Brick Calculator
Buy 2414 bricks and 20 bags of mortar.
| Figure | Value |
|---|---|
| Gross wall area | 320 ft² |
| Net area to build | 320 ft² |
| Units per ft² face + 0.375 in joint each way | 6.857 |
| Exact count | 2,195 |
| With 10% waste | 2,414 |
| Mortar 8 bags per 1,000 units | 20 bags |
Counts use the face size plus one mortar joint in each direction, since every joint is shared between neighbours. A modular brick is 7⅝ × 2¼ in, so with a 3/8 in joint the module is exactly 8 × 2⅝ in and 144 ÷ 21 = 6.86 bricks per ft² — the familiar "about seven to the square foot". A nominal 8 × 16 in block module works out at exactly 1.125 per ft². Note the difference between nominal and actual sizes: the nominal size already includes the joint, which is why an 8 × 8 × 16 in block really measures 7⅝ × 15⅝. Mortar is a trade ratio and varies with joint width, unit absorption, and how much gets dropped — buy a bag more than the figure here. Not included: wall ties, reinforcement, lintels, flashing, weep holes, or the footing, all of which a structural wall needs.
Enter your wall size to find how many bricks or concrete blocks you need, plus mortar bags — using real face sizes and your joint width.
How to use this calculator
- Enter the wall length and height, or the total area if you already have it.
- Pick the unit. The list uses real face dimensions, not nominal names.
- Set the mortar joint — 3/8 in is standard and what modular sizing assumes.
- Deduct large openings like garage doors and picture windows. Small windows fall inside the waste factor.
- Set the waste factor: 10% typical, 15% for a cut-up wall, 5% for plain block work.
The formula
Module area = (Face length + Joint) × (Face height + Joint) · Units per ft² = 144 ÷ Module area
Units = Net wall area × Units per ft² × Waste · Mortar bags = Units × Bags per 1,000 ÷ 1,000
Worked example — a 40 × 8 ft brick wall
Modular brick, 3/8 in joint, no openings, 10% waste.
- Wall area: 40 × 8 = 320 ft²
- Module: (7.625 + 0.375) × (2.25 + 0.375) = 8 × 2.625 = 21 in²
- Bricks per ft²: 144 ÷ 21 = 6.857
- Exact count: 320 × 6.857 = 2,195 bricks
- With 10% waste: 352 ft² × 6.857 = 2,414 bricks
- Mortar: 2,414 × 8 ÷ 1,000 = 20 bags
Notice that waste is applied to the area and then converted, rather than adding 10% to the rounded brick count. The two differ by a brick or two, and applying it to the area is the one that stays consistent when you change joint width or unit size.
Why nominal sizes are smaller than they sound
A modular brick is called 8 inches long but measures 7⅝. An 8 × 8 × 16 inch block measures 7⅝ × 15⅝. This is not a manufacturing tolerance — it is deliberate, and it is what makes masonry lay out cleanly.
The nominal size includes the mortar joint. Add a 3/8 inch joint to a 7⅝ inch brick and you get exactly 8 inches of wall per brick. That means a 16-foot wall is exactly 24 bricks long, three courses of modular brick rise exactly 8 inches, and a brick course lines up with a block course every three rows. Every dimension in masonry works because the joint was designed into the unit size.
The practical consequence: change the joint width and you break the modularity. A 1/2 inch joint makes the module 8.125 inches, and suddenly nothing lands on a clean dimension.
Units per square foot by type
| Unit | Actual face | Per ft² at 3/8 in joint | Mortar bags / 1,000 |
|---|---|---|---|
| Modular brick | 7⅝ × 2¼ in | 6.86 | 8 |
| Queen brick | 7⅝ × 2¾ in | 5.76 | 7 |
| King brick | 9⅝ × 2⅝ in | 4.80 | 6 |
| Utility brick | 11⅝ × 3⅝ in | 3.00 | 5 |
| Concrete block, 8 in | 15⅝ × 7⅝ in | 1.125 | 28 |
Larger units mean fewer pieces and less labour, which is most of why they exist. Note that mortar per 1,000 units runs the other way for block: a block has far more joint length relative to its count, so 1,000 blocks take three and a half times the mortar of 1,000 modular bricks — even though they cover eight times the wall.
Buy it all at once
Brick is fired from natural clay in batches, and colour varies between runs in a way that is obvious on a finished wall. Order the whole job from one run, and blend from several pallets as you lay rather than working through one pallet at a time — that spreads any variation across the wall instead of leaving a visible band.
This is also why the waste factor is not optional. Brick arrives chipped, breaks when cut, and gets dropped. Running short means either a visible colour change or a delay while a matching batch is found.
What this calculator does not include
- The footing. Masonry is heavy and needs a proper foundation below the frost line.
- Wall ties for veneer — typically one per 2.67 ft² of wall, anchoring the brick back to the structure.
- Lintels over every opening, sized to the span.
- Flashing and weep holes. Brick veneer is not waterproof; water gets behind it and must have a drainage path out. Missing weeps is a leading cause of masonry wall failure.
- Reinforcement and grout for structural block walls, and control joints to manage cracking.
A load-bearing or retaining masonry wall needs an engineer's design. This calculator estimates material quantities, not structural adequacy.
How we calculate this
Units per square foot come from the module — the unit's actual face size plus one mortar joint in each direction — because every joint is shared between neighbouring units. A modular brick face of 7⅝ × 2¼ in with a 3/8 in joint gives an 8 × 2⅝ in module, 21 in², and 144 ÷ 21 = 6.857 bricks per ft². A nominal 8 × 16 in block module is exactly 128 in², giving precisely 1.125 per ft². Waste is applied to the wall area before the count, not to the rounded count afterwards. Mortar uses the published trade ratios per 1,000 units, which differ sharply between brick and block because block has far more joint per unit of wall.
Sources
Frequently asked questions
How many bricks per square foot?
About 6.86 modular bricks per square foot of wall face with a standard 3/8-inch mortar joint — the figure most people round to 7. A modular brick's face is 7⅝ by 2¼ inches, and adding the joint makes the repeating module exactly 8 by 2⅝ inches, which is 21 square inches. Divide 144 by 21 and you get 6.86.
How many bricks do I need for a 40 by 8 foot wall?
That is 320 square feet, so 2,195 modular bricks exactly. Adding the standard 10% waste factor for cuts and breakage brings it to 2,414, plus about 20 bags of mortar mix. Order the full amount at once — brick colour varies between production runs and a later top-up may not match.
How many concrete blocks per square foot?
Exactly 1.125 standard 8 by 8 by 16 inch blocks per square foot. The nominal 8 by 16 inch face already includes the 3/8-inch mortar joint, so the module is a clean 128 square inches and the maths comes out exact. That means 1,125 blocks per 1,000 square feet of wall.
What is the difference between nominal and actual brick size?
The nominal size already includes the mortar joint; the actual size is the brick itself. A modular brick is nominally 8 by 2⅔ inches but actually measures 7⅝ by 2¼. Similarly an 8 by 8 by 16 inch block really measures 7⅝ by 15⅝. This is deliberate — it means bricks and blocks lay out on clean whole-inch modules, so a 16-foot wall is exactly 24 modular bricks long.
How much mortar do I need for 1,000 bricks?
Roughly 7 to 8 bags of mortar mix for modular brick with a 3/8-inch joint, and about 28 bags per 1,000 for concrete block, which has far more joint area per unit. These are trade ratios and they vary with joint width, how absorbent the units are, and how much gets dropped off the board — buy at least one bag more than the calculation says.
What size mortar joint should I use?
3/8 inch is the standard and what nominal sizing assumes. A 1/2-inch joint is used on some block work and older restoration. Going thinner than 1/4 inch does not leave enough mortar to bed properly, and anything much wider weakens the wall and throws your coursing off — the whole point of modular sizing is that the joint width makes the numbers come out even.
Should I deduct windows and doors from a brick estimate?
Yes, for anything large. A single small window in a big wall falls within the waste factor, but a garage door or a picture window is worth deducting — several hundred bricks. Note that you still cut brick around every opening, so the material saved is less than the opening's area suggests, which the waste factor accounts for.
What waste factor should I use for brick?
10% for a straightforward wall. Go to 15% for a wall with lots of corners, openings, or an intricate pattern, and for any veneer where you are cutting around windows. Concrete block can run lower, around 5%, because blocks are larger, break less, and are more often laid in simple runs. Never order exactly the calculated count — brick breaks in transit and on site.