Tile Calculator

How much tile do I need?

Tile is sold by the piece or the carton, but floors, walls, and showers are measured in feet. To get from one to the other, multiply the area's length by its width, add an allowance for cuts and breakage, and divide by the face area of one tile. The calculator then divides the same area by the coverage printed on the box to tell you how many cartons to carry out of the store, and by your thinset bag's coverage to count mortar.

For anything other than a plain rectangle, split the space into rectangles and add them, or measure it first with the square footage calculator for L-shaped and multi-part rooms and enter the total as a length with a width of 1. Walls work the same way: width times the height you plan to tile, minus large openings such as windows and doors.

Worked example: a 10 × 10 ft floor in 12 × 24 tile

Say you're tiling a 10 × 10 ft bathroom floor with 12 × 24 in porcelain, the carton is labelled 16 sq ft (eight tiles), and you're spreading thinset with a 1/4″ × 3/8″ square-notch trowel.

1. Floor area: 10 ft × 10 ft = 100 sq ft.
2. With a 10% cut allowance: 100 × 1.10 = 110 sq ft.
3. One tile: 12 in × 24 in = 288 sq in ÷ 144 = 2 sq ft, so 110 ÷ 2 = 55 tiles.
4. Cartons: 110 ÷ 16 = 6.9, which rounds up to 7 boxes (56 tiles).
5. Thinset at about 63 sq ft per 50 lb bag: 110 ÷ 63 = 1.75, so 2 bags.
6. Spacers at four per tile: 55 × 4 = 220 as an upper bound.

The same floor in 12 × 12 tile needs 110 tiles. In metric, a 3 × 3 m room is 9 m², or 9.9 m² with 10% extra; 30 × 60 cm tiles cover 0.18 m² each, so you'd need 55 of them.

Tiles per square foot by tile size

An a × b inch tile covers a × b ÷ 144 sq ft, so the number of tiles per square foot is 144 ÷ (a × b). Nominal sizes are used below; real tiles are often a few millimetres smaller to leave room for the grout joint, which changes the count very little.

Per-100 counts are rounded up to whole tiles. Cartons hold different numbers of tiles from brand to brand, so use the coverage printed on the box rather than assuming a tiles-per-box figure.

Formula & methodology

Area = length × width, plus a waste allowance (default 10%) for offcuts, breakage, and the odd mis-cut. Tiles = area with waste ÷ area of one tile, rounded up. Boxes = the same area ÷ the coverage per box, rounded up because stores don't sell cartons by the fraction. Mortar bags = area with waste ÷ coverage per bag, also rounded up.

A 10% allowance suits a straight grid in a simple room. Raise it to 15–20% for diagonal or herringbone layouts, small rooms where most tiles are cut, and showers with niches and fixtures to cut around. Large-format tile wastes more per bad cut, since each piece is a bigger share of a box.

US mode takes the room in feet, the tile in inches, and coverage in square feet; the mortar defaults assume 50 lb bags. Metric mode takes metres, centimetres, and m², and switching converts the numbers already in the form. Thinset outside the US is usually sold in 20 or 25 kg bags; the 8.4 and 5.9 m² presets are for a 50 lb (≈ 22.7 kg) bag, so read the coverage off your own bag and type it in.

Mortar & spacers

How far a bag of thinset goes depends mostly on the trowel notch: a deeper notch leaves a thicker bed and covers less floor per bag. The presets come from the coverage chart Custom Building Products publishes for its CustomBlend thinset mortar, rounded to the middle of each range.

Larger tiles, tiles with deep ribs on the back, and ungauged natural stone often need a bigger notch or back-buttering, which uses more mortar than either preset; enter a lower coverage for those. Whatever the notch, the goal is contact: at least 80% of the tile back bedded in mortar in dry areas, and at least 95% in showers, wet areas, and outdoors. Fast-setting thinset in 25 lb bags covers roughly half what a 50 lb bag does.

The spacer estimate is one per tile corner. On a straight grid, four tiles share each corner, so you'll likely use fewer; the margin means you won't stop mid-row to buy more.

How much grout do I need?

Grout fills the joints, so the amount depends on the length of joint per square foot, the joint width, and its depth, which is roughly the tile thickness. Joint length is the big variable: per square foot, 12 × 12 tile has about 24 in of joint, 12 × 24 tile about 18 in, and 4 × 4 tile about 72 in. Small tile with wide joints can need several times the grout of large-format tile with narrow joints over the same floor.

Because grouts differ in density and packaging, use the coverage chart on the grout bag or the manufacturer's online grout calculator with your exact tile size, thickness, and joint width. A single bag often does a small bathroom floor in large tile, while a mosaic shower can take several.

How much does tile cost per square foot?

Rough 2026 US ranges (prices vary by region, so get local quotes): ceramic tile runs about $1–$5 per sq ft and porcelain about $3–$10 per sq ft. Professional installation labour is often roughly $4–$12 per sq ft on top of that, with large-format tile, patterned layouts, and subfloor or wall preparation at the higher end.

For the 110 sq ft worked example, porcelain alone would be roughly $330–$1,100 and installed labour for the 100 sq ft floor roughly $400–$1,200, before thinset, grout, backer board, and trim pieces. Quote the area including waste for materials and the room area alone for labour. If you're pricing several rooms, the flooring calculator for laminate and vinyl plank estimates cartons for the rooms you won't tile.

Tips for tiling

• Dry-lay a row in each direction before mixing thinset, so you can shift the layout and avoid slivers under an inch wide at walls and doorways.
• Check that every carton carries the same shade and lot code, and keep one unopened carton (or a few loose tiles) for future repairs, since discontinued styles are hard to match.
• Mix only as much thinset as you can use within its pot life, and lift a tile now and then to check coverage on the back.
• For a tiled backsplash or wainscot, the paint calculator for the wall above handles the remaining wall area.

Sources

The formulas on this page come from the published research below. Last updated October 10, 2026. This calculator gives estimates for general information. It isn't medical advice, so check anything important with a qualified professional.

1. Custom Building Products. CustomBlend Economical Non-Modified Thin-Set Mortar — coverage chart.Used for: Mortar coverage per 50 lb bag by trowel notch size