 nominal 8 in blocks | 9.7733 ft³ |
| 100 thin veneer bricks | 0.1668 ft³ |
| 600 UK standard bricks | 178.35 L |
| 250 metric blocks | 280.25 L |
Common questions
- How much mortar do 720 US modular bricks need?
- With 7.625 × 2.25 × 3.625 in bricks and 3/8 in joints, the regular geometric joint volume is about 5.81 ft³ before site losses.
- Why does this not give a bag count?
- Bag yields vary with product, mix ratio, water and whether the stated coverage assumes a particular unit. Divide this wet volume by the yield printed for your unit and joint.
- Does it work for concrete blocks?
- Yes for regular full-depth bed and head joints. Enter the actual block envelope dimensions and depth. It does not estimate grout placed inside block cores.
- Is the result exact?
- The geometry is exact for a repeating rectangular module. Real walls use cut units, furrowed beds, varying joints and mortar droppings, so the amount purchased remains an estimate.