Mortar Calculator for Blocks
Work out bags of mortar mix for a block wall.
Your result
Enter your numbers and press the button. Your result appears here.
Quikrete says an 80 lb bag of Mortar Mix lays up to 13 standard 8×8×16 blocks, and a 60 lb bag about 9.
How it works
Bags = blocks × (1 + extra) ÷ blocks per bag.
Example: 100 blocks with 10% extra take 9 bags of 80 lb mortar mix.
Standard block sizes
| Nominal | Actual | Blocks per 100 ft² of wall |
|---|---|---|
| 4×8×16 | 3⅝ × 7⅝ × 15⅝ in | 112.5 |
| 6×8×16 | 5⅝ × 7⅝ × 15⅝ in | 112.5 |
| 8×8×16 | 7⅝ × 7⅝ × 15⅝ in | 112.5 |
| 12×8×16 | 11⅝ × 7⅝ × 15⅝ in | 112.5 |
Nominal sizes include a ⅜ in mortar joint.
Common questions
How many blocks per square foot?
A standard block with an 8×16 in face covers 1.125 blocks per square foot, or 112.5 blocks per 100 square feet.
How many blocks does a bag of mortar lay?
Quikrete lists its 80 lb Mortar Mix at up to 13 standard 8×8×16 blocks and its 60 lb bag at about 9.
Do I need rebar in a block wall?
Structural and retaining walls usually need vertical rebar and grout-filled cores. Follow your plans and local code.
Sources
- Quikrete 80 lb Mortar Mix (blocks per bag), Lowe's listing: https://www.lowes.com/pd/QUIKRETE-80-lb-Gray-Type-Type-S-Mortar-Mix/5002094147