How Much Mortar for a Brick Wall
This free brick mortar calculator answers exactly that: enter your wall's length and height and it estimates the total mortar volume in cubic feet, plus how many 60-lb or 80-lb bags you need to buy — with a waste allowance included. Results update instantly as you type.
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How to use this calculator
If you're planning a brick project and wondering how much mortar for a brick wall you actually need, start with the wall's length and height in feet. The calculator turns that area into a mortar volume in cubic feet, then divides by your bag's yield to tell you how many bags to buy — all rounded up, with your waste allowance folded in.
Choose single wythe for a one-brick-thick wall (garden walls, veneers, partitions) or double wythe if the wall carries structural load — a double wythe needs roughly twice the mortar. Then pick your brick type: standard and modular bricks use about the same mortar per square foot, while taller jumbo brick lays fewer courses and needs roughly 12% less. The standard 3/8 in mortar joint is the default, but you can widen or narrow it to match your spec.
Finally, pick your bag size (60-lb bags yield about 0.75 cu ft of mixed mortar, 80-lb bags about 1.0 cu ft) and keep the default 10% waste allowance, which covers mortar dropped on the ground, re-tempered batches, and over-filled joints. Need the brick count instead? Our Brick Wall Calculator estimates bricks per wall — this tool focuses on the mortar side.
How it works
The core rule is a planning estimate: about 0.065 cubic feet of mortar per square foot of single-wythe wall built with standard brick and 3/8 in joints (about 6.5 cu ft per 100 sq ft). That rate is then adjusted for your choices:
mortar (cu ft) = area × 0.065 × wythes × joint factor × brick factor
The joint factor comes from the geometry of the wall face: mortar volume follows the share of each square foot taken up by joints, so 1/2 in joints use about 27% more mortar than 3/8 in joints, and 1/4 in joints use about 30% less. The brick factor reflects course count — taller jumbo brick means fewer courses and roughly 12% less mortar than standard brick, while modular brick rates the same as standard. Double wythe simply doubles the single-wythe figure.
Bags are the mortar volume divided by the bag yield, rounded up:
bags = ceil(mortar cu ft ÷ bag yield), with 0.75 cu ft per 60-lb bag and 1.0 cu ft per 80-lb bag.
The waste allowance is applied to the volume, and the recommended order is rounded up from that waste-inclusive figure: for example, a 20 ft by 8 ft wall is 160 sq ft → 160 × 0.065 = 10.4 cu ft → 10.4 ÷ 0.75 = 13.87 → 14 bags of 60-lb; with 10% waste that's 11.44 cu ft → 16 bags to buy.
All figures are estimates. The 0.065 cu ft per sq ft rule assumes full joints; deeply raked or struck joints use less, and sloppy bedding uses more. Bag yields are approximate mixed volumes — confirm quantities with your mortar supplier before ordering.
Frequently asked questions
How much mortar do I need per square foot of brick wall?
A common planning figure is about 0.065 cubic feet of mortar per square foot of single-wythe wall built with standard brick and 3/8 in joints — roughly 6.5 cu ft per 100 sq ft. Treat this as an estimate: wider joints, taller (jumbo) brick, and double-wythe walls all shift the number, which is why the calculator above adjusts for them.
How many 60-lb mortar bags do I need for a 100 sq ft brick wall?
About 9 bags for the base estimate: 100 sq ft × 0.065 cu ft per sq ft = 6.5 cu ft of mortar, and each 60-lb bag yields about 0.75 cu ft, so 6.5 ÷ 0.75 = 8.67, rounded up to 9 bags. With a 10% waste allowance that's 7.15 cu ft, so plan on buying 10 bags. Enter your exact wall size in the calculator above for your own number.
Does mortar joint thickness change how much mortar I need?
Yes. Mortar volume follows the share of the wall face taken up by joints: 1/2 in joints use about 27% more mortar than 3/8 in joints on the same wall, while 1/4 in joints use about 30% less. The calculator scales the estimate from the joint width you select using that geometry.
How many 80-lb bags equal a 60-lb bag of mortar?
A 60-lb bag of mortar yields about 0.75 cu ft of mixed mortar, while an 80-lb bag yields about 1.0 cu ft — so one 80-lb bag covers roughly the same as one and a third 60-lb bags. For the same wall, expect to need about three-quarters as many 80-lb bags as 60-lb bags.