Materials for one room, in the order a site buys them

The short answer. A 12 by 10 by 10 foot room needs about 3,710 bricks, 9 bags of cement, two thirds of a brass of sand, 9 boxes of 600 mm tiles and 10 litres of paint, worked out in that order because each answer feeds the next. This guide carries that room through all five calculators, arithmetic shown.

The room: 12 feet by 10 feet, 10 feet high, one door and one window taking about 40 square feet out of the walls, a single-brick external wall, a tiled floor and painted walls. Change the dimensions and every step still applies.

The units, before anything else

Half the errors in a material estimate are conversions, so fix them once.

Material	Measured in	Sold in
Brickwork	square metres of wall	bricks, by the thousand
Sand and aggregate	cubic metres	brass, being 100 cubic feet (2.83 m³)
Cement	cubic metres in the mix	bags of 50 kg
Tiles	square metres of floor	boxes, usually 4 to a box at 600 mm
Paint	square metres of surface	litres, in 20, 10, 4 and 1 litre tins
Steel	metres of bar	kilograms, delivered as counted bars

One cubic metre is 35.31 cubic feet. One brass is 100 cubic feet. Write your room down in one system and convert once, at the end, into whatever the supplier quotes in.

Step 1: the areas, with the openings taken out

Wall area is the perimeter times the height. For this room that is 2 × (12 + 10) × 10 = 440 square feet gross. Take out the door and window, about 40 square feet, and the net wall area is 400 square feet, or 37.2 square metres. The floor is 12 × 10 = 120 square feet, or 11.15 square metres.

Those two numbers drive everything that follows, so measure the room rather than trusting the drawing. A plan says 12 feet; the wall as built is often 11 feet 9.

Step 2: bricks, and the mortar that falls out of them

An Indian modular brick of 190 × 90 × 90 mm laid with a 10 mm joint occupies exactly 200 × 100 × 100 mm, which is one fiftieth of a cubic metre: 500 bricks per cubic metre, 95 per square metre of a single-brick wall. The Brick Calculator does this from your own brick size, joint and wastage.

• 37.2 m² × 95 = 3,530 bricks
• Plus five per cent for breakage and cut bricks at the corners: 3,710 bricks

Now the part that is usually skipped. The mortar is whatever the bricks do not fill, and it is a real quantity: the wall volume is 37.2 × 0.19 = 7.07 m³, the bricks themselves occupy 5.43 m³, so the mortar is 1.63 m³, about 23 per cent of the wall. Multiply by the dry volume factor of 1.33, because you buy sand and cement dry, and you need 2.17 m³ of dry mortar.

Do not use the old "thirty per cent" rule of thumb here. It is high for a modular brick with a thin joint and low for a small brick with a thick one, and the difference is a brass of sand.

Step 3: that mortar, turned into bags and sand

At a 1:6 cement-to-sand mortar, the 2.17 m³ of dry mortar divides into one part cement and six parts sand:

• Cement: 2.17 ÷ 7 = 0.31 m³, times a bulk density of 1440 kg/m³ = 446 kg = 9 bags of 50 kg
• Sand: 2.17 × 6 ÷ 7 = 1.86 m³ = 65.7 cubic feet = about two thirds of a brass

Three conventions are buried in that: 1.33 for dry mortar, 1440 kg per cubic metre for cement, and a 50 kg bag. None is a law, all three are editable on the Cement Calculator, and quoting a bag count without them is how two estimates for the same wall differ by fifteen per cent.

Concrete works the same way with a different factor: 1.54 rather than 1.33, plus aggregate as the third part of the ratio.

Step 4: tiles, where the grout line matters more than you think

Dividing floor area by tile area gives a number that is always slightly too small, because the tile occupies its own size plus the joint. The Tile Calculator counts the joint and the box size for you. A 600 mm tile with a 2 mm grout line takes up 602 × 602 mm, so it covers 0.3624 m², not 0.36.

• 11.15 m² ÷ 0.3624 = 30.8, so 31 tiles bare
• Plus ten per cent for cuts: 34 tiles
• At four tiles to a box: 9 boxes, which is 36 tiles, leaving 2 spare

Ten per cent suits a plain rectangular room laid straight; fifteen or more a diagonal lay or a room full of alcoves, where almost every perimeter tile is cut. Check the carton for tiles per box: 800 mm tiles often come three to a box. Keep the last box rather than returning it; a later batch does not match.

Step 5: paint, from the tin rather than from a rule

The whole answer depends on a number printed on the tin: how many square metres one litre covers in one coat. It is the one input the Paint Calculator cannot guess for you. A smooth interior wall finished with putty takes around 10 m² per litre; rough plaster is closer to 7; a textured exterior can be down at 6.

• Walls only, 37.2 m², two coats at 10 m²/litre = 7.4 litres, or about 7.9 litres with a little wastage for the roller and tray
• Adding the ceiling, 11.15 m², two coats: about 2.3 litres more
• Buy the largest tins first: a 10 litre tin covers the walls, with a 4 litre for the ceiling

Primer is worked out separately: its own coverage, usually one coat, and none on a repaint over sound paint. Bare plaster drinks far more on the first coat than this predicts, and a strong colour change may need a third; both live in the wastage box.

Step 6: steel, which does not come from the room

Rebar quantities come from the bar bending schedule for the slab, beams and columns, not from a floor area, and that schedule comes from the structural drawing. What the Steel Weight Calculator does is convert it: diameter squared over 162 gives kilograms per metre, so a 12 mm bar is 0.888 kg per metre and a standard 12 metre length is 10.65 kg.

The figure to hold on to is bars per tonne, because rebar is sold by weight and delivered by count. At 10.65 kg a bar, a tonne of 12 mm is about 94 bars, so four tonnes should arrive as roughly 376 of them. Count the delivery against that number rather than signing for a weight nobody weighed.

Where the estimate actually slips

Wastage compounds. Five per cent on bricks, ten on tiles, a little on paint, then rounding up to whole bags, boxes and tins. Set the wastage once per material and resist a second margin "to be safe", which is how five per cent quietly becomes twenty.

Rounding to a purchase unit moves the order more than the arithmetic does. Thirty-four tiles becomes nine boxes, which is thirty-six. Round once, at the point of ordering, not at each step.

Plaster is forgotten. Both faces of a brick wall usually get 12 to 20 mm of plaster, and that is another mortar quantity roughly the size of the one in the joints. Run the Cement Calculator in mortar mode for it.

Openings are ignored. A wall with a door and a window in it is not the wall you measured, and the 40 square feet taken out of this room is a tenth of the brickwork.

Counting by volume assumes whole bricks. Round the wall thickness to a whole brick before ordering, and check the result against your mason's own count.

Using this to read a quotation

The reason to do this yourself is not to buy the material. It is to look at a contractor's quotation and see whether the quantities are sensible, which is where the money is. Everybody compares rates; nobody compares quantities, and an honest rate on a generous quantity is the most common way an estimate grows.

Every one of these calculators shows the convention it used and lets you change it, and nothing you type on any of them leaves your browser. They are estimates for ordering and for checking a quotation; structural quantities come from the drawing and from your engineer.

Questions people ask

How many bricks are needed for a 12 by 10 room?

About 3,710 for a single-brick wall 10 feet high with one door and one window: 400 square feet of net wall is 37.2 m², and at 95 modular bricks per m² that is 3,530, plus five per cent for breakage and cut bricks at the corners. A double-brick wall doubles it.

How many cement bags are needed for brickwork?

For this room's 1.63 m³ of mortar, which is 2.17 m³ dry, a 1:6 mix needs 0.31 m³ of cement: 446 kg, or 9 bags of 50 kg, with 1.86 m³ of sand, about two thirds of a brass. Plaster on both faces of the wall needs roughly the same quantity again.

How many tiles for 120 square feet?

34 tiles of 600 mm, bought as 9 boxes of four. The floor is 11.15 m², and a 600 mm tile with a 2 mm joint covers 0.3624 m², so 31 tiles bare plus ten per cent for cuts. Allow fifteen per cent for a diagonal lay, and read the tiles-per-box figure off the carton.

Sources

Checked 22 Oct 2026:

• Bureau of Indian Standards, bis.gov.in: IS 1077 (common burnt clay building bricks, the 190 × 90 × 90 mm modular size), IS 2250 (preparation and use of masonry mortars) and IS 1786 (high strength deformed steel bars; the d² ÷ 162 rule follows from their 7,850 kg/m³ density)
• Conversions used: 1 m³ = 35.31 cubic feet; 1 brass = 100 cubic feet (2.83 m³)
• Every quantity on this page is this guide's own arithmetic on the room at the top, rounded as a supplier sells it