Tile & Flooring Coverage Calculator
Calculate tiles needed, waste, boxes to buy, and total cost β for any room size.
Results
How to Use This Tile Calculator
Enter your room's length and width in your preferred unit (feet, meters, or inches), then enter the individual tile dimensions. Set a waste percentage using the slider β 10% is standard for straight-lay patterns, 15% for diagonal, and up to 30% for complex cuts or irregular rooms. Optionally add tiles-per-box and price-per-box to get full cost estimates. Hit Calculate Tiles and see your complete breakdown instantly.
Use the Multiple Rooms tab to sum up totals across a kitchen, bathrooms, and hallways in one shot.
Why This Matters
Buying too few tiles means a costly second trip to the store β and there's no guarantee the same batch will match (tiles are manufactured in dye lots, and color variation between batches is real). Buy too many and you've wasted money on materials you'll store in a garage forever.
A standard 12Γ12 ft bathroom floor covers 144 sq ft. With 12"Γ12" tiles and a 10% waste factor, you'd need 159 tiles. If those tiles come 10 per box at $35 each, that's 16 boxes β a $560 purchase. Getting this wrong by even one box can mean a wasted trip or a visible mismatch. For a diagonal installation, bumping waste to 15% adds 2 more boxes and ~$70 to protect yourself. A kitchen with an island or L-shaped cuts should use 20%+ to account for extra cuts around edges and obstacles.
How It's Calculated
The calculation follows these steps:
- Room Area = Length Γ Width (converted to sq ft or sq m consistently)
- Tile Area = (Tile Length + Grout Joint) Γ (Tile Width + Grout Joint) β grout is included in each tile's footprint
- Base Tile Count = Room Area Γ· Tile Area
- With Waste = Base Count Γ (1 + Waste% Γ· 100), rounded up to whole tiles
- Boxes Needed = βTiles With Waste Γ· Tiles Per Boxβ (ceiling, always round up)
- Total Cost = Boxes Needed Γ Price Per Box
All units are converted to inches internally for precision before computing areas.
Tips & Common Mistakes
- Always round boxes UP β you can never buy half a box, and stopping mid-job because you're 3 tiles short is frustrating.
- Match dye lots β buy all tiles at once, and keep 5β10% extra in storage for future repairs.
- Measure twice β for L-shaped or irregular rooms, break the space into rectangles and calculate each separately using the Multi-Room tab.
- Account for obstacles β islands, columns, bathtubs, and fireplaces reduce your floor area. Subtract those footprints from the room area before calculating.
- Grout joint size matters β a 3/16" joint on 12"Γ24" tiles adds roughly 2β3% to the total area you're covering. Always include it.
Frequently Asked Questions
How much waste percentage should I use?
Use 10% for standard straight-lay patterns in regular rectangular rooms. Go to 15% for diagonal or herringbone patterns, and 20β30% for complex rooms with many cuts, L-shapes, or curves. If you're a beginner tiler, add an extra 5% to account for mistakes during cutting.
Should I include grout joint width in my calculation?
Yes, and this calculator does it automatically. A 1/8" grout joint on a 12"Γ12" tile increases the effective tile footprint slightly β across hundreds of tiles, this adds up. Ignoring grout can cause you to buy 2β4 extra tiles you don't actually need.
What if my room is not a perfect rectangle?
Break the room into rectangular sections and use the Multiple Rooms tab β one entry per rectangle. Add up all sections to get total tiles and cost. This works well for L-shaped rooms, rooms with closets, and open-plan spaces.
Can I use this for wall tiles too?
Absolutely. The same square-footage math applies. Enter your wall height as "length" and wall width as "width." For a backsplash, use the exact dimensions of the backsplash area. Just subtract any windows or outlets from the area if they're large enough to matter.