Tile Calculator
Calculate tiles needed for floors or walls with grout spacing and waste percentage.
Reviewed by Aygul Dovletova · Last reviewed
Using the Tile Calculator
Work out how many tiles to order for a floor, backsplash, shower surround, or accent wall. The tool bakes in grout-joint width and a waste factor so you walk into the tile shop with the correct box count, not a guess.
- Input mode - pick length × width for rectangular areas, or direct-area entry if you already have a square-footage number.
- Tile dimensions - width and height in inches. Handles everything from 1-inch mosaic chips to 24 × 48 inch porcelain slabs.
- Grout joint - default 1/8". Subway usually goes at 1/16", stone at 3/16" to 1/4", rectified porcelain at 1/32" to 1/16".
- Waste percentage - 10% for straight lay on square rooms, 15% for diagonal, 20% for herringbone, 25% for a first-time tiler working around a toilet flange.
What the Calculator Is Actually Doing
Real tile coverage per unit is (width + grout) × (height + grout), not raw tile area, because each tile claims half of the grout line on every side. For a 12 × 12 tile at 1/8 inch grout, each tile covers 12.125 × 12.125 = 1.021 sq ft. Divide floor area by that number to get tile count before waste, multiply by 1 + waste%, then Math.ceil. Tile ships in cartons of 6-12 pieces depending on size; the calculator stops at the tile count so you can do the box-rounding yourself once you know the SKU.
Why Grout Width Actually Matters
On a small backsplash, grout contribution is negligible. On a 200 sq ft floor with 4-inch tiles at 1/4-inch grout, the grout joints claim roughly 12% of the surface - 30-40 tiles difference over the job. Wider joints mean fewer tiles; narrower joints mean more. Rectified large-format porcelain at 1/32-inch joints pushes tile count higher than beginners expect.
When You Reach for This Tool
- Shopping for a bathroom floor retile and you need 12 × 24 porcelain box count.
- Planning a kitchen backsplash with 3 × 6 subway tile, deciding between 2 and 3 boxes.
- Pricing a shower surround where you need wall tile count plus floor mosaic count separately.
- Diagonal-lay patterns where the higher waste makes the cost estimate different.
- Checking whether a contractor's material quote is reasonable.
Edge Cases and Waste Sources
Waste comes from five predictable places: perimeter cuts (every wall forces a cut tile, and offcuts rarely match up), penetrations (toilet flanges, drains, pipe stubs), pattern matching (running bond and herringbone need extra tile for course ends), breakage (porcelain is brittle, especially at cut edges - 2-3% even for a pro), and dye-lot insurance. The 10% default handles 1-3; 15% handles all five on a simple layout; 20-25% is realistic for a first-time DIYer on a complex pattern.
Tile Standards and Terminology
Porcelain is denser than ceramic (water absorption under 0.5% per ANSI A137.1), more frost-resistant, and harder to cut. Tile sizes are nominal, not precise: a "12 × 12" ceramic tile measures 11 7/8 × 11 7/8 inches so a 1/8 grout joint yields a 12-inch module. Rectified porcelain is ground to actual size and can be laid with near-invisible joints. PEI ratings (1-5) measure abrasion resistance - PEI 3 for residential floors, PEI 4 for light commercial. DCOF (dynamic coefficient of friction) measures slip resistance; 0.42 or higher is required for interior wet floors.
How It Compares to Alternatives
Tile-store calculators (Daltile, Floor & Decor, Home Depot) tend to ignore grout width and simply divide square footage by printed tile area plus a flat waste - which under-orders on tiles under 6 inches and over-orders on tiles over 18 inches. A tile contractor uses a laser measure and a supplier app that knows exact box counts - better for real jobs. Graph paper with scaled tile drawings is still the most accurate method for bathrooms with curved vanities. This tool lands between: faster than graph paper, more honest about grout than most retail calculators, accurate enough to avoid running short on a rectangular room.
Frequently Asked Questions
What waste percentage should I use for herringbone?
At minimum 15%, realistically 20%, and 25% if you have never laid herringbone before. It creates a 45-degree cut at every wall and at every direction change, and those offcuts only sometimes work on the opposite side. A tight budget plus complex pattern means one extra trip to the tile store, where your dye lot may be gone.
Why does 1/16 inch grout need more tiles than 1/4 inch?
Narrower grout joints mean each tile claims less of the gap, so more tiles cover the same area - about 3% more tile count for a 1/16" joint versus 1/4" on a 12-inch tile. Thinset consumption is driven by trowel size, not grout width. Grout material itself increases noticeably with wider joints.
Does the tool account for running bond or half-drop layouts?
Not directly. A 50% offset running bond of rectangular tiles has no extra material waste versus stack-bond. A 33% offset running bond on large-format plank tile may be required by the manufacturer to avoid lippage; 10% waste still covers it on a rectangular room. Complex geometric patterns like Versailles or pinwheel need a pattern-specific estimator.
Should I add waste before or after rounding up?
The calculator applies waste to the tile count, then rounds up the final number. Applying ceiling first would under-buy on small areas where rounding absorbed the waste buffer. If you are ordering by box, do a second ceiling at the box level: if each box holds 10 tiles and you need 47, buy 5 boxes, not 4 boxes plus loose.
What is a dye lot and why should I care?
Tile is kiln-fired in batches, and colour varies between batches due to glaze chemistry and firing temperature. All tile in one box is from one lot; tile ordered six months later is almost certainly a different lot, with colour differences ranging from imperceptible to obvious under raking light. Always order all boxes in one shipment and keep one unopened box as lot-insurance.
Can I use the tool for mosaic sheets instead of individual tiles?
Yes - enter the mosaic sheet dimensions (typically 12 × 12 inches) and treat each sheet as one "tile." Grout width between sheets matters; the grout within the sheet is already set by the manufacturer on the mesh backing. Waste tends to be lower on floors (cut mesh, not chips) but higher on walls around fixtures.
Is the input sent to a server?
No. The page mounts a Preact component that holds your measurements in memory and recomputes tile count on every keystroke. No API call, no backend logging, no persistence. Refreshing the page clears the form. Copy the estimate to a note before navigating away.
What is the realistic breakage rate during installation?
For a careful homeowner with a wet saw: 3-5% on porcelain, 2-3% on ceramic, 8-12% on natural stone (especially marble and travertine). Breakage happens most at thin strip cuts (under 1 inch) and L-cuts around pipes. The default 10% waste covers normal breakage plus perimeter cuts; bump to 15% if you are doing many small strip cuts.
Do I need extra tile beyond the waste percentage?
Yes. Keep at least one full box, or two to three square feet, of every finished tile surface in your garage for future cracks or plumbing repairs. The calculator's waste covers the current install only. Extra boxes now save the nightmare of matching a discontinued tile in five years.
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