Tile Calculator
Tile count
Results
| Floor area | — |
|---|---|
| Tiles needed | — |
| Boxes | — |
How to Use This Tile Calculator
Tile runs out at the worst possible moment—usually halfway through the last row against the back wall where the store is already closed. I have seen DIY installers buy exactly the net area in 12×12 tiles and come up six short because of diagonal cuts around a toilet flange. This calculator totals room area, divides by tile size, applies your waste percentage, and converts to whole boxes based on what the box label actually says.
Enter room length and width with independent unit selectors (feet, meters, inches, yards). Enter tile length and width the same way—most floor tile is sold in inches or centimeters on the spec sheet even when the room was measured in feet. Set waste percentage (10% is a safe starting point for straight layouts; bump to 15% for diagonal or herringbone patterns). Enter tiles per box from your supplier's packaging.
Results show floor area in ft² and m², tile count including waste, and boxes rounded up. For the room dimensions themselves, cross-check with our Square Footage Calculator if the space is not a simple rectangle.
Tile Calculator Formulas and Practical Applications
Tile math is area division with a safety margin—like cutting a sheet cake into equal slices and keeping a few extras for crumbs.
Step 1: Room and tile areas
Room Area = Length × Width
Tile Area = Tile Length × Tile Width (converted to square feet internally)
Step 2: Tiles with waste
Tiles Needed = Ceiling(Room Area ÷ Tile Area × (1 + Waste ÷ 100))
Step 3: Boxes
Boxes = Ceiling(Tiles Needed ÷ Tiles per Box)
Example: a 10 ft × 12 ft bathroom (120 ft²) with 12 in × 12 in tiles (1 ft² each) and 10% waste needs 132 tiles. At 12 tiles per box, that is 11 boxes—always rounded up so you are not one partial box short.
Grout joint width slightly reduces tile coverage; most installers account for that inside the waste percentage rather than adjusting nominal tile size.
Standard Units and Conversion Tables
Common floor tile formats and planning notes:
- 12 × 12 in: 1 ft² per tile—the baseline many box counts assume.
- 12 × 24 in: 2 ft² per tile; fewer pieces but heavier boxes.
- 18 × 18 in: 2.25 ft² per tile.
- Waste: 10% straight lay; 15% diagonal; 20% for intricate patterns or brittle material.
Frequently Asked Questions
Should I include grout lines in tile size?
Use the nominal tile dimensions printed on the box. Standard waste percentages (10–15%) usually cover grout joint area and cut loss together. For unusually wide grout lines or thick spacers, increase waste slightly.
How many extra tiles should I keep after installation?
Save at least one full box when possible for future repairs. Dye lots change between production runs—a replacement tile from the same batch is nearly impossible to match years later.
Can I use this for wall backsplash tile?
Yes. Measure the backsplash rectangle—length times height between counter and cabinet—and enter those dimensions. Small mosaic sheets may list coverage per sheet on the label; compare that to our tile-area output if sheets differ from individual piece sizes.
Disclaimer. Informational only—not installation or design advice. Patterns, grout lines, and irregular rooms need extra tile—measure on site.