Build a full unit schedule for your wall. Choose an Australian masonry unit or enter your own, add bond beams and openings, and this free calculator counts full, half and lintel units, with mortar, grout, wall weight and a drawing of your wall.
The calculator did not load. Refresh the page to try again.
:
| Unit | Code | Qty | Each | Total |
|---|
Quantities include your waste allowance. Check codes against your supplier's list.
Units To Buy
0units
Mortar And Grout
Weight
Your Prices
| Unit | Per m² | Units | Wall Weight |
|---|
This compares quantities only. The unit must suit your design.
A masonry wall is rarely built from one kind of unit. You need full units, half units at the ends, and often bond beam or lintel units as well, each with its own code, weight and pallet size. This concrete masonry unit calculator builds that full schedule. It handles Australian blocks, half-height and solid units, and any custom unit you enter.
If you just want a quick count of standard blocks, with a course plan, footing and control joints, the Concrete Block Calculator is simpler. This page goes further into unit types, bond beams and weight. For steel in the wall, use the Reinforcing Steel Calculator.
A concrete masonry unit, or CMU, is a precast building unit made to be laid by hand in mortar. One American maker defines a concrete block as a unit made from portland cement and suitable aggregates, with or without other materials. The term CMU is common in American plans. Australians are more likely to say concrete block, besser block or masonry block, but the Concrete Masonry Association of Australia uses concrete masonry in its own name, and you will meet the term in specifications.
A masonry unit is more than a block with holes in it. Each unit is shaped for a job. Some carry steel, some finish an end, some sit over an opening, and some allow for movement. That is why a real order lists several codes rather than just a block count.
Compared with a poured concrete wall, masonry needs no formwork, and it goes up one course at a time. The units themselves form the faces of the wall, and the cores can take steel and grout. That makes it popular for retaining walls, garages, sheds, boundary walls and commercial buildings. The trade-off is labour, and a need to plan around the unit's fixed size.
Australian units follow a simple coding system, set out in the CMAA handbook. The first two digits give the nominal width, and the numbers after the point give the unit type. So 20.01 is a 200 series standard block, and 15.12 would be a 150 series lintel block.
| Code Ending | Unit | Example |
|---|---|---|
| .01 | Standard full block | 20.01 |
| .02 | Three-quarter length | 15.02 |
| .03 | Half length | 20.03 |
| .04 | Quarter length | 20.04 |
| .12 | Lintel block | 20.12 |
| .20 | Knock-out bond beam | 20.20 |
| .09 and .10 | Control joint blocks | 20.09, 20.10 |
Makers do not always agree. BCP's 2024 brochure, for example, uses 15.07 for a 150 series half block, 20.48 for an H-block, and lists 20.12 as both bond beam and lintel. It also uses .31 for solid blocks, .42 for recessed head blocks and .71 for half-height blocks. So check codes against your own supplier's list before you send an order. The schedule in the calculator uses the BCP codes, and it is a starting point.
Here is what each main unit does on a wall.
The calculator counts full, half and bond beam or lintel units, since those three make up most orders. Ask your supplier about the rest. Your plans may also call for H-blocks in reinforced walls. If so, count them in place of full units at each bar position.
These sizes and weights are from BCP's 2024 masonry brochure, and they are the figures the calculator starts from. Sizes are shown as length × height × width.
| Unit | Size | Weight | Per Pallet |
|---|---|---|---|
| 10.01 hollow | 390 × 190 × 90 mm | 10.1 kg | 195 |
| 15.01 hollow | 390 × 190 × 140 mm | 9.3 kg | 144 |
| 20.01 hollow | 390 × 190 × 190 mm | 11.3 kg | 108 |
| 30.01 hollow | 390 × 190 × 290 mm | 16 kg | 72 |
| 15.71 half height | 390 × 90 × 140 mm | 6 kg | 240 |
| 20.71 half height | 390 × 90 × 190 mm | 6.5 kg | 180 |
| 10.31 solid | 390 × 190 × 90 mm | 13.3 kg | 156 |
| 15.31 solid | 390 × 190 × 140 mm | 20.9 kg | 96 |
| 20.31 solid | 390 × 190 × 190 mm | 24 kg | 72 |
| 20.03 half | 190 × 190 × 190 mm | 8.3 kg | 180 |
| 20.12 bond beam | 390 × 190 × 190 mm | 19.5 kg | 90 |
| 15.12 bond beam | 390 × 190 × 140 mm | 15.6 kg | 120 |
Weights differ between makers. Apex Masonry, for example, says its standard block weighs 11.5 kg. Midland Brick lists a 15.31 solid block at about 10 kg, which is far below the 20.9 kg shown above, and it shows that the same code does not mean the same product. The 15.01 weight above is also lighter than the 10.01, which is what the brochure says. Pallet counts vary too. Before you plan a crane lift, get the weight of your actual block.
The CMAA handbook lists standard widths of 100, 120, 150, 200 and 300 mm. Not all of them are stocked everywhere, so ask early if your plan uses an unusual size.
Any concrete masonry unit calculator is built on one idea. Each unit takes up its own face size, plus one joint in each direction.
| Unit Face | Joint | Module | Units Per m² |
|---|---|---|---|
| 390 × 190 mm | 10 mm | 400 × 200 mm | 12.5 |
| 390 × 90 mm | 10 mm | 400 × 100 mm | 25 |
| 290 × 190 mm | 10 mm | 300 × 200 mm | 16.7 |
| 190 × 190 mm | 10 mm | 200 × 200 mm | 25 |
| 230 × 162 mm | 10 mm | 240 × 172 mm | 24.2 |
| 230 × 76 mm | 10 mm | 240 × 86 mm | 48.4 |
The first two rows match BCP's published 12.5 and 25 per m². The width of the unit does not change these numbers, because it is the face that counts. A 100 series wall and a 300 series wall take the same number of units per m², although they differ greatly in weight and grout.
For a straight wall, the calculator goes further than this formula. It counts each course in half-unit steps, then lays alternate courses with half units at the ends. That gives you a closer count of each unit type.
A unit schedule is the list you send to the supplier. It has one line for each unit type, with a code and a quantity. The calculator works it out in this order.
Each opening's lintel is counted with 200 mm of bearing on each side. That is our planning figure, because the real bearing comes from your design. Four Walls counts units around the centre line, and it adds half units only at openings, since corners stagger the joints for you.
The table in your results also shows each unit's weight, so you can see which line is the heaviest. A wall with a lot of bond beam units can weigh more than you would expect from the block count alone. That is useful to know before you book a delivery.
A bond beam is a horizontal reinforced band inside a wall. It ties the wall together, and in many designs it also carries roof or wind loads. A lintel does a similar job over an opening. Both use open-topped units, so bars and grout can sit in a channel.
The CMAA handbook gives the following for its 200 series examples.
| Item | Unit | Grout |
|---|---|---|
| Bond beam, 200 × 200 mm | Knock-out 20.20 | About 0.025 m³ per metre |
| Lintel, 200 × 400 mm | Lintel 20.12 | About 0.042 m³ per metre |
The handbook also describes two N12 horizontal bars in lintel blocks above each opening, and around the top course, as a minimum for its walling example. Your plans take priority. The calculator uses the 0.025 m³ per metre figure for one course, scaled to the unit width. So a 140 mm bond beam takes about 0.018 m³ per metre.
BCP lists a lower fill of 0.005577 m³ per 20.12 unit, which is about 0.014 m³ per metre. The difference may reflect the unit's shape, so treat grout as a rough figure and allow a margin. Choose No Top Bond Beam if your wall does not have one, and use Extra Bond Beam Courses for any others. The calculator puts all of them at the top of the wall for counting, but your design will set their real heights.
Bond beams and lintels must be fully grouted, with the steel in the right place, and that takes planning. The Concrete Grades Explained guide covers concrete grades, although your design will name the grout.
Each example uses 20.01 hollow units with 5% waste unless noted, and BCP weights.
With no bond beam, the schedule is 92 full and 7 half units, or 99 in all. The units weigh about 1,098 kg, and the wall takes about 10 bags of 20 kg premix mortar.
Now it is 77 full, 5 half and 16 bond beam units, or 98 in all. There is one less unit, but the units weigh 1,224 kg, because a bond beam unit is much heavier. It also needs about 0.16 m³ of grout.
The wall has 9 courses. The schedule is 206 full, 9 half and 27 bond beam units, with 24 bags of mortar and 0.19 m³ of bond beam grout.
At 2.4 m high, with one 0.9 m by 2 m door, a top bond beam and 50% core fill, the wall covers 17.4 m². The schedule is 194 full, 21 half and 26 bond beam or lintel units. Core fill comes to 0.76 m³, and bond beam grout to 0.24 m³. The wall works out to about 319 kg per m², or about 6.8 kN per metre on the footing.
With 2.4 m high walls, one 2.4 m by 2 m door and a top bond beam, the schedule is 491 full, 11 half and 59 bond beam or lintel units. That is 561 units, or about 6 pallets.
The same 6 m by 1.2 m wall in 20.71 units takes 12 courses, with 183 full and 13 half units. That is about twice the unit count of the first example, and it uses about 16 bags of mortar rather than 10.
Six piers, 1.8 m high, with 2 units per course, take 9 courses. That is 108 units, or 114 with waste. Piers are slender, so have the size and steel designed.
Masonry is heavy, and this concrete masonry unit calculator shows that weight in two ways: kilograms per square metre of wall, and kilonewtons per metre along the footing. The table below uses BCP unit weights, plus our planning figures for mortar at 2,000 kg per m³ and core fill at 2,400 kg per m³.
| Unit | Unfilled | Fully Core Filled |
|---|---|---|
| 10.01 hollow | 158 kg/m² | Not usually filled |
| 15.01 hollow | 148 kg/m² | 277 kg/m² |
| 20.01 hollow | 173 kg/m² | 372 kg/m² |
| 30.01 hollow | 231 kg/m² | 663 kg/m² |
| 20.71 half height | 215 kg/m² | – |
| 15.31 solid | 293 kg/m² | Solid |
| 20.31 solid | 331 kg/m² | Solid |
So an unfilled 20.01 wall 2.4 m high puts about 4.1 kN on every metre of footing, and a fully filled one puts about 8.8 kN. This counts the wall alone. Your engineer has to add roof loads, wind, soil pressure and more. It is a useful number for a first talk with your engineer, not a design.
Weight also matters for the delivery. A full pallet of 108 units at 11.3 kg is about 1,220 kg. A pallet of 90 bond beam units at 19.5 kg is about 1,755 kg. Check that the truck, the crane and the ground can take it. For the footing itself, use the Concrete Footing Calculator.
Core filling means pouring grout into the hollow cores around the steel. The calculator uses the CMAA handbook rates.
| Unit | Per m² Of Wall | Per Unit |
|---|---|---|
| 15.01 | 0.054 m³ | 0.0043 m³ |
| 20.01 | 0.083 m³ | 0.0066 m³ |
| 30 series | 0.180 m³ | 0.0144 m³ |
Choose 25%, 50% or 100% to match your plan. The calculator counts no core fill for 100 series, half-height, solid or custom units. Its grout figures include your waste allowance, and it adds bond beam grout on top as a separate line.
The handbook says core fill grout should be at least 12 MPa and preferably 20 MPa, with at least 300 kg of cement per m³ and 10 mm aggregate, at a pouring consistency. Ask your supplier for a core fill mix, and order it in m³ using the Concrete Supply Calculator. For a small fill, see the Concrete Bag Calculator. Check for fallen mortar before you pour. That is what cleanout units are for, since droppings can block cores and leave bars without cover.
The CMAA handbook gives 1 m³ of mortar for about 800 standard blocks, and Cement Australia says a 20 kg bag of its Trade Mortar lays about 10 blocks. For other units, the amount changes with the length of joint per square metre, so the calculator scales it.
A standard unit has 7.5 m of joint per m². A half-height unit has 12.5 m, so it takes about two-thirds more mortar. This scaling is our planning method, and it does not allow for the wider full bed used on solid units. The calculator therefore treats mortar as a rough figure.
The handbook also notes that hollow blocks use face-shell bedding, with mortar on the face shells and perpends only, and not the webs. It says that raked joints should never be used with hollow blocks that will not be rendered. Mortar classes M3 and M4 are listed in the handbook, and your plans should name the class for your site.
If you see a plan or a video calling for 8 × 8 × 16 CMU, it means a nominal size in inches. Angelus Block explains that nominal dimensions equal the specified dimensions plus the mortar joint. A US unit is therefore about 7⅝ × 7⅝ × 15⅝ inches, or about 194 × 194 × 397 mm.
| Item | US 8 × 8 × 16 CMU | Australian 20.01 |
|---|---|---|
| Actual size | About 397 × 194 × 194 mm | 390 × 190 × 190 mm |
| Joint | 3/8 in, about 9.5 mm | 10 mm |
| Module | 406.4 × 203.2 mm | 400 × 200 mm |
| Units per m² | About 12.1 | 12.5 |
| Units per ft² | 1.125 | About 1.16 |
The difference looks tiny, but the modules do not line up. Over 15 units, the US wall runs about 96 mm longer. So you can't swap a US drawing to Australian units by matching the sizes. Convert the wall length and height first, then count Australian units. If you want a US unit for a comparison, enter it as a custom unit. American plans also use different steel, grout and code rules, so have them checked. For unit conversions, try the Concrete Cubic Foot Calculator.
In this concrete masonry unit calculator, choose Custom Unit for anything not on the list, such as a concrete brick, a feature block, a retaining wall unit laid in mortar, or a supplier's own product. Enter the length, height, width and joint, plus the weight and pallet count if you have them. The calculator then works out the module, units per m², and courses.
For a 230 by 76 mm face with a 10 mm joint, the module is 240 by 86 mm, so a square metre takes 48.4 units. A 10 m² wall takes 485 units, or 510 with 5% waste. If you leave the weight blank, the wall weight is hidden, and no half or bond beam unit is named. Custom units get no core fill, because it depends on the shape.
Dry-stacked or interlocking retaining units work differently, as they usually have no mortar joint and may need a set-back. Enter a joint of 0 for a rough count, then follow the maker's guide. Any retaining wall needs proper design, and often a permit.
Australian makers commonly state that their units are made to AS/NZS 4455.1. Apex Masonry says its grey blocks are manufactured in accordance with AS/NZS 4455.1:2008 and tested under AS 4456:2013, and Urbanstone states much the same. Design is covered by AS 3700, and the CMAA handbook also refers to AS 4773 for masonry in small buildings. Your engineer or certifier will confirm which standards apply.
Strength depends on the product. Midland Brick lists a mean characteristic unconfined compressive strength above 12 MPa for one solid block. Apex says its high-strength blocks are tinted for identification, with test certificates available for extra-strength blocks. In the US, Angelus notes that ASTM C90 is the matching specification for loadbearing units.
Ask for the data sheet if your engineer has specified a strength, and don't assume two blocks that look the same perform the same. Keep the delivery dockets in case your certifier asks for them.
Masonry is often chosen for fire and noise separation, such as boundary walls and walls between units. The numbers depend on the product and the wall, so the calculator does not attempt them. As an example of what makers publish:
If a fire or sound rating is part of your approval, get the figure from the maker and have a certifier confirm it. Slenderness, restraint, core fill and render can all change the result, and any gaps or penetrations matter too.
Enter your prices under Prices, and the calculator adds up each line of the schedule. These list prices give you an idea of the range.
| Unit | List Price Each | Per m² Of Wall |
|---|---|---|
| 100 series 10.01 | $3.81 | About $48 |
| 150 series | $4.24 | About $53 |
| 200 series 20.01 | $5.01 | About $63 |
| 300 series | $7.49 | About $94 |
These are from a National Masonry price list dated 1 September 2026, for delivered orders of 3 pallets or more in Brisbane and the Gold Coast. Retail prices can be much higher, so get a quote for your unit and your area. Special units usually cost more than full units, and a part pallet may cost more again.
Materials are only part of the job. Laying, steel, core filling, render and footings all add up. For a full budget, see the Concrete Block Calculator and the Concrete Cost Calculator.
The calculator rounds up to whole pallets using the pallet counts in your unit data, and it adds up the part pallets of each unit type. Treat that number as a guide, because suppliers pack units in their own way and some will not split a pallet.
Waste starts at 5% here, which is our planning allowance for a clean, modular wall with the right special units. Use 10% if your wall has a lot of cutting, corners or openings. Unused full pallets can sometimes go back to the supplier, so ask about their returns policy when you order.
Unbraced walls can fall without warning, so prop them until they are finished. Lift heavy units safely, and use mechanical help for bond beam units. Cutting masonry makes dust containing silica, so read Safe Work Australia's silica guidance and use suitable controls.
When you are done, download the PDF from this concrete masonry unit calculator and send it to your supplier. It lists every unit type, so nothing gets left out of the order.
It is a manufactured block made from cement, aggregates and water, laid in mortar to build walls. The short name is CMU. In Australia most people say besser block or concrete block, and the units are named by series and code.
12.5 for a standard 390 mm by 190 mm unit with a 10 mm joint. Half-height units need 25 per m². For any other unit, divide 1 by (length + joint) × (height + joint), all in metres.
The first two digits give the nominal width, so 20 means the 200 mm series. The digits after the point give the type. In the CMAA system, .01 is a standard block and .03 is a half block.
Actual size is the measured size of the unit. Nominal size adds the mortar joint. A 20.01 unit is 390 by 190 by 190 mm actual, and 400 by 200 by 200 mm nominal.
One course of bond beam units for every bond beam along the wall, plus lintel units over each opening. A 6 m wall takes 15 units in a top bond beam, before waste.
Both form a channel for bars and grout. In the CMAA system, 20.12 is a lintel block, while 20.20 is a knock-out bond beam. Some suppliers list one unit for both jobs, so check your plan and your supplier's list.
One 2024 Australian brochure lists a 20.01 hollow block at 11.3 kg, a 20.31 solid block at 24 kg and a 20.12 bond beam unit at 19.5 kg. Weights vary by maker.
About 173 kg per m² for an unfilled 20.01 wall with mortar, using our planning figures. Fully core filled, it is about 372 kg per m².
An unfilled 20.01 wall 2.4 m high is about 4.1 kN per metre. Fully core filled, it is about 8.8 kN per metre. That is the wall alone, so your engineer must add roofs, floors and other loads.
They are close but not the same. A US 8 by 8 by 16 CMU is about 397 by 194 by 194 mm actual, so it takes about 12.1 units per m², against 12.5 for a 390 by 190 mm unit.
Yes. Choose Custom Unit and enter its size and joint. A 230 by 76 mm face with a 10 mm joint works out to about 48.4 units per m².
Makers commonly state compliance with AS/NZS 4455.1 for masonry units. Design and construction are covered by AS 3700, and by AS 4773 for small buildings. Your engineer or certifier can confirm what applies.
It varies by product and maker, so check the data sheet. One Australian product page lists a characteristic unconfined compressive strength above 12 MPa for a solid block.
Many are, but the rating depends on the unit, thickness, core fill, render and how the wall is restrained. Use the maker's fire data or an engineer, as the calculator does not assess it.
Hollow units are lighter and can take steel and core fill, so they suit most reinforced walls. Solid units are much heavier and suit certain details. Follow your plans.
No. It counts units and materials only, and your numbers stay in your browser. Reinforcement, footings and approvals must follow your plans, engineer and council.
Figures reviewed November 2026. Sources: Concrete Masonry Association of Australia, BCP, National Masonry, Apex Masonry, Midland Brick, Urbanstone, Cement Australia and Angelus Block, linked in the sections above. Results are planning estimates, so confirm your final quantity, specification and price with your supplier, engineer, council and the people responsible for your project. See our Disclaimer and Calculator Methodology.