Mortar Calculator: Estimate Bags of Mortar Mix for Block & Brick
This mortar calculator estimates how many bags of mortar mix you need to lay a block or brick wall based on its size and unit count. Enter your wall dimensions to plan bags and avoid mid-job runs to the store.
Estimated concrete
Estimates only. Add ~5–10% for waste. Bag yields: 40 lb ≈ 0.30, 60 lb ≈ 0.45, 80 lb ≈ 0.60 cu ft. Concrete ≈ 150 lb per cu ft.
How to Use the Mortar Calculator
- 1
Enter your dimensions
Type the length, width and thickness of your slab, footing or pad and choose your units, feet, inches or meters.
- 2
Get instant volume
See the result in cubic yards, cubic feet and cubic meters, plus weight, the moment you type, no page reloads.
- 3
Buy the right amount
We convert volume into the exact number of 40, 60 and 80 lb bags, truck loads and cost so you order without waste or shortfalls.
The formula
bags = block_count ÷ 33 (or) bags = brick_count ÷ 135
- ·block_count = number of standard 8×8×16 blocks to lay
- ·brick_count = number of standard bricks to lay
- ·33 = blocks laid per 80 lb bag of mortar
- ·135 = bricks laid per 80 lb bag of mortar
- ·result is rounded up to whole bags
Coverage assumes standard 3/8-inch joints; thicker joints or rough units use more mortar. Round up and add a spare bag, since partial bags cannot be returned once opened.
Worked examples
Example 1: Block wall using 300 standard blocks
- Coverage = 33 blocks per 80 lb bag
- Bags = 300 ÷ 33 = 9.09
- Round up to 10 bags
Result: 10 bags of 80 lb mortar mix
Example 2: Brick veneer using 500 standard bricks
- Coverage = 135 bricks per 80 lb bag
- Bags = 500 ÷ 135 = 3.7
- Round up to 4 bags
Result: 4 bags of 80 lb mortar mix
Concrete calculators by project type
Concrete bag yield & coverage
How much mixed concrete a standard bag yields, and how far a cubic yard goes at common slab depths.
| Bag size | Yield (cu ft) | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 | 90 |
| 60 lb | 0.45 | 60 |
| 80 lb | 0.60 | 45 |
- 40 lb
- 60 lb
- 80 lb
Related guides
Mortar Calculator FAQs
How many bags of mortar do I need per 100 concrete blocks?
As a rule of thumb, you need about 3 bags of mortar mix per 100 standard 8x8x16 concrete blocks. Buy a little extra to cover waste and full joints.
How much mortar do I need per brick?
Standard brick takes roughly 7 bags of mortar per 1,000 bricks, or about one 80-pound bag for every 140 bricks. Joint size and brick type change the exact amount.
What is the difference between mortar and concrete?
Mortar is a mix of cement, sand, and lime used to bond block and brick, while concrete adds gravel aggregate for structural strength. Mortar is stickier and weaker in compression by design so it can flex slightly.
What type of mortar should I use for a block wall?
Type N mortar is the common all-purpose choice for above-grade block and brick walls. Type S is used for below-grade or load-bearing walls that need higher strength.
How many blocks does an 80-pound bag of mortar lay?
One 80-pound bag of premixed mortar lays roughly 30 to 40 standard concrete blocks. Actual coverage depends on joint thickness and how full you tool the joints.
Can I mix my own mortar instead of using bagged mix?
Yes, a common site mix is about 1 part masonry cement to 3 parts sand with water to a workable consistency. Bagged premixed mortar is more convenient and gives consistent results for small jobs.
How much sand do I need per bag of mortar?
Pre-blended bagged mortar already contains sand, so you only add water. If you mix from Portland cement and lime instead, plan on roughly 18 to 20 shovels of masonry sand per bag of cement for a typical Type S blend. Bagged mix is simpler and more consistent for most projects.
What is the difference between Type N and Type S mortar?
Type N is a medium-strength mortar for above-grade walls and general masonry, while Type S is stronger and better for below-grade work, foundations, and load-bearing block. Type S resists lateral and soil pressure more effectively. Choose based on where the wall sits and what it carries.
How much water do I add to a bag of mortar mix?
An 80 lb bag of mortar usually needs about 5 to 6 quarts (roughly 1.25 to 1.5 gallons) of water, but always follow the bag's directions. Add water gradually until the mortar holds a peak without slumping. Too much water weakens the joint and makes it hard to strike cleanly.
How long can mixed mortar sit before it goes bad?
Mixed mortar stays workable for about 1.5 to 2 hours before it begins to set. You can re-temper it once with a little water if it stiffens within that window, but never after it has started to harden. Mix only what your crew can lay in that time.
How thick should mortar joints be?
Standard mortar joints are 3/8 inch thick, which is what typical coverage figures assume. Thicker joints consume more mortar and reduce how many units a bag will lay. Consistent joint thickness also keeps courses level and the wall visually even.
Does joint thickness change mortar coverage?
Yes, coverage is tied directly to joint size. The standard estimate of about 33 blocks or 135 bricks per 80 lb bag assumes 3/8-inch joints; wider joints or rough, irregular units can cut that coverage noticeably. Order extra mortar if you expect thick joints or heavy tooling.
How many bags of mortar do I need for 1,000 bricks?
At roughly 135 bricks per 80 lb bag, 1,000 bricks need about 1000 ÷ 135 = 7.4, so 8 bags rounded up. Add a spare bag for waste and cleanup. For large veneer jobs, buying by the pallet is usually more economical.