Mortar Calculator
Estimate the volume of wet mortar and number of 80 lb dry mix bags required for masonry projects using brick or concrete blocks.
Calculation Results
Estimated volume of wet mortar required to lay the specified masonry units.
Number of standard 80 lb bags of Type N/S dry mortar mix to purchase.
How This Calculator Works
To calculate mortar requirements:
- Enter the number of individual brick units to be laid (leave at 0 if you are only using concrete blocks).
- Enter the number of standard concrete blocks to be laid (leave at 0 if you are only using bricks).
- Enter a waste buffer factor to cover spillage and trowel drops (10% is standard).
- The calculator determines total wet volume and the number of 80 lb dry bags to purchase.
Formula & Calculations
Mortar requirements are estimated using standard trade yield ratios for standard 3/8-inch joints:
- Standard Bricks: Laying 1,000 standard bricks requires approximately
7.0cubic feet of wet mortar. - Concrete Blocks: Laying 100 standard concrete blocks (8"x8"x16") requires approximately
3.6cubic feet of wet mortar (or0.036cu ft per block).
The total volume is scaled with a waste allowance buffer (typically 10% to cover drop loss):
Volume = (Bricks × 0.007 + Blocks × 0.036) × (1 + Waste / 100)
Bag count is calculated based on the standard volumetric yield of one 80 lb bag of dry mortar pre-mix (approx 0.85 cubic feet of wet mortar paste):
Bags = ceil(Volume / 0.85)
Step-by-Step Calculation Examples
Common Masonry Construction Project
Estimating mortar volume and 80 lb bag counts required to lay 1,000 bricks and 500 concrete blocks with 10% waste.
- brick_count: 1000
- block_count: 500
- waste: 10
- mortar_volume: 27.50 cu ft
- bags_needed: 33
Frequently Asked Questions
What is the standard yield of an 80 lb bag of mortar mix?
A standard 80 lb bag of dry pre-blended mortar mix (such as Type N or Type S) yields approximately 0.85 cubic feet of wet mortar paste when mixed with water.
How many bags of mortar do I need for 100 blocks?
Laying 100 standard 8"x8"x16" concrete blocks typically requires about 3.6 cubic feet of wet mortar. This equates to approximately 4.5 bags (purchase 5 bags) of 80 lb mortar mix.
How many bags of mortar do I need for 1,000 bricks?
Laying 1,000 standard modular bricks with standard 3/8-inch joints requires approximately 7.0 cubic feet of wet mortar, which equates to about 8 to 9 bags of 80 lb mortar mix.
What type of mortar should I use for general masonry?
Type N mortar is the most common for residential brick and block walls. It is a medium-strength blend with high workability. Type S mortar has higher strength and is used for structural foundations or below-grade retaining walls.
Why does mortar require a waste margin?
Masonry involves a significant amount of "drop"—mortar that falls off the trowel or joints during scraping. An extra 10% allowance is standard to ensure you do not run short.