Tile Calculator
Most tile calculators hand you a number. This one hands you a purchase plan: how many boxes to put in the cart, how much thinset and grout to grab on the same aisle, and what the whole trip should cost.
Reviewed · Method: measured area + industry waste allowance, rounded up to real package sizes · How the numbers are calculated
Enter your dimensions and hit Calculate my tile order. You will get the quantity, the buyable quantity, a shopping list, and a budget range.
Figure. How 120 sq ft of floor becomes 9 cartons: the waste allowance and the carton size both matter more than the raw area.
Figure. Measure the room at its widest points. The cut strip along the wall is what the waste allowance is for.
How this tile calculator works
It multiplies room length by width to get the area, adds your waste allowance, then divides by the carton coverage to get boxes. That last step is the one most calculators skip. Tile is sold by the box, not by the square foot, so a room that needs 118 sq ft of tile at 15.5 sq ft per box requires 8 boxes (124 sq ft), not 7.6. The difference is not rounding pedantry — it is the reason people make a second trip to the store mid-install.
Why 10% waste is the right default
Waste is not a fudge factor, it is the physical reality of cutting. A simple rectangular room tiled straight-lay with large format tile wastes 5-7%. Add a doorway, a vanity cutout, or a diagonal layout and you are at 10-15%. Small formats like 3-inch hexagons with mosaic borders can waste 20% because offcuts cannot be reused.
Keep one full box unopened after the job. Dye lots change between production runs, and a cracked tile two years from now will not match anything you can buy off the shelf.
The sundries that blow the budget
Tile is roughly 60-70% of the material cost. The line items people forget: thinset (about one 50 lb bag per 50 sq ft), grout (one 10 lb bag per 250 sq ft for 12x24 with a 1/8-inch joint), spacers, a mixing paddle, sponge and bucket, and waterproofing membrane if the area is wet. This calculator lists all of them with quantities.
Reading the budget range
Low is ceramic or clearance porcelain. Mid is standard porcelain in a current colorway. High is large-format, rectified edge, or natural stone. These bands cover materials only — no labor, no delivery, no old-floor removal. Regional pricing swings these numbers by 30-40%, so treat the range as a planning envelope, not a quote.
How to measure a room that is not a rectangle
Split the floor into rectangles, measure each one, add the results. An L-shaped room is two rectangles; a room with a closet is three. Do not measure the wall length and assume the floor is the same size, because baseboard thickness and door casings eat an inch or two on every wall.
For a diagonal or herringbone layout, measure the same way but raise the waste allowance to 15%. The pattern does not change the area, it changes how much of each tile is unusable after cutting.
Backsplashes and walls work differently
Wall area is height times width, then subtract the range, the hood and any full-height cabinet. A typical kitchen backsplash is 18 in tall, not 24, and that difference alone is a full carton on a large kitchen.
Wall tile needs more waste than floor tile, not less. Outlets, switches and window returns all create cuts that cannot be reused, and a 15% allowance is the honest default. Use a modified thinset on walls, because gravity is working against you the whole time.
Where the budget band comes from
The low band is ceramic or clearance porcelain. The mid band is current-colour porcelain in a standard size. The high band is large-format, rectified-edge or natural stone, which also needs a more expensive mortar and a levelling clip system.
None of the three bands include labour, delivery, old-floor removal or waterproofing membrane. Regional pricing moves these numbers by 30 to 40% in either direction, so treat the band as a planning envelope rather than a quote you can hold a supplier to.
Worked example: 12 x 10 ft floor, 12x24 in tile
| Floor area | 12 x 10 = 120 sq ft |
| With 10% waste | 120 x 1.10 = 132 sq ft |
| Cartons needed | 132 / 15.5 = 8.5, rounded up to 9 |
| Tile actually delivered | 9 x 15.5 = 139.5 sq ft |
| Pieces | About 70 tiles at 2 sq ft each |
| Thinset | 3 bags of 50 lb |
| Grout | 1 bag of 10 lb |
| Budget band | $451 low, $822 mid, $1,553 high |
Mistakes that cost real money
Ordering by tile count instead of carton coverage
Tile is sold by the carton, and the coverage printed on the carton is the only number that matters. Two 12x24 cartons from different makers can differ by a square foot. Counting pieces and dividing by 2 gets you a number you cannot buy.
Treating 10% waste as generous
On a straight-lay rectangle the true loss is 5 to 7%. Add one doorway, one vanity cutout and a diagonal layout and you are past 10%. On small formats with mosaic borders, 20% is normal because offcuts cannot be reused.
Ignoring the dye lot
Tile is fired in batches and colour shifts between runs. A box bought two years later will not match, no matter how standard the colour name sounds. Keep one full carton sealed and store it flat and dry.
Buying thinset by area instead of by trowel
Coverage depends on the notch size, not the floor. A 3/8 in notch covers far less than a 1/4 in notch. Large-format tile also needs back-buttering, which adds 15 to 20% more mortar than the bag chart suggests.
Skipping the substrate check
The calculator knows your floor area, not whether the substrate is flat. A 1/4 in dip over 10 ft doubles the mortar bed in that zone and can void a large-format warranty. Check flatness with an 8 ft straightedge before ordering.
Frequently asked questions
How many tiles are in a box?
It varies by manufacturer. A 12x24 porcelain carton typically covers 15.5 to 16 sq ft, which is about 8 tiles. A 12x12 carton usually covers 10 to 15 sq ft. Always read the coverage printed on the carton rather than counting pieces.
Should I order 10% extra tile?
Yes for most installations. Ten percent covers cutting waste, breakage in transit, and future repairs. Go to 15% for diagonal or herringbone patterns, and 20% for small formats where offcuts cannot be reused.
Do I need to buy thinset and grout separately?
Almost always. Thinset and grout are rarely included with tile. Budget roughly one 50 lb bag of thinset per 50 sq ft and one 10 lb bag of grout per 250 sq ft of 12x24 tile with a standard joint width.
How much does tile installation cost per square foot?
Material alone runs about $2 to $9 per sq ft depending on grade. Professional installation typically adds $5 to $15 per sq ft, which is why this tool does not quote labor — it varies too much by region and site conditions.
Can I use this for a wall or backsplash?
Yes. Measure the wall height times width. For backsplashes, subtract the range and hood area. Wall tile with many outlet cuts should use a 15% waste allowance.