Calculators

Tile and flooring quantity calculator

The area is the easy part. The waste allowance is where a flooring order goes wrong.

By the Refined Space editorial desk · Updated September 6, 2026 · How we work

On this page (7 sections)

Tile and flooring quantity calculator
The four inputs: room, unit, layout, pack
Why 10 per cent becomes 22 per cent in herringbone
120 sq ft in 12 x 24 in tile, worked by hand
The grid, the last cut and where to start
Unit areas from 12 x 12 in to 8 x 48 in
Where the count stops: adhesive, borders, stairs

Short answer

A 10 x 12 ft room is 120 sq ft (11.1 m2), which is exactly 60 tiles at 12 x 24 in (300 x 600 mm) and 66 ordered once the 10 per cent allowance for a straight lay is added. Turn the same floor to herringbone and the allowance rises to 22 per cent, or 74 tiles. Order too few and the second delivery is a different batch. Order too many and you have paid for a pallet you will store for a decade.

The numbers, at a glance

Straight or stack bond waste: 10 per centTrade practice for a plain rectangle
Brick or third offset waste: 12 per centOne extra cut at each end of a row
Diagonal, 45 degrees: 17 per centEvery perimeter unit becomes a triangle
Herringbone or chevron: 22 per centMost perimeter units take two cuts
Worked example room: 120 sq ft (11.1 m2)10 x 12 ft (3.0 x 3.7 m)
Tiles ordered, straight lay: 66 at 12 x 24 in (300 x 600 mm)60 net, plus 10 per cent, rounded up
Grout joint in that room: 180 linear ft (55 m)Counted per unit, so slightly generous
Smallest perimeter cut worth having: One third of a unit width4 in (10 cm) on a 12 in tile
Spare to keep after the job: One full packBatch colour drifts between runs

Tile and flooring quantity calculator#

Enter the room and the material. The calculator returns the area, the waste allowance appropriate to the layout, the number of tiles or packs, and the grout line count.

Room width in

Room length in

Tile or plank width in

Tile or plank length in

Layout

Units per pack (0 if sold singly)

Enter your measurements above.

Waste allowances follow trade practice: 10 per cent for a straight lay in a simple rectangle, more for diagonal and herringbone, and more again for a room with several cut edges.

Nothing you type leaves your browser: the maths runs on this page, and no values are stored or sent anywhere.

The four inputs: room, unit, layout, pack#

Four numbers go in: the room, the unit, the layout and the pack size. Everything the panel reports is derived from those four by multiplication, division and one rounding up, and all of it happens in your browser. Nothing you type is sent anywhere.

The room width and length are the finished dimensions at floor level, wall face to wall face, taken before skirting is fitted, because tile is laid to the wall and skirting sits on top of it. Take both dimensions twice at opposite ends of the room, use the larger of each pair, and record the diagonals, using the method in how to measure a room properly. A room 1 in out of square generates a tapered cut down one wall that the calculator cannot see.

The unit width and length are nominal catalogue sizes. The calculator treats a 12 in tile as covering 12 in of floor, which ignores the joint: at 3 mm the true module is closer to 12.12 in (308 mm). That overstates the count very slightly, which is the direction to be wrong in. Joint widths by tile type are in grout line widths and joint sizing.

Why 10 per cent becomes 22 per cent in herringbone#

The allowance is not a property of the material. It is a property of the layout, because every unit that meets a wall gets cut and roughly half of each cut unit becomes offcut.

Layout	Allowance the calculator adds	Why
Straight or stack bond	10 per cent	One cut per unit at each perimeter
Brick or third offset	12 per cent	Alternate rows start and end with a part unit
Diagonal, 45 degrees	17 per cent	Every perimeter unit is cut to a triangle
Herringbone or chevron	22 per cent	Most perimeter units take two cuts, and chevron cuts are handed

These are trade allowances, not code and not a published standard. They match what tilers quote and sit at the conservative end for a plain rectangle. The setting out behind the herringbone figure is covered in herringbone and chevron layout dimensions.

120 sq ft in 12 x 24 in tile, worked by hand#

Take a room 120 x 144 in (10 x 12 ft, 3.0 x 3.7 m) and a 12 x 24 in (300 x 600 mm) porcelain tile, laid straight.

Area: 120 x 144 = 17,280 sq in, which is 120 sq ft (11.1 m2).
Unit area: 12 x 24 = 288 sq in, or 2 sq ft.
Net units: 17,280 divided by 288 = 60 tiles exactly.
Waste: 60 x 1.10 = 66 tiles.
Packs of eight: 66 divided by 8 is 8.25, so nine packs, 72 tiles, with 12 spare over the 60 the floor consumes.

The same floor in herringbone is 60 x 1.22 = 73.2, rounded up to 74 tiles: eight more tiles for the same room, decided entirely by the angle they are laid at. Conversions between the box coverage printed on a pack and the area of your room are tabulated in tile and flooring quantity conversions, and the square metre equivalents of common room sizes in square feet to square metres for rooms.

The grid, the last cut and where to start#

The calculator also divides the room into a grid: 120 divided by 12 is 10 columns, 144 divided by 24 is six rows. The last column cut is the room width minus nine full tiles, which here is a full 12 in, so the floor happens to tile out exactly.

Move the wall 2 in and it stops being tidy. A 122 in (310 cm) wide room gives 11 columns and a 2 in (5 cm) strip on the last one. The calculator flags any final cut under about a third of a unit width, because a sliver that narrow snaps on the saw, wanders off the line and reads as a mistake from the doorway. The fix is to shift the whole setting out by half a tile so both walls get a 7 in (18 cm) cut instead of one wall getting 12 in and the other 2 in.

Two limits are worth knowing. The calculator checks the cut across the width only, so swap the dimensions and run it again if the length is the critical direction. And its grid starts from a corner, which is almost never where a tiler starts: setting out normally begins on a centre line or the most visible edge, as described in tile sizes and layout dimensions.

The waste allowance is a perimeter figure wearing an area costume

A percentage of area is the wrong shape of rule, because cuts do not happen in the middle of a floor. They happen at the edge, and the amount of material that goes through the saw is the perimeter multiplied by roughly half a unit, of which about half comes back as a usable offcut at the opposite wall.

Run that on the example room. The perimeter is 44 linear ft, half a 12 in tile is 0.5 ft, and half the resulting band is unusable: 44 x 0.5 divided by 2 is 11 sq ft, or 9.2 per cent of 120 sq ft. The familiar 10 per cent is not a general truth: it is what the perimeter rule produces for a medium room in a medium unit.

Change either variable and it collapses. A 5 x 7 ft shower room is 35 sq ft with a 24 ft perimeter, and in 24 x 24 in (600 x 600 mm) tile the cut band is 12 sq ft, or 34 per cent, where the standard allowance would have ordered 3.5 sq ft. Our working rule, and it is ours rather than a published one: estimate waste as the perimeter multiplied by the unit's short side, divided by four, then use the higher of that and the layout percentage. Big tiles in small rooms are where flooring orders fail, and the percentage never sees it coming.

Unit areas from 12 x 12 in to 8 x 48 in#

Pack quantities vary by maker, but unit areas do not, and dividing your room area by the area of one unit catches an ordering error before it becomes a delivery.

Nominal unit	Metric	Area each	Units per 100 sq ft (9.3 m2)
12 x 12 in tile	300 x 300 mm	1.00 sq ft	100
12 x 24 in tile	300 x 600 mm	2.00 sq ft	50
24 x 24 in tile	600 x 600 mm	4.00 sq ft	25
6 x 36 in plank	150 x 900 mm	1.50 sq ft	67
8 x 48 in plank	200 x 1,200 mm	2.67 sq ft	38
5 x 48 in board	127 x 1,220 mm	1.67 sq ft	60

Plank floors carry a constraint the calculator does not model: the length distribution in the box, and the stagger required between end joints in adjacent rows. Both are in floor plank widths, lengths and proportions.

Where the count stops: adhesive, borders, stairs#

It is a planning tool, not a take-off, and it sizes an order to about the nearest pack.

It takes one rectangle. Split an L-shaped room into two and add the answers, without assuming offcuts travel between them.
It ignores the grout joint and the perimeter expansion gap. The count still holds, since the gap comes out of full units, but the gap sizes are in expansion gaps and perimeter details.
It does not estimate adhesive, grout weight, levelling compound or underlay. Build-ups are in underlay and subfloor thickness.
It does not count stair treads and risers, which are separate: see stair tread and riser flooring dimensions.

For the rest of the set, including the room and lighting tools that run on the same rectangle you just measured, see the calculators index.

Frequently asked questions#

How much extra tile should I order?

Ten per cent over the measured area for a straight lay in a simple rectangle, 12 per cent for a brick or third offset, 17 per cent for a 45 degree diagonal and 22 per cent for herringbone or chevron. Those are trade allowances rather than a published standard. Small rooms and large tiles need more, because waste is generated at the perimeter and a small room is almost all perimeter.

Does the calculator account for the grout joints?

No. It uses the nominal unit size, so a 12 in tile is treated as covering 12 in of floor when a 3 mm joint actually makes the module 12.12 in. The effect is small and it errs the safe way: ignoring the joint slightly overstates how many units you need. On a big floor with wide joints, expect to have one or two spare units beyond the waste allowance.

How do I work out tiles for an L-shaped room?

Split the plan into rectangles, run the calculator once for each, and add the results without reusing offcuts between them. The calculator takes one rectangle and assumes cuts from one edge can be used at the opposite edge, which only holds within a single continuous run. Two runs meeting at a corner each generate their own perimeter waste, so adding the two answers is the honest total.

Why does the calculator warn about the last column?

Because a sliver at the wall is the most common setting-out mistake. It divides the room width by the unit width and reports the cut left on the final column. If that cut is under about a third of a unit it flags it, since a 2 in (5 cm) strip is fragile, hard to lay straight and visually obvious. Shifting the whole grid by half a unit splits the same waste between both walls.

How many packs of tile do I need?

Enter the units per pack and the calculator divides the total by it and rounds up, then reports the spare units left over. Packs are the real ordering unit and they force the number up: 66 tiles in packs of eight is nine packs, which is 72 tiles and 12 spare against the 60 that cover the floor. Keep one full pack rather than loose tiles.

Is the grout quantity in linear feet useful?

It tells you how much joint there is to fill, not how many kilograms of grout to buy. The calculator counts each unit's own width and length, which includes the perimeter and double counts shared joints slightly, so the figure runs about 10 to 15 per cent above the true joint length. Convert it to weight using the coverage table on the grout bag, which depends on joint width and depth.

Sources and standards referenced#

TCNA Handbook for Ceramic, Glass and Stone Tile Installation Tile Council of North AmericaSetting out, movement joints and layout practice for floor tiling
BS 5385: Wall and floor tiling British Standards InstitutionJoint widths, setting out and substrate requirements
Installation Guidelines National Wood Flooring AssociationExpansion allowance and plank layout practice used for board floors
Architects' Data Ernst Neufert, Wiley-BlackwellStandard tile modules and floor finish build-ups
Time-Saver Standards for Interior Design and Space Planning De Chiara, Panero and Zelnik, McGraw-HillFloor finish dimensions and quantity estimating method

We cite published codes, industry planning guidelines and manufacturer specifications. Where a figure is our own recommendation rather than a published standard, the text says so. See how we measure.