Estimate how many bags of mortar you need from a brick or block count or wall size, using typical yields per bag or your product’s own yield.
Mortar Bag Formula
The calculator works three ways. To find the bags needed from a brick or block count, it divides the unit count (with a waste allowance added) by the yield of one bag and rounds up:
B = roundup(N * (1 + w) / Y)
To find the bags needed from wall area, it first converts the area to a unit count using the units per square foot for that brick or block, then uses the same bag formula:
N = A * u
To find the coverage of bags you already have, it multiplies the number of bags by the yield to get the units they will lay:
N = B * Y
Enter the product yield on an 80 lb reference basis. The calculator estimates yield for the selected bag weight by proportional scaling of the same mix:
Y = Y80 * (bag weight / 80)
Variables:
- B is the whole number of bags to buy, rounded up in demand modes, or the bags on hand in coverage mode
- N is the number of bricks or blocks
- w is the waste allowance written as a decimal, so 10 percent is 0.10
- Y is the yield, meaning how many units one bag of mortar lays
- Y80 is the unit’s yield for an 80 lb bag, before scaling for bag size
- A is the wall area, length times height
- u is the number of that brick or block per square foot of wall face
Pick what you want to find at the top. In count mode you enter the number of bricks or blocks and get the bags needed. In area mode you enter the wall length and height and the calculator estimates the unit count first, then the bags. Coverage mode runs it backward: enter the bags you have and it tells you how many units and how many square feet they will lay. Pick a brick or block type to use its typical yield and units per square foot, or choose Custom yield and enter your product’s values. The bag weight selector scales the 80 lb yield for the same mix. Optional settings hold the extra mortar allowance (blank uses 10%) and a price per selected bag. Coverage is gross, with no waste deducted.
Mortar Yield and Price Reference
This first table retains illustrative planning inputs from the worked examples; the calculator uses these typical values for each brick or block type. Choose Custom yield to enter your actual product and masonry. For comparison, the linked QUIKRETE Mortar Mix 1102 data sheet gives up-to coverage of 37 standard bricks or 13 standard 8 × 8 × 16 inch blocks per 80 lb bag. Check the current bag specification and joint conditions.
| Masonry unit | Units per 80 lb bag | Illustrative units per 60 lb bag | Units per sq ft |
|---|---|---|---|
| Modular brick | 36 | 27 | 6.86 |
| Queen brick | 34 | 25.5 | 5.76 |
| Utility brick | 25 | 18.75 | 3.0 |
| 8 in block (standard) | 12 | 9 | 1.125 |
| 12 in block | 11 | 8.25 | 1.125 |
The second table is an illustrative budget scenario, not verified current retail pricing. Enter a current supplier quote for the selected bag weight. Compare actual price per pound and handling needs before choosing a bag size.
| Product | Bag size | Illustrative price each |
|---|---|---|
| Type N mortar mix | 80 lb | $8 to $11 |
| Type S mason mix | 80 lb | $9 to $13 |
| Mortar mix | 60 lb | $7 to $9 |
| Blended repair mortar | 40 lb | $9 to $14 |
| Type S mason mix (pallet, 56 bags) | 80 lb | $480 to $650 |
Example Problems
Example 1: Bags from a brick count.
For an arithmetic example, assume a product yield of 36 modular bricks per 80 lb bag, 500 bricks and a 10 percent extra allowance. Enter these assumptions explicitly, then divide and round up:
B = roundup(500 * 1.10 / 36) = roundup(15.3) = 16 bags. At $9.50 a bag that is about $152 in mortar.
Example 2: Bags from wall area.
For another arithmetic example, use a net wall 20 ft long and 8 ft high, nominal 8 × 16 inch block faces (1.125 units/ft²), an explicitly assumed yield of 12 units per 80 lb bag and a 10 percent extra allowance:
N = (20 * 8) * 1.125 = 180 blocks, so B = roundup(180 * 1.10 / 12) = roundup(16.5) = 17 bags.
Frequently Asked Questions
How many bags of mortar do I need for 100 blocks?
If your chosen product yields 12 blocks per 80 lb bag, 100/12 rounds up to 9 bags with no extra allowance, or 10 with 10% extra. Scaling that same assumed mix to 60 lb gives 9 blocks per bag: 12 bags without extra allowance or 13 with 10% extra. Use your actual product yield.
How many bricks does an 80 lb bag of mortar lay?
Coverage depends on product, brick size, joint thickness and application. The QUIKRETE Mortar Mix 1102 data sheet lists up to 37 standard bricks per 80 lb bag. Treat published coverage as a product-specific estimate and allow for job losses.
Should I buy 60 lb or 80 lb bags?
An 80 lb bag contains one-third more mix by weight than a 60 lb bag. Compare actual price per pound, product yield and safe handling requirements. The calculator scales the entered reference yield by selected bag weight for the same mix; this is a planning estimate.
