Concrete block and brick calculator
Enter the wall and what it is built of. This counts the blocks or bricks to order with waste, the bags of mortar at your bag's own yield, and the vertical rebar at the spacing on your drawing.
Above the footing
0 if there are none
Broken and cut units, often 5–10%
Printed on the bag — this default is a typical 80 lb premixed bag, not a standard
The spacing on your drawing
Blocks to order
114blocks
Bags of mortar
9
Wall area
96 sq ft
Courses
6
Where the number comes from
- Gross wall area
- 96 sq ft
- Wall to layAfter 0 sq ft of openings
- 96 sq ft
- Blocks per sq ft144 sq in over a 16" x 8" nominal face, joint included
- 1.125
- Blocks in the wall
- 108
- Ordered with wastePlus 5%, rounded up
- 114
- Mortar108 laid at 13 a bag — waste not included
- 9 bags
Vertical rebar
- BarsOne at each end, then 48" apart — no gap over 48"
- 7 at 4 ft
- Total length
- 28 ft
- 20 ft sticks5 bars cut from each
- 2
Counts the bars in the wall only. The lap onto the dowels coming up out of the footing, the extra bar each side of an opening, the bar size and which cores are grouted come from the drawing, not from this page.
Retaining and load-bearing walls
This counts material; it does not design a wall. A wall holding back soil, carrying a floor or a roof, or standing more than a few feet high needs its footing, reinforcement and grout specified by an engineer or by the building code your department enforces — and most departments want a permit before the first course goes down. Ring them before you order.
Where to buy this
- 114 blocksHome DepotLowe's
- 9 bags of mortarHome DepotLowe's
- 2 x 20 ft rebarHome DepotLowe's
The rebar search is for the material, not a bar size we worked out for you — that comes from your drawing.
Plain search links, nothing sponsored. Prices and stock are the shop's, and a local lumberyard will usually beat both on solid stock.
About block and brick walls
- How many concrete blocks per square foot of wall?
- 1.125 for standard 8" x 8" x 16" block — 112.5 for every 100 square feet of wall. A block is 7 5/8" x 15 5/8" actual, and adding one 3/8" mortar joint makes a nominal 8" x 16" face of 128 square inches, which goes into a 144 square inch foot 1.125 times. It is the same count for 6", 8" and 12" thick block, because thickness is not on the face. Add waste on top for broken and cut units.
- How many bricks per square foot?
- 6.75 modular bricks per square foot with 3/8" joints, or 675 per 100 square feet — the Brick Industry Association's own figure. A modular brick is 7 5/8" x 2 1/4" actual, laid on an 8" x 2 2/3" module: three courses to 8" and one and a half bricks to the foot. Queen, king and Norman sizes lay a different number per foot, so check which one the yard is quoting.
- How many bags of mortar do I need?
- The number printed on your bag decides it, which is why the calculator asks for it rather than assuming. Premixed 80 lb bags of mortar mix commonly print something around 13 block or 40 brick a bag, and those are this page's starting values — but yield changes with the product, whether you buy premixed mix or masonry cement to add your own sand to, how full the head joints are and how much drops off the board. Buy a bag or two over; an open bag keeps a while, and running out mid-course leaves a cold joint.
- How far apart does the rebar go in a block wall?
- Whatever the drawing or the engineer says — bar size, spacing, the lap onto the footing dowels and which cores get grouted all depend on the wall's height, what it holds back and the local code, and this page does not choose them. It counts what you enter: at 48" on centre, for example, a 24 ft wall takes 7 vertical bars, one at each end and none further apart than 48". Add a bar each side of any door or window.
- Do I need an engineer for a block wall?
- For a retaining wall, a wall carrying a floor or a roof, or anything more than a few feet tall, usually yes, and almost always a permit. The block count on this page is the same either way; what changes is the footing, the reinforcement, the grout and the drainage behind a retaining wall, and those are what fail. A short freestanding garden wall is the case a homeowner builds without drawings, and even that is worth a call to the building department first.
You might also need
- Concrete footings and slabsCubic yards for a run of post footings or a slab, and the bags of ready-mix that buys.
- Concrete screw lengthLength and embedment for a concrete screw, the bit that goes with it, and how deep to drill.
- Paint and finish coverageGallons from an area and a coat count, with the cans to buy for brush, roller or spray.