Tile Calculator
Tiles, boxes, and cost for floors and walls from area and tile size.
What it does
Tile math has two roundings, and both cost money. Area plus a cuts allowance divided by tile size gives the tile count, rounded up. That count divided by tiles per box gives boxes, rounded up again. Skipping either rounding is how jobs stall one box short on a Sunday.
The tool above runs both steps from area, tile size, waste share, and box quantity. It returns tiles, boxes, and cost at your box price.
Grout lines barely move the count. A sixteenth inch joint across a room shifts totals by low single percents, well inside the waste share. Layout moves it more: diagonal patterns and staggered planks burn extra cuts, while straight grids on big tile sip material.
Order the spare box even when the math looks clean. Manufacturers rotate dye lots, and a future cracked tile demands the same shade, not a close one.
How to use
- Switch the unit system first: imperial for feet and inches, metric for meters and centimeters.
- Measure the area in square feet, subtracting nothing small.
- Enter tile length and width in inches.
- Set waste: 10% for straight rooms, 15% for angles, diagonals, or small baths.
- Read boxes, buy them sealed from one lot, and keep one spare.
Formula
- tile ft2
- One tile area in square feet. A 12x12 covers exactly 1 ft2.
- waste
- Cuts, breakage, and misprints as a rate. 10% means multiply by 1.10.
- ceil
- Round up. Half tiles at edges still consume whole ones.
- per box
- Tiles sealed in one box, printed on the label.
Rectangular tiles follow the same path with length times width. Mosaics on sheets count by sheet area instead: each sheet covers its stated square footage, usually 1 ft2.
Worked example
Example: 120 ft2 floor, 12x12 tile, 10% waste, 10 per box
Bathroom area 120 ft2, square foot tiles, 10% cuts, boxes of 10 at $35.
- One tile: 12 x 12 / 144 = 1 ft2.
- With waste: 120 x 1.10 = 132 ft2 to cover.
- Tiles: 132 / 1 = 132 tiles.
- Boxes: 132 / 10 = 13.2, round up to 14 boxes.
- Cost: 14 x $35 = $490.00 before adhesive, grout, and sealer.
Reference table
| Tile | Covers each | Per ft2 |
|---|---|---|
| 4x4 in | 0.11 ft2 | 9 tiles |
| 6x6 in | 0.25 ft2 | 4 tiles |
| 12x12 in | 1.00 ft2 | 1 tile |
| 12x24 in | 2.00 ft2 | 0.5 tiles |
| 24x24 in | 4.00 ft2 | 0.25 tiles |
Limits
- Flat area math. Borders, medallions, and mixed sizes need separate passes.
- Grout width ignored. Wide joints on tiny tile add a few percent.
- Waste is a guess from experience, not a guarantee for tricky cuts.
- Adhesive, grout, backer board, and labor sit outside tile cost.
Common mistakes
- Buying exact tiles with no cuts share, then breaking three on the saw.
- Mixing dye lots across boxes, which shows as shade bands.
- Measuring the room but tiling around a vanity that later moves.
- Skipping the spare box to save little, then hunting it for years.
- Starting layout from the wall instead of center, leaving slivers.
Try it yourself
Quick checks. Answers sit tucked under each question.
60 ft2 backsplash, 3x6 in subway tile (0.125 ft2 each), 15% waste. Tiles?
60 x 1.15 = 69 ft2. 69 / 0.125 = 552 tiles.
552 tiles at 20 per box. Boxes?
552 / 20 = 27.6, so 28 boxes.
Questions
How much extra tile should I buy?
Ten percent for straight rooms, fifteen for diagonals, angles, or small baths with many cuts.
Do grout lines change the count?
Barely at normal widths. Layout and cuts move the number far more than joints.
Can I return extra boxes?
Often yes for sealed full boxes within store windows. Keep receipts and one spare box back.
How do I tile around obstacles?
Measure the full area, then cut to fit. Small pipes and vents rarely justify subtracting area first.
What about wall tile weight?
Big heavy tile needs the right adhesive and flat walls. Check the tile weight rating before large formats.
Should boxes match dye lots?
Yes. Buy all boxes from one lot code and mix tiles across boxes while setting.