Mortar Calculator for Bricklaying
Get the brick count from the brick calculator in this section first, then use it here for the mortar that beds them. How much each brick takes depends on wall thickness and joint width, so it is an input: about 0.3 L per brick for a half-brick skin with 10 mm joints, 0.5–0.6 L for a solid wall. 500 bricks × 0.3 L is 150 L, and 15% for droppings brings it to 172.5 L — at 13 L a bag that is 13.3, so 14 bags.
Your numbers
Bags needed
14bags
Mortar volume
172.5L
Volume
0.1725m³
Formula
Mortar volume = Bricks needed × Mortar per brick × (1 + Waste allowance ÷ 100), Bags needed = ⌈Mortar volume ÷ Yield per bag (L)⌉
Mortar falls off the trowel and goes off on the spot board, so a 5% allowance is not enough; 15% is closer to site reality. Mixed mortar has to be used within about two hours, so do not gauge more than you can lay.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Bricks neededBricks needed with mortar joints and waste counted. | 500 | 0 and up |
| Mortar per brick (L)Mortar to bed one brick: about 0.3 L for a half-brick skin with 10 mm joints, 0.5–0.6 L for a solid wall. | 0.3 | 0 and up |
| Yield per bag (L)The volume one bag makes once mixed — copy the yield printed on the bag. | 13 | 0 and up |
| Waste allowance (%)The extra bought to cover breakage and offcuts. | 15 | 0 ~ 50 |
Step by step
Quick reference table
Results when only Bricks needed changes and everything else stays put.
| Bricks needed | Bags needed (bags) | Mortar volume (L) | Volume (m³) |
|---|---|---|---|
| 250 | 7 | 86.3 | 0.0862 |
| 375 | 10 | 129.4 | 0.1294 |
| 500 | 14 | 172.5 | 0.1725 |
| 750 | 20 | 258.8 | 0.2588 |
| 1,000 | 27 | 345 | 0.345 |
What each result means
| Result | At default values |
|---|---|
| Bags needed (bags)How many bags to buy; they are not sold in fractions, so this rounds up. | 14 |
| Mortar volume (L)The volume of mortar to gauge, waste included. | 172.5 |
| Volume (m³)The space a solid holds — length cubed. | 0.1725 |
Common mistakes
Mortar falls off the trowel and goes off on the spot board, so a 5% allowance is not enough; 15% is closer to site reality. Mixed mortar has to be used within about two hours, so do not gauge more than you can lay.
Glossary
- Bricks needed
- Bricks needed with mortar joints and waste counted.
- Mortar per brick
- Mortar to bed one brick: about 0.3 L for a half-brick skin with 10 mm joints, 0.5–0.6 L for a solid wall.
- Yield per bag (L)
- The volume one bag makes once mixed — copy the yield printed on the bag.
- Waste allowance
- The extra bought to cover breakage and offcuts.
- Bags needed
- How many bags to buy; they are not sold in fractions, so this rounds up.
- Mortar volume
- The volume of mortar to gauge, waste included.
- Volume
- The space a solid holds — length cubed.
Frequently asked questions
Q. How is Mortar Calculator for Bricklaying calculated?
Mortar volume = Bricks needed × Mortar per brick × (1 + Waste allowance ÷ 100), Bags needed = ⌈Mortar volume ÷ Yield per bag (L)⌉ — Get the brick count from the brick calculator in this section first, then use it here for the mortar that beds them. How much each brick takes depends on wall thickness and joint width, so it is an input: about 0.3 L per brick for a half-brick skin with 10 mm joints, 0.5–0.6 L for a solid wall. 500 bricks × 0.3 L is 150 L, and 15% for droppings brings it to 172.5 L — at 13 L a bag that is 13.3, so 14 bags.
Q. Can you walk through an example?
With Bricks needed 500, Mortar per brick 0.3L, Yield per bag (L) 13, Waste allowance 15%, the answer is Bags needed 14bags.
Q. What do I need to enter?
Enter Bricks needed, Mortar per brick, Yield per bag (L), Waste allowance. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Bricks needed moves the answer to Bricks needed 250 → Bags needed (bags) 7 and Bricks needed 1,000 → Bags needed (bags) 27. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Mortar falls off the trowel and goes off on the spot board, so a 5% allowance is not enough; 15% is closer to site reality. Mixed mortar has to be used within about two hours, so do not gauge more than you can lay.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.