Mortar Bag Coverage: Blocks and Bricks Per Bag
Quick answer
One 80 lb bag of preblended mortar lays 16 concrete blocks or 50 bricks on the CMHA estimating basis, and 13 blocks or 37 bricks on the QUIKRETE data sheet basis. One hundred standard blocks therefore takes 7 bags by the CMHA figure or 8 bags by the manufacturer figure. All figures assume face shell bedding and a three eighths inch joint.
Blocks and bricks per bag or batch
Face shell bedding. The CMHA figures are a trade average published across nominal widths.
| Mortar | Per batch | CMU laid | Bricks laid |
|---|---|---|---|
| Preblended mortar | 1 x 80 lb bag | 16 | 50 |
| Preblended mortar, bulk | 1 x 3,000 lb bag (approx 25 ft³ yield) | 420 | 1,550 |
| Masonry cement plus sand | 8 x 70 lb bags cement + 1 ton sand | 240 | 1,000 |
| Type M | 1 : 0.25 : 3.75 (cement : lime : sand, ft³) | 38 | 187 |
| Type S | 1 : 0.5 : 4.5 (cement : lime : sand, ft³) | 46 | 225 |
| Type N | 1 : 1 : 6 (cement : lime : sand, ft³) | 62 | 300 |
| Type O | 1 : 2 : 9 (cement : lime : sand, ft³) | 93 | 450 |
Manufacturer data sheets publish their own yields, deliberately on the conservative side so a buyer does not run short.
| Product | Bag size | CMU laid | Bricks laid | Source |
|---|---|---|---|---|
| QUIKRETE Mason Mix, 80 lb bag | 1 x 80 lb bag | 13 | 37 | QUIKRETE Mason Mix, Product No. 1136, product data sheet |
| QUIKRETE Mortar Mix, 80 lb bag | 1 x 80 lb bag | 13 | 37 | QUIKRETE Mortar Mix, Product No. 1102, product data sheet |
| QUIKRETE, 3,000 lb bulk | 1 x 3,000 lb bag | 530 | 1,400 | QUIKRETE Mortar Mix / Mason Mix product data sheet (unverified, data sheet URL pending) |
| Sakrete, 80 lb bag | 1 x 80 lb bag | 12 | 35 | Sakrete product data sheet (unverified, data sheet URL pending) |
Unverified rows are shown pending confirmation of the manufacturer data sheet URL.
The two bases are not in conflict. They measure different things and each is correct on its own terms. Order to the data sheet on the bag you are buying, and use the CMHA figure as a cross check. The reasoning is set out on the block mortar calculator.
Bags needed by block count
Rounded up to whole bags. No waste allowance added, so add your own on top.
| Blocks | 80 lb bags (CMHA basis) | 80 lb bags (QUIKRETE basis) |
|---|---|---|
| 100 | 7 | 8 |
| 200 | 13 | 16 |
| 300 | 19 | 24 |
| 500 | 32 | 39 |
| 1,000 | 63 | 77 |
Bags needed by brick count
| Bricks | 80 lb bags (CMHA basis) | 80 lb bags (QUIKRETE basis) |
|---|---|---|
| 500 | 10 | 14 |
| 1,000 | 20 | 28 |
| 1,500 | 30 | 41 |
Bags per 100 square feet of wall
A conventional unit with an 8 by 16 inch face covers eight ninths of a square foot, so 100 square feet of wall takes 112.5 units before waste and 119 with a 5 percent allowance.
| Units per 100 ft² | 80 lb bags (CMHA basis) | 80 lb bags (QUIKRETE basis) |
|---|---|---|
| 112.5 (No waste) | 8 | 9 |
| 119 (5 percent waste) | 8 | 10 |
Mixing water per bag
Water quantity comes from the product data sheet, not from an estimating table, and it varies by product.
| Bag size | Water (quarts) | Source |
|---|---|---|
| 80 lb bag | 5 | QUIKRETE Mason Mix, Product No. 1136, product data sheet |
| 60 lb bag | 3.75 | QUIKRETE Mason Mix, Product No. 1136, product data sheet |
Add the water to the mixer first, then the bag. A workable consistency is reached when a half inch thickness of mortar stays on a trowel held close to vertical. Add further water in small amounts only.
What changes the coverage
Four things move these numbers, and only one of them is the mortar type.
Bedding method. Every figure here assumes face shell bedding, with the webs left bare. Full bedding covers the webs as well and uses noticeably more material. If the specification calls for full bedding, which it may for a starting course on a footing or for solid units, these quantities will run short.
Joint thickness. The standard joint is three eighths of an inch, and that dimension is why a nominal 8 by 8 by 16 inch block actually measures 7 and 5 over 8 by 7 and 5 over 8 by 15 and 5 over 8 inches. A half inch joint consumes materially more mortar. See the cinder block dimensions reference.
Unit width. The CMHA figures are published on one basis for all widths. Manufacturer tables vary with width, because ASTM C90 sets a minimum face shell thickness of 0.75 inch at 4 inch nominal, 1.00 inch at 6 inch, and 1.25 inch at 8 inch and above. A wider unit carries a deeper bed.
Waste. None of the tables on this page include a waste allowance. CMHA uses 119 units per 100 square feet as its block figure with 5 percent included, against 112.5 without. Apply waste to the mortar and to the units separately.
Mortar type is not on that list. Type N and Type S versions of the same preblended product publish identical yields, because the type changes the proportions inside the bag, not how much mortar a joint holds.
What these figures do not cover
Special units are estimated separately and subtracted from the stretcher count: pilaster, corner, bond beam and lintel units all bed differently.
Collar joints between wythes, parging, and repointing existing work all consume mortar on a different basis and are not covered here.
Grout is a different material and a different calculation. Grout fills the cells, mortar bonds the units. For cell fill, use the block fill calculator. For unit counts, use the cinder block calculator. For which mortar type a job calls for, see the mortar guide for block walls.
Sources
CMHA TEK 04-02A, Estimating Concrete Masonry Materials. Units laid per bag and per site mixed batch, and unit coverage per 100 square feet.
QUIKRETE Mason Mix, Product No. 1136, product data sheet. Yield and mixing water per bag.
QUIKRETE Mortar Mix, Product No. 1102, product data sheet. Type N formulation with identical published yield.
Structural safety notice
This guide is general information for planning only and is not a substitute for a licensed structural or civil engineer. Do not rely on it for load-bearing, safety-critical, or code-compliance decisions.