Bags of mortar for a block or brick wall
Mortar Calculator
A 20 ft long, 4 ft high wall takes 90 blocks to lay, or 95 with 5% waste, 7 to 8 bags of 80 lb mortar mix, by maker label. Enter your wall or count below.
Sources checked
Your estimate
7 to 8 bags
80 lb mortar mix for 90 blocks to lay, rounded up for each label.
- Mortar: QUIKRETE Mortar Mix 1102, Nov 2020 sheet90 ÷ 13 blocks a bag (80 lb, Type N), rounded up7 bags
- Mortar: QUIKRETE Mortar Mix 1102, older undated sheet90 ÷ 12 blocks a bag (80 lb, Type N), rounded up8 bags
- Mortar: SAKRETE Mortar Mix Type S, US90 ÷ 12 blocks a bag (80 lb, Type S), rounded up8 bags
- Blocks to lay80 sq ft × 1.125 blocks a sq ft, rounded up90
- Blocks to buy90 plus 5% waste95
Mortar is counted on the units laid. Sand and grout are not in our data: the mortar mix needs only water, and cell fill for a block wall is not counted.
How to calculate mortar for a wall
- Measure the wall, or count its units. The example is 20 ft × 4 ft, 80 sq ft with no openings.
- Count the blocks laid: 80 sq ft × 1.125 blocks a sq ft = 90 blocks. The blocks to buy add waste: 95 at 5%.
- Divide the blocks laid by the blocks one bag lays, for each label, and round up to whole bags: 90 ÷ 13 = 7 bags for QUIKRETE’s November 2020 sheet, and 90 ÷ 12 = 8 for SAKRETE.
- For bricks, count the bricks and divide by the bricks one bag lays: 37 for QUIKRETE, 35 for SAKRETE. Bricks cannot be counted from a wall size in our data.
This counts the mortar for a straight wall, not a design. The bag labels print how far a bag goes at a joint thickness they state; a thicker bed or a rougher block needs more. Buy the higher count if you are unsure, and keep the spare bag unopened.
Bags of mortar for block counts
| Blocks laid | QUIKRETE, Nov 2020 (13 a bag) | QUIKRETE, older (12 a bag) | SAKRETE, US (12 a bag) |
|---|---|---|---|
| 100 | 8 | 9 | 9 |
| 250 | 20 | 21 | 21 |
| 500 | 39 | 42 | 42 |
| 1,000 | 77 | 84 | 84 |
The example wall, 20 ft × 4 ft, is 90 blocks laid, so 7 to 8 bags at 80 lb.
How much mortar per bag
Bag labels print how many blocks and bricks one bag lays. They do not agree, so the calculator shows each. The three block labels are for 8×8×16 units; brick counts are for a brick the labels do not size.
Blocks one 80 lb bag of mortar mix lays (8×8×16)
- QUIKRETE Mortar Mix 1102, Nov 2020 sheet, Type N: 13 blocks laidQUIKRETE Mortar Mix No. 1102 data sheet (Nov 2020)
- QUIKRETE Mortar Mix 1102, older undated sheet, Type N: 12 blocks laidQUIKRETE Mortar Mix No. 1102, older data sheet (undated)
- SAKRETE Mortar Mix Type S, US, Type S: 12 blocks laidSAKRETE Mortar Mix Type S spec sheet, US (Rev. 05/18)
The form shows a bag count for each label, and the lead gives the range: 7 to 8 bags for 90 blocks. If you buy once, buy the higher count. Mix type, joint thickness and waste change what a bag lays.
Standard bricks one 80 lb bag of mortar mix lays
- QUIKRETE Mortar Mix 1102, Nov 2020 sheet, Type N: 37 bricks laidQUIKRETE Mortar Mix No. 1102 data sheet (Nov 2020)
- SAKRETE Mortar Mix Type S, US, Type S: 35 bricks laidSAKRETE Mortar Mix Type S spec sheet, US (Rev. 05/18)
Both labels say standard brick without a size, so the count is per brick, not per square foot. Enter your brick count in the form.
Our data has 60 and 40 lb bag coverage for blocks only, from the two older labels. Brick coverage is printed for 80 lb bags only.
Sand per bag of mortar
Mortar mix is sold premixed: add water and mix. The mix labels above give no sand figure, because none is added. For masonry cement, one 70 lb bag mixed with 240 lb of mason’s sand yields about 2.75 cu ft of mortar, from QUIKRETE’s Type S No. 1125-71 sheet. That is the only sand figure in our data. QUIKRETE Masonry Cement Type S No. 1125-71 data sheet
Mixing your own Portland cement and sand to a mortar ratio is not covered by our data, so this page gives no sand per bag for it. Your mix design or the masonry supplier sets that.
Grout and core fill for block cells
Filling the block cells with grout or concrete is not counted. Our data has no cell-fill volume, which is a known gap, so this page gives no grout quantity. Ask the block maker or the wall’s designer for the cells that are filled, and the grout that goes in them.
Numbers this page uses
- Blocks laid per 80 lb bag, QUIKRETE Mortar Mix 1102, Nov 2020 sheet
- 13QUIKRETE Mortar Mix No. 1102 data sheet (Nov 2020)
- Blocks laid per 80 lb bag, QUIKRETE Mortar Mix 1102, older undated sheet
- 12QUIKRETE Mortar Mix No. 1102, older data sheet (undated)
- Blocks laid per 80 lb bag, SAKRETE Mortar Mix Type S, US
- 12SAKRETE Mortar Mix Type S spec sheet, US (Rev. 05/18)
- Bricks per 80 lb bag, QUIKRETE Nov 2020 (Type N)
- 37QUIKRETE Mortar Mix No. 1102 data sheet (Nov 2020)
- Bricks per 80 lb bag, SAKRETE US (Type S)
- 35SAKRETE Mortar Mix Type S spec sheet, US (Rev. 05/18)
- Waste allowance, example
- 5%Our default; change it above
Mortar calculator questions
How many bags of mortar do I need for a block wall?
A 20 ft × 4 ft wall takes 90 blocks to lay. At 80 lb a bag, QUIKRETE’s November 2020 sheet lays 13 blocks a bag and its older sheet and SAKRETE lay 12, so 7 to 8 bags. Round up, and keep one spare for cut joints.
How many bags of mortar for a brick wall?
Our data has a count per bag, not a brick size: 37 standard bricks for QUIKRETE’s November 2020 sheet and 35 for SAKRETE’s US sheet, both at 80 lb. The size of a standard brick is not printed, so a wall’s area cannot be turned into bricks here. Count the bricks and enter the number above. For a block wall, use the concrete block calculator.
How much sand per bag of mortar?
Mortar mix comes premixed: add water only, and the sheets give no sand figure for it. For masonry cement, QUIKRETE’s Type S No. 1125-71 says one 70 lb bag mixed with 240 lb of mason’s sand yields about 2.75 cu ft of mortar. That is the only sand figure in our data; mixing your own Portland cement and sand is not covered.
How many bags of mortar per 100 blocks?
7.7 bags at 13 blocks a bag and 8.3 at 12. Round up to whole bags: 8 and 9. Mortar is counted on the blocks laid, not on the waste allowance.
Is mapei mortar the same as thinset for tile?
No. Thinset and tile mortar are adhesives with their own coverage charts. This page counts masonry mortar mix for a block or brick wall.
How much grout or core fill do block cells take?
Not counted here. Our data has no grout or cell-fill volume, so this page does not give it. Ask the block maker or the wall’s designer.
Can I use this for a block foundation?
Yes for the mortar and blocks: enter the foundation wall’s length and height and subtract the openings. For the footing concrete use the concrete calculator, and for the blocks themselves see the concrete block calculator.
Do segmental retaining wall blocks use mortar?
No. Segmental units are set dry, with setback and drainage stone, so there is no bag count. Size one with the retaining wall block calculator.
A planning aid, not an engineering calculation: your local code and building inspector have the final word. Terms