Flooring & Tile Calculator
Boxes of tile, plank, or laminate for the whole job — rooms added up, islands and hearths taken out, waste set by how you're laying it.
One row per rectangle. Add a row for each room, hall, or alcove, and tick "leave out" for anything the floor doesn't cover.
Rooms in ft, tiles in in.
Cartons print a coverage figure, but you probably know the tile size instead. Either works.
One box covers 16 sq ft.
How you lay it decides this, not how big the room is. Pick a pattern to set a starting figure, then adjust.
Add 5 more for a small or awkward room — offcuts stop being reusable.
Yours to supply — we don't ship prices that go stale.
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9 boxes
144 sq ft of material for 120 sq ft of floor
Flooring is sold by the box and laid by the square foot, and the gap between those two units is where orders go wrong. A 12 × 10 room is 120 square feet — that part is easy. But tile comes 16 square feet to a carton, you will cut into more of it than you lay, and the shop will not sell you three-quarters of a box. The honest answer for that room is nine boxes: 144 square feet bought to put 120 square feet down, with 24 square feet left over.
The same job in metric behaves identically, because the arithmetic does not care: a 3.6 × 3 m room is 10.8 m², a box of eight 300 × 600 mm tiles covers 1.44 m², and a 10% allowance takes 10.8 to 11.88 — nine boxes again, 12.96 m² bought with 2.16 m² spare. Switch the toggle at the top and every field, label, and figure follows.
That leftover is not a mistake in the estimate. It is the estimate working.
The waste allowance is about how you lay it, not how big the room is
This is the number most calculators get wrong by treating it as a flat 10%, and it is the single biggest lever on what you actually buy. The reason is geometric. Lay a floor straight, parallel to the walls, and the piece you cut off the end of one row is a rectangle — the right shape to start the next row. Very little is genuinely lost, so 10% covers the ends, the breakages, and the two pieces you will ruin learning the saw.
Turn the same floor 45° diagonal and every wall becomes a run of angled cuts. Each one leaves a triangle, and a triangle only fits the opposite corner of the room — where, if you are lucky, you happen to need exactly that triangle. Usually you are not. That is why a diagonal lay wants 15%.
Herringbone and chevron are worse again, at 20%, because the pattern dictates which end of each piece is cut and at what angle. You cannot save an offcut for later if the pattern needs its mirror image and you are holding its twin. Cut the wrong hand and the piece is scrap.
Then add about 5% more for a small or awkward room, and this is the part that catches people out. In a big open floor an offcut has somewhere to go: there is always another row to start, another corner to fill. In a small bathroom with a doorway, a vanity, and a toilet flange, the cuts come thick and fast and the offcuts have nowhere to be used. The percentage is the same arithmetic but the reality is worse, so the allowance has to be higher in the room where the total is smallest — which feels backwards and is not.
Worth knowing: the round-up sometimes swallows the whole difference. That 12 × 10 room needs nine boxes at 10%, nine at 15%, and still nine at 20% — 132, 138, and 144 square feet all land inside the same nine cartons. Change nothing but the room size and it separates: a 20 × 15 floor, 300 square feet, takes 21 boxes laid straight and 23 in herringbone. Two extra boxes is real money, and it is invisible until you calculate it.
Metric shows the same two behaviours at the same scale, which is a useful sanity check rather than a coincidence. A 3.6 × 3 m room takes nine boxes of 1.44 m² tile at every pattern from 10% to 20%; a 6 × 4.5 m room — 27 m² — takes 21 straight and 23 in herringbone. The threshold is not about the unit, it is about whether the extra allowance clears a whole box.
Add the rooms up, and take the island out
Almost no real floor is one rectangle. A living room opens into a dining area, a hall connects them, and the kitchen has an island sitting in the middle of it that needs no floor underneath. So this calculator takes a list: one row per rectangle, each one either adding floor or being left out.
Break an L-shaped space into two rectangles at the corner rather than trying to average it. Measure the widest point of each, because that is what you have to cut to. For anything with a curve or an angled wall, take the bounding rectangle — you will cut the shape out of material you had to buy anyway, and the offcut is scrap either way.
Things worth leaving out: a kitchen island or peninsula, a fireplace hearth, a full-height built-in cabinet run, a stair opening, a floor-mounted radiator. Things not worth leaving out: doorways, because you floor through them and thresholds need material, and anything under a kick space, dishwasher, or fridge — appliances get replaced, and a floor that stops at the old one is a problem later. Under fitted base cabinets is a genuine judgement call; the cautious answer is to floor it, and the cheap answer is not to.
The breakdown lists every row signed, and the rows add up to the total on screen. If you deduct more than you measured, the deduction is capped rather than the total going negative, so the rows always reconcile with the figure they are supposed to explain.
Getting the coverage per box right
Cartons print a coverage figure and it is the number to trust. Type it in and be done. But most people do not have the carton in front of them when they are estimating — what they know is the size on the sample: 12 × 24 inch tile, 8 to a box. So the other mode does that division for you. A 12 × 24 tile is 288 square inches, which is 2 square feet, and eight of them is 16 square feet a box. A 12 × 12 tile twelve to a box is 12 square feet. A 6 × 36 inch plank eight to a box is also 12 — the same coverage from a very different-looking product.
In metric the same two routes apply, with millimetres instead of inches: a 300 × 600 mm tile is 180,000 mm², which is 0.18 m², and eight of those is 1.44 m² a box. A 600 × 600 mm tile four to a box is the same 1.44. If you think in centimetres, that tile is 30 × 60 cm — the calculator wants it in millimetres, because that is the number printed on the box.
Get the divisor right and nothing else matters: 144 from square inches to square feet, 1,000,000 from square millimetres to square metres. Dividing by 12 or by 1,000 instead is the classic slip, and it is off by the same factor again — obvious once you look at the answer, invisible if you do not.
Here is the thing worth knowing, and it explains why imperial carton figures look so odd. A "12 × 24 inch" tile is not 12 × 24 inches. It is 300 × 600 mm, which is 11.81 × 23.62 inches, because essentially all tile in the world is made to metric sizes and the inch figure is a nickname. So a box of eight covers 15.5 sq ft, not the 16 the nominal size implies — and that is exactly the number the carton prints. The same box in metric prints a clean 1.44 m². If the "one box covers" line here disagrees with the carton by about 3%, this is why, and the carton wins: enter its figure directly rather than the nominal tile size.
Why the box count rounds the way it does
Boxes always round up, and the calculator shows the fractional figure next to the whole one so you can see how close the call was. 8.25 boxes is 9. So is 8.9. If you land on 8.05 it is worth a moment's thought: shaving a point off the waste allowance or measuring the room again more carefully might genuinely save a box, whereas at 8.9 nothing short of a different tile will.
An exact fit stays exact. 160 square feet of straight-laid floor at 16 square feet a box is ten boxes, not eleven — floating-point arithmetic makes that division come out a hair over ten in binary, and buying an eleventh box for a rounding error in a computer is not a tradition worth keeping. The metric side needs this more, not less: 14.4 m² at 1.44 m² a box is ten boxes, and almost none of those decimals are exactly representable in binary.
Two things the box count deliberately does not do. It does not pool the spare across rooms you are covering in different materials — run those as separate calculations. And it does not assume you will use the offcuts from one room in the next, because whether you can depends on the pattern and on whether the batches match, which no calculator can know.
Order it all at once, and keep the spare
Buy the whole job in one order from one place. Tile and wood are made in batches — dye lots for tile, cut and stain runs for wood — and two batches of nominally identical material can differ enough to see under a window. If you come up two boxes short a month later you may not be able to get the same material at all, and a patch that nearly matches reads worse than one that obviously does not.
Keep the leftovers rather than returning them. A box in the garage is the repair for the tile that cracks when something heavy lands on it, or the plank that swells after a leak. That is also why the spare is shown in square feet rather than as a percentage: a repair needs pieces, and knowing you have most of a box left is more useful than knowing you overbought by twenty percent.
Cost, and why there are no prices here
Give it a price per box and it will total the boxes for you — which is the boxes you buy, not the area you lay, because you pay for the ninth box whether or not you open it. That is the number to compare against another material's, and it is why the comparison often surprises: a cheaper tile in a bigger box can lose to a dearer one that rounds better, and per-square-foot pricing hides that completely.
There are no built-in prices, on purpose. Flooring pricing varies by region, by store, and by month, and a figure baked into a calculator would be quietly wrong within a season. A stale price presented confidently is worse than no price at all. What this does not cover is underlayment, adhesive, grout, trim, transition strips, and tools — on a tile job those can add half again to the material cost, so treat the total here as the flooring line of the budget and not the budget.
Measuring well beats estimating well
The largest error in any flooring estimate is usually the tape measure, not the arithmetic. Measure each room at its widest, in two places, and take the larger — walls are not parallel and rooms are not square, and being half an inch out over sixteen feet is most of a box. Round every measurement up to the next inch. If the floor is going in before a wall comes out or a cabinet goes in, measure the room you will have, not the one you are standing in.
And measure in feet with inches as a fraction if that is what your tape says — "12 1/2" is read here just as happily as "12.5", so there is no conversion step in which to lose a number.
If you measured in one system and are buying in the other, switch the toggle rather than converting by hand: your room dimensions come across with you (12 ft becomes 3.66 m), while the tile size resets to a sensible metric starting point. That split is deliberate. A room is a measurement and deserves to survive; a tile is a product, and converting a 12 × 24 inch tile would give 304.8 × 609.6 mm — a spec nobody sells. Type your actual tile instead. Converted dimensions are rounded to the nearest centimetre, so a round trip through both systems can shift a figure by about a centimetre. That is well under what a tape measure resolves, and far less than the error from measuring a room that is not quite square.
How many boxes of tile do I need for a 12x10 room?
Nine, for a typical 12 × 24 inch tile that comes 16 square feet to a box, laid straight with a 10% waste allowance. The room is 120 square feet, the allowance takes it to 132, and 132 ÷ 16 is 8.25 boxes — which rounds up to 9. You will bring home 144 square feet of tile to put 120 square feet down and have 24 square feet left over, and that is the estimate working correctly rather than an error in it. The metric equivalent lands in the same place: a 3.6 × 3 m room is 10.8 m², a box of eight 300 × 600 mm tiles covers 1.44 m², and 11.88 ÷ 1.44 is again 8.25 boxes, so again nine.
How much extra flooring should I buy for waste?
It depends on how you lay it, not on how big the room is. A straight or grid lay wants about 10%, because the offcut ending one row starts the next. A 45° diagonal wants 15%, because every wall becomes a run of angled cuts and each one leaves a triangle. Herringbone and chevron want 20%, since the pattern dictates which end of each piece is cut and an offcut of the wrong hand is scrap. Add roughly 5% on top for a small or awkward room — the cuts come more often and the offcuts have nowhere to be reused.
How do I work out the square feet in a box of tile?
Multiply the tile's length by its width in inches, divide by 144 to get square feet per tile, then multiply by the number of pieces in the box. A 12 × 24 inch tile is 288 square inches, so 2 square feet each; eight of those is 16 square feet a box. A 12 × 12 tile twelve to a box is 12 square feet, and so is a 6 × 36 inch plank eight to a box — the same coverage from products that look nothing alike. Divide by 144 rather than 12; that slip is the common one and it is off by a factor of twelve.
How do I calculate square metres of tile per box?
Multiply the tile length by the width in millimetres, divide by 1,000,000 to get square metres per tile, then multiply by the pieces in the box. A 300 × 600 mm tile is 180,000 mm², so 0.18 m² each, and eight of those is 1.44 m² a box — as is a 600 × 600 mm tile four to a box. Divide by a million, not a thousand: that is the metric version of the ÷144 slip and it is off by the same factor of a thousand. If you are working in centimetres, convert to millimetres first (30 × 60 cm is 300 × 600 mm), because millimetres are what the carton quotes.
Should I subtract doorways, cabinets, or kitchen islands?
Islands, hearths, full-height built-in cabinet runs, stair openings, and floor-mounted radiators are worth leaving out — nothing goes underneath them. Doorways are not: you floor through them and thresholds need material. Neither is the space under a dishwasher, fridge, or kick space, because appliances get replaced and a floor that stops at the old one becomes a problem. Under fitted base cabinets is a real judgement call — flooring it costs material now and saves grief if the kitchen ever changes.
Does a diagonal or herringbone floor really need more tile?
Yes, though the round-up sometimes hides it. A 12 × 10 room takes nine boxes at 10%, 15%, or 20% — 132, 138, and 144 square feet all fit inside the same nine cartons. But a 20 × 15 floor of 300 square feet takes 21 boxes laid straight and 23 in herringbone, because at that size the extra 10% clears two whole box boundaries. Metric behaves the same way at the same scale: a 3.6 × 3 m room is nine boxes at every pattern, while a 6 × 4.5 m room of 27 m² goes from 21 boxes to 23. The bigger the floor, the more the pattern costs you, and the difference is invisible until you calculate it.
Can I use this for laminate, vinyl plank, or hardwood?
Yes — the arithmetic is area divided by coverage per box, and it knows nothing about the material. Plank flooring is sold the same way tile is, by the carton with a published square-footage coverage, so both modes work: type the carton figure, or give the plank size and the pieces per box. The waste guidance transfers too, with one addition — for long plank you also have to stagger the end joints, which consumes offcuts you might otherwise reuse, so sit at the top of the range rather than the bottom.
Why does it round up to a whole box?
Because shops sell whole boxes. The tool shows the fractional figure beside the whole one so you can see how close the call was, which matters: at 8.05 boxes it is worth remeasuring or shaving a point off the waste allowance to save a box, while at 8.9 nothing short of a different tile will help. An exact division stays exact — 160 square feet at 16 square feet a box is ten boxes, not eleven, because a floating-point rounding error should not cost you a carton.
Should I order all the flooring at once?
Yes. Tile is made in dye lots and wood in cut and stain runs, and two batches of nominally identical material can differ enough to notice under a window. If you run short a month later the same batch may be gone, and a patch that nearly matches looks worse than one that obviously does not. It is also why the leftovers are worth keeping rather than returning — a spare box in the garage is the repair for the tile that cracks in three years.
Can I use this in metric — square metres and millimetres?
Yes. The toggle at the top of the Areas card switches every input, label, and result between imperial (feet, inches, square feet) and metric (metres, millimetres, square metres). Switching converts your room dimensions with you, since a room is a physical measurement — 12 ft becomes 3.66 m — but resets the tile size and carton coverage to sensible metric starting points, because a tile is a product rather than a measurement and converting a 12 × 24 inch tile would suggest a 304.8 × 609.6 mm one that nobody sells. Converted dimensions round to the nearest centimetre, so a round trip through both systems can move a figure by about a centimetre, which is well below what a tape measure resolves.
Why does the carton say 15.5 sq ft when the tile is 12 x 24 inches?
Because it is not really a 12 × 24 inch tile. It is a 300 × 600 mm tile — 11.81 × 23.62 inches — and the imperial name is a nickname. Almost all tile in the world is manufactured to metric sizes, so nominal inch dimensions are rounded-off labels and the carton coverage is computed from the real ones: eight of them cover 15.5 square feet, not the 16 the nickname implies. The same box in metric prints a clean 1.44 m². If the tile-size mode here disagrees with your carton by roughly 3%, this is why — enter the carton figure instead, because the carton is measuring the tile you are actually buying.
Why does the calculator not include flooring prices?
Because flooring prices vary by region, by store, and by month, and a figure baked in here would be quietly wrong within a season — a stale price presented confidently is worse than no price. Supply your own price per box and it will total the boxes you buy, which is the right basis for comparison: a cheaper tile in a bigger box can lose to a dearer one that rounds better, and per-square-foot pricing hides that. Bear in mind the total covers flooring only, not underlayment, adhesive, grout, trim, or tools.