Brick Calculator

Estimate the bricks, mortar, cement and sand a brick wall needs.

Single or double walls, metric or imperial sizes, and twenty currencies at live rates.

Updated October 20, 2026

CreatorFrank Zhao

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Introduction

A brick wall is really three orders in one: the bricks, the mortar that beds and joints them, and the cement and sand that make that mortar. This calculator follows the same three steps. Describe the wall and the brick, and it returns how many bricks to order, how much wet and dry mortar the wall takes, how much cement and sand that mortar needs, and what the materials cost.

It is built for the moment a wall on a drawing or a garden plan has to become a shopping list: pricing a job, checking a builder's quote, or working out a weekend build before the merchant closes. The wall can be a single leaf or two leaves with insulation between them, the dimensions can be entered in metric, imperial or mixed units, and each price box has its own currency menu.

Two habits make the answers much more useful. First, feed it the net wall area: doors, windows and other openings are not entered separately, so take them out of the area before the count is made. Second, treat the two brick numbers as a pair — the wall needs one figure, but you order the other, because whole bricks are what arrive on the pallet.

43.3 bricks / m²

With a 200 × 100 mm brick and a 10 mm joint

8 length units

Including feet/inches and metres/centimetres

20 currencies

For the brick, cement and sand prices

Quick start

Choose the wall type

Single is one leaf of bricks. Double is two leaves with a cavity or insulation between them: the page treats it as two walls of the same size, so every brick and every litre of mortar is doubled. It is not a thicker brick, and it does not add the cavity itself.

Enter the wall

Type the wall length and height, or the area directly — any two of those three boxes determine the third. Use the net area, with openings already deducted, and make sure the height runs from the base of the wall to the top of the brickwork rather than to the underside of a roof.

Set the brick and the joint

The page opens with a 200 × 100 × 100 mm brick and a 10 mm joint, the common metric sizes. Replace them with the dimensions your merchant lists. Brick sizes exclude the mortar, and the joint is added to both the length and the height of each brick.

Add a brick wastage allowance

Five percent is loaded by default. Ten percent suits reclaimed or heavily cut bricks, and up to 20% is available where breakage is likely. The allowance is applied to whole bricks, on top of the rounded wall count.

Reveal the mortar and the costs

Tick Tick to see materials for your mortar to show the mortar groups. Choose the mix that matches the job, set the bag size and cement density that match what you buy, then enter the price of a brick, the price of a bag and the price of a unit of sand. Each price box has its own currency menu.

Work through a 10 m² wall

A single-leaf garden wall, 4 m long and 2.5 m high, is 10 m². With 200 × 100 × 100 mm bricks, a 10 mm joint and 5% wastage, the brick count works out like this:

a_{\mathrm{m}}

=

0.21 \times 0.11

=

0.0231\ \mathrm{m^2}

n_{\mathrm{b}}

=

\left\lceil \frac{10 \times 1}{0.0231} \right\rceil

=

\lceil 432.9 \rceil

=

433

n_{\mathrm{t}}

=

\left\lceil 433 \times 1.05 \right\rceil

=

\lceil 454.65 \rceil

=

455

The page returns 433 bricks needed and 455 bricks to order. Below that, the wall needs 0.134 m³ of wet mortar, which becomes 0.204 m³ dry and 0.224 m³ once a 10% mortar wastage is added. On the default 1:6 mix that is 0.0321 m³ of cement — 46.2 kg — and 0.192 m³ of sand, so one 50 kg bag covers it. At 1.20 per brick, 8.00 per bag and 25.00 per cubic metre of sand, the bricks cost 546.00, the cement 8.00, the sand 4.81, and the wall totals 558.81.

What to do with each number

Take the total bricks needed to the merchant, not the wall count. Use the total dry volume to buy the cement and sand, and use the bags of cement for the order, since that is how cement is sold. The wet volume is the figure that matters if you order ready-mixed mortar instead of mixing on site.

Calculation method

Every result on the page comes from the same two inputs: the net wall area and the brick-and-joint module. The rest is a chain of multiplication, two ceiling operations and one density conversion. Knowing where the ceilings sit explains most of the numbers that look surprising.

The module a brick really occupies

a_{\mathrm{m}}

=

(l + t)\,(h + t)

The joint is added to the brick on both dimensions, not once around its face. A 200 × 100 mm brick with a 10 mm joint therefore occupies $0.21 \times 0.11 = 0.0231\ \mathrm{m^2}$ , so a square metre of wall holds $1 / 0.0231 = 43.3$ of them. Without joints the same square metre would hold 50 bricks; the joint is why the answer is about 43, not 50.

The brick count, rounded twice

n

=

\frac{A_{\mathrm{wall}} \times k}{a_{\mathrm{m}}}

n_{\mathrm{b}}

=

\lceil n \rceil

n_{\mathrm{t}}

=

\lceil n_{\mathrm{b}}\,(1 + w_{\mathrm{b}}) \rceil

The wall type $k$ is 1 for a single leaf and 2 for a double wall, so a double wall simply doubles the count. The first ceiling turns the fractional count into whole bricks for the wall. The wastage allowance is then applied to those whole bricks and rounded up again, because the extra bricks are also ordered in whole units. That is why the order quantity is not the wall count plus exactly 5%.

The mortar the joints leave behind

V_{\mathrm{wet}}

=

A_{\mathrm{wall}}

\times

w

\times

k

\times

\left(1 - \frac{l\,h}{a_{\mathrm{m}}}\right)

The bracket is the share of the wall face that mortar fills: the wall face minus the brick faces sitting in it. Multiplied by the brick width — which is the thickness of the wall — and by the number of leaves, that share becomes a volume. It covers the bed joints and the head joints. It does not cover mortar dropped on the ground, a separate bedding layer under the first course, or cavity fill; the mortar wastage field is where site losses are handled.

Dry volume, the dry-to-wet ratio and mortar wastage

V_{\mathrm{dry}}

=

V_{\mathrm{wet}} \times r

V_{\mathrm{total}}

=

V_{\mathrm{dry}} \times (1 + w_{\mathrm{m}})

The dry mix is bulkier than the mortar it becomes: adding water lets the fine particles slide into the voids, so the wet volume is smaller than the dry volume it came from. The ratio is set to 1.52 and accepts values from 1.52 to 1.57, the range the page works to. The mortar wastage allowance then covers spillage and mixing losses, from 0% to 20%, with 10% loaded by default.

Splitting the dry volume into cement and sand

V_{\mathrm{c}}

=

V_{\mathrm{total}} \times \frac{c}{c + s}

V_{\mathrm{s}}

=

V_{\mathrm{total}} \times \frac{s}{c + s}

The mix menu sets the parts. A 1:6 mix has one part cement to six parts sand, so cement takes $1 / 7$ of the dry volume and sand takes the other $6 / 7$ . The parts are treated as volumes, which is how mortar is normally gauged on site.

From volume to a weight and a bag count

m_{\mathrm{c}}

=

V_{\mathrm{c}} \times \rho

n_{\mathrm{bags}}

=

\left\lceil \frac{m_{\mathrm{c}}}{m_{\mathrm{bag}}} \right\rceil

Cement is sold by weight, so the cement volume is multiplied by its density — 1440 kg/m³ is loaded as the default for dry cement, and the figure on your bag or data sheet is the better one — and then divided by the bag size, with the result rounded up. One kilogram over a whole bag is one more bag, which is why a small change of mix can move the order.

The cost of the three materials

C

=

p_{\mathrm{b}}\,n_{\mathrm{t}}

+

p_{\mathrm{bag}}\,n_{\mathrm{bags}}

+

p_{\mathrm{s}}\,V_{\mathrm{s}}

Bricks multiply the order quantity, cement multiplies whole bags, and sand multiplies the sand volume by its price per unit of volume. Cement plus sand gives the mortar cost, and bricks plus mortar gives the total cost of the wall. Each of those three prices can be entered in a different currency; the page converts them to one currency before adding.

What the page solves backwards

The wall, the mortar and the cement chain are all reversible. Enter a measured net area and the length or height follows; enter a wet volume, a dry volume, a cement volume or a cement weight and the page works back to the wall area that those materials would build. The rounded outputs — bricks needed, total bricks, bags of cement and the cost fields — are read-only, because a ceiling cannot be undone: many different walls can round to the same 455 bricks.

Symbols used on this page

A_{\mathrm{wall}}

Net wall area, length times height

L

Wall length

H

Wall height

l

Brick length

h

Brick height

w

Brick width, the thickness of the wall

t

Mortar joint thickness

k

Wall type: 1 for a single wall, 2 for a double wall

a_{\mathrm{m}}

Brick module area, one brick plus its joints

n

Fractional brick count before rounding

n_{\mathrm{b}}

Bricks needed for the wall

w_{\mathrm{b}}

Brick wastage allowance, as a fraction

n_{\mathrm{t}}

Total bricks to order, wastage included

V_{\mathrm{wet}}

Wet mortar volume the wall needs

r

Dry-to-wet volume ratio, 1.52 to 1.57

V_{\mathrm{dry}}

Dry mortar volume before the mortar wastage

w_{\mathrm{m}}

Mortar wastage allowance, as a fraction

V_{\mathrm{total}}

Total dry mortar volume, wastage included

c

Cement parts in the selected mix

s

Sand parts in the selected mix

V_{\mathrm{c}}

Volume of cement

V_{\mathrm{s}}

Volume of sand

\rho

Density of dry cement

m_{\mathrm{c}}

Weight of cement

m_{\mathrm{bag}}

Bag size of cement

n_{\mathrm{bags}}

Whole bags of cement to buy

p_{\mathrm{b}}

Price of one brick

p_{\mathrm{bag}}

Price of one bag of cement

p_{\mathrm{s}}

Price of sand per unit of volume

C

Total material cost of the wall

Choosing the mortar mix

The mix menu offers four volume proportions, and each one names the job it is normally used for. The choice changes how the dry volume is split between cement and sand, and therefore how many bags you buy.

Mix (cement : sand)	Cement share of the dry volume	Sand share of the dry volume	Where the menu places it
1:6	14.3%	85.7%	Interior plaster
1:5	16.7%	83.3%	Brickwork mortar
1:4	20%	80%	Exterior plaster
1:3	25%	75%	Rich mortar mix

The page opens on 1:6, the leanest of the four. Moving to 1:5 on the 10 m² example shows how much one step matters: the cement volume rises from 0.0321 to 0.0374 m³, its weight from 46.2 kg to 53.9 kg, and the bag count from one to two, because 53.9 kg no longer fits in a 50 kg bag. The sand volume falls from 0.192 to 0.187 m³, the mortar cost rises from 12.81 to 20.67, and the wall total from 558.81 to 566.67.

The labels describe typical use, not a specification

The mix menu is a guide to what each proportion is normally used for. The mortar class your project requires — and the cement type, sand grading, and any local or engineer requirement — comes from the specification you are building to, which can call for a different mix at the same proportions.

Getting the number right

Measure the net wall, not the elevation

Openings are not a separate input, so a wall with a window has to be entered with the window already taken out. The 10 m² example with a 1.2 m² window becomes 8.8 m², which returns 381 bricks, or 401 with the same 5% allowance. If the wall is made of several rectangles, add them up first — the square footage calculator handles rectangles and mixed units.

The joint moves the count more than the brick

With a 200 × 100 mm brick, a 10 mm joint gives 43.3 bricks per m². At 8 mm it is 44.5, at 12 mm it is 42.1, and at 15 mm it is 40.4; with no joint at all it reaches 50. A 5 mm change in joint thickness is roughly 7% of the brick order, so measure the joint the bricklayer will actually strike rather than guessing.

Wastage is for broken bricks, not for negotiation

Five percent is a reasonable allowance for new machine-made bricks laid in a straight run. Reclaimed bricks, cut work around openings and corners, and awkward bonds justify ten percent or more, and the field stops at 20%. Cutting is the usual source of loss, which is why a wall with many openings needs the higher figure.

Match the bag and the density to what you can buy

The default bag is 50 kg and the default density is 1440 kg/m³, the dry-cement figure the page starts with. A 25 kg bag, or a 110 lb bag in imperial units, is common elsewhere, and a cement that has settled in the bag can weigh more than its loose volume suggests. Change both fields before you rely on the bag count.

Price the three materials on the same basis

Enter the prices you will really pay for a brick, a bag of cement and a unit of sand. The three currency menus are converted to a common base before the total is added, but keeping them in the same currency makes a merchant quote easier to check. If your sand merchant quotes by weight rather than volume, convert the sand volume to a tonnage with the cubic yards to tons calculator using the sand's density. The total excludes labour, delivery, scaffold and waste removal, so it is a material cost rather than a project cost.

Questions

How many bricks are there in a square metre?

With a 200 × 100 mm brick and a 10 mm joint, one square metre of single-leaf wall takes $1 / 0.0231 = 43.3$ bricks, or about 45.5 with a 5% allowance. A 215 × 65 mm brick with the same joint needs about 59 per square metre before rounding, and a double wall doubles whichever figure applies. The number moves with the joint as much as with the brick, so compute it for the sizes you will actually lay.

How do I allow for a door or a window?

Subtract the opening from the wall area before you start, or enter the net length and height if the wall is a simple rectangle. There is no separate opening field, and nothing is deducted automatically. A 4 m × 2.5 m wall with a 1.2 m² window is entered as 8.8 m², which returns 381 bricks and 401 to order with a 5% allowance.

Does a double wall include the cavity, ties and insulation?

No. Double doubles the bricks and the mortar for two leaves of the size you entered. It does not add wall ties, insulation, a cavity, or any separate skin of blockwork, and it assumes both leaves are built from the brick width in the form. Order those items from their own quantities, and check that the cavity width matches the wall detail you are building.

Limitations

These are material quantities, not a structural design. Load-bearing walls, piers, lintels, movement joints, ties and foundations need an engineer or an experienced mason, together with the building regulations that apply where you are building.
Openings, cutting lists and bond patterns are outside the model. The area you enter must already be net of doors and windows, the wastage allowance is a flat percentage rather than a take-off, and a herringbone or decorative bond is not costed separately.
Mortar proportions are volume ratios, and the mix labels are typical uses. Sand bulking and moisture, cement type, and the mortar class your project specifies all change the real yield, so treat the cement and sand volumes as an estimate and follow the specification for the mix.
Brick dimensions vary between manufacturers and between batches. Measure the bricks you will lay, not the nominal size on the pallet label, and expect the struck joint on site to differ from the 10 mm you entered by a millimetre or two.
Whole bags are rounded up, so the bag count can overshoot. The bag size and cement density are assumptions you can edit; the last bag is bought whole even if only a few kilograms of it are needed.
The cost is a material estimate in the prices you enter. It excludes labour, delivery, scaffold, plant hire, tax and waste removal, and the currency conversion uses a daily exchange rate. Check a large order against a merchant quote before committing to it.

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