Tile
calculator.
Find how many tiles and boxes a floor or wall needs, with the grout joint counted, areas you won't tile taken out, and a waste allowance that fits your layout. It works in feet and inches or in meters and centimeters.
To tile 120 sq ft with 12 × 12 in tiles and 0.125 in joints, you need 118 tiles before waste and 130 tiles with a 10% allowance, or 9 boxes.
- Tiles to buy (with 10% waste)
- 130
- Tiles before waste
- 118 (117.539 exactly)
- Tiles per sq ft
- 0.97949
- Area to tile
- 120 sq ft
- Area to buy
- 132 sq ft
- Boxes
- 9 × 15 sq ft = 135 sq ft
footprint = (12 + 0.125) × (12 + 0.125) in = 147.01563 in² = 1.0209418 sq ft; tiles = 120 ÷ 1.0209418 = 117.53853; × 1.1 = 129.29238 → 130Every tile,
every box.
- Tiles = area to tile ÷ ((tile length + joint) × (tile width + joint)), because each tile covers its own face plus half the joint on every side.
- Tiles to buy = that count × (1 + waste ÷ 100), rounded up to a whole tile. Left blank, waste is 10% for a straight lay, 15% for a diagonal and 20% for herringbone; type your installer's figure to override it.
- Boxes = area to buy ÷ coverage per box, or tiles to buy ÷ tiles per box, rounded up to a whole box.
- Areas you won't tile, such as a tub, cabinet base or window, are subtracted first. The method counts area, so it cannot see where a particular cut falls.
How do you calculate how many tiles you need?
Find the area, divide it by the area one tile takes up including its grout joint, then add a waste allowance. A 12 × 10 ft kitchen floor is 120 sq ft. A 12 × 12 in tile with a 1/8 in joint takes up 12.125 × 12.125 = 147.02 in², or 1.021 sq ft. 120 ÷ 1.021 = 117.5, so the floor needs 118 tiles before waste, and 130 once 10% is added.
footprint = (tile length + joint) × (tile width + joint)
tiles = area ÷ footprint × (1 + waste ÷ 100), rounded upHow much extra tile should you buy?
Extra tile covers cuts, breakage and future repairs. Fireclay Tile, a tile maker, asks customers to order at least 15% extra for standard patterns and at least 20% for herringbone, chevron and other complex layouts. For a simple straight lay of machine-made tile, 10% is a common planning figure, and the calculator uses it when you leave the waste box blank.
Buy all your tile at once. Tile from a later production lot can differ slightly in shade and size, so a box bought months later may not match. Keep a few spare tiles for repairs.
Why does a diagonal or herringbone layout need more tile?
In a straight lay, a cut tile at one wall often leaves a piece wide enough to finish the opposite wall. Set the same tile at 45° and nearly every tile that meets a wall is cut on the diagonal. The triangular offcuts seldom fit anywhere else, and a 12 in tile now spans almost 17 in along the wall. Herringbone adds angled cuts at the end of every row. On the 120 sq ft floor above, 15% instead of 10% means 136 tiles instead of 130; at 20%, 142.
Does the grout joint change how many tiles you need?
Yes, and more with small tiles. With a 1/8 in joint, a 12 × 12 in tile takes up 2.1% more area than its face, so 120 sq ft needs about 118 tiles rather than 120. A 3 × 6 in subway tile with a 1/16 in joint takes up 3.1% more. The difference is small but it adds up over a large floor, and it explains why box labels, which state tile face area, slightly overstate how many boxes you need.
How many boxes of tile do you need?
Divide the area to buy by the coverage printed on the box, then round up. 120 sq ft plus 10% is 132 sq ft; at 15 sq ft a box that is 8.8, so buy 9 boxes. If the box gives a tile count instead, divide the tiles to buy by the tiles per box. A 5 × 8 ft shower wall in 3 × 6 in subway tile needs 342 tiles with 10% waste, which is 9 boxes of 40.
How do you measure a room with a tub, island or cabinets?
Measure the whole floor or wall as rectangles, add them up, then subtract what will not be tiled. A 10 × 8 ft bathroom is 80 sq ft; take off a 5 sq ft vanity base and you tile 75 sq ft. With 12 × 24 in tiles and a 1/8 in joint that is 37 tiles before waste and 41 with 10%.
Worked examples.
Kitchen floor, straight lay
A 12 × 10 ft floor in 12 × 12 in tile with 1/8 in joints, 15 sq ft per box.
130 tiles · 9 boxes
Load this exampleBathroom floor around a vanity
A 10 × 8 ft bathroom minus a 5 sq ft vanity, 12 × 24 in tile at 1/8 in, 15.5 sq ft boxes at $3.25 per sq ft.
41 tiles · 6 boxes
Load this exampleHerringbone living area
200 sq ft less a 20 sq ft island, 12 × 24 in plank tile at 3/16 in, herringbone.
106 tiles · 15 boxes
Load this exampleMetric floor on the diagonal
A 4 × 3 m room in 60 × 60 cm porcelain with 3 mm joints, laid at 45°, 1.44 m² boxes at €30 a box.
38 tiles · 10 boxes
Load this exampleSubway tile shower wall
A 5 × 8 ft wall in 3 × 6 in subway tile with 1/16 in joints, 10% waste, 40 tiles per box at $0.50 a tile.
342 tiles · 9 boxes
Load this exampleWhat this calculator
does not do.
- It counts by area. It does not plan where cuts fall, so an awkward room, many corners or a large tile can waste more than the allowance.
- The 10%, 15% and 20% waste figures are planning allowances, not rules. Handmade, natural stone, large-format and mosaic tile often need more; follow your installer or the tile maker.
- It does not estimate grout, thinset, backer board or trim. Use the coverage chart on the product you buy.
- Box coverage is taken from the label, which states tile face area, so the box count can be one box generous.
Common questions.
How many 12 × 12 tiles are in 100 square feet?
With no joint, exactly 100. With a 1/8 in joint, 100 ÷ 1.021 = 97.9, so 98 tiles before waste and 108 with 10% extra.
How many 12 × 24 tiles do I need for 100 square feet?
Each covers 2 sq ft, so 50 with no joint. With a 1/8 in joint, 100 ÷ 2.031 = 49.2, so 50 before waste and 55 with 10%.
Should I add 10% or 15% for tile waste?
About 10% suits a simple straight lay of machine-made tile. Use 15% or more for a diagonal layout, handmade tile or a room with many corners, and at least 20% for herringbone.
Do I count the grout lines when estimating tile?
Yes. Add the joint width to the tile's length and width before dividing. Leaving it out slightly overestimates the tiles, more so with small tiles and wide joints.
Does this work for wall tile?
Yes. Enter the wall's width as the length and its height as the width, and subtract windows or a tub as the area not tiled.
- Fireclay Tile: FAQs (ordering and overage) — at least 15% overage for standard patterns, at least 20% for herringbone and other complex patterns
- Fireclay Tile: Tile School, doing the math — measure in sections and add them; 15–20% overage, a minimum of 20% for patterns with more cuts
- NIST Guide to the SI, Appendix B.9: conversion factors — 1 in = 0.0254 m and 1 ft² = 0.09290304 m², both exact
Every length is converted to meters with exact NIST factors, so the same job entered in feet and inches or in meters and centimeters gives the same count. The tile footprint includes the joint, results are rounded up only at the end, and box counts round up to whole boxes. For a straight lay of a plain rectangle, the calculator also counts the grid of whole and cut tiles row by row as a check. Tests cover hand-worked jobs in both unit systems, 300 random rooms checked for unit independence and for counts that rise with waste and fall with wider joints, and every invalid input.
Built and reviewed by CalculatorLab against the sources above; every worked example on this page is re-checked by our automated test suite before each release. How we build and check calculators. Found a problem? Tell us.