Flooring & Tile
Tile Calculator
Enter your floor or wall dimensions in feet and your tile size in inches to get the tile and box count to buy, with grout joints and wastage included.
Formula tested · Local units · No sign-up
Project inputs
Enter measurements
Use your preferred units. Results update automatically.
Show the calculation methodFormula, conversions, rounding, and assumptions+
Each tile occupies its own size plus one grout joint: a 12 × 12 in tile with a 1/8 in joint takes up 12.125 × 12.125 = 147.02 sq in, about 1.021 sq ft. The area is divided by that footprint to get the exact tile count.
A wastage allowance is then added for cuts, breakage and spares — 10% is typical for a straight lay, 15% for diagonal patterns — and the result is rounded up to a whole tile, then up again to whole boxes when you enter the tiles-per-box figure from the box label.
Real-world example
Worked example: 10 ft × 8 ft floor, 12 × 12 in tiles, 1/8 in joints
- Area: 10 × 8 = 80 sq ft.
- Tile footprint: (12 + 0.125) × (12 + 0.125) = 147.02 sq in ≈ 1.021 sq ft.
- Exact count: 80 ÷ 1.021 = 78.36 tiles.
- Add 10% wastage: 78.36 × 1.10 = 86.19 → round up to 87 tiles.
- Boxes of 10: 87 ÷ 10 = 8.7 → round up to 9 boxes.
Buy 9 boxes (90 tiles). At an example price of $45 per box with 8% sales tax, that's $405.00 + $32.40 = $437.40.
Before you start
How to measure
- Measure the room's length and width in feet at the widest points; for L-shaped rooms, split into rectangles and add the areas in direct-area mode.
- Take the tile size and tiles-per-box count straight from the box label — nominal 12-inch tiles are sometimes slightly under 12 inches.
- Grout joints are commonly 1/8 in (0.125) for floor tile; rectified tile is often laid with tighter 1/16 in joints — enter what your installer plans to use.
Local guidance
Notes for United States
- US tile is sized in inches — 12×12, 12×24, 18×18 floor tile and 3×6 subway wall tile are the common formats — and sold by the box with the coverage printed in square feet.
- Boxes state both tiles per box and sq ft per box; this calculator works from tiles per box, so use that figure from the label.
- Sales tax varies by state and locality and is entered manually; keep at least a few spare tiles from the same dye lot for future repairs.
Quick reference
Common US tile sizes (nominal)
| Format | Size | Typical use |
|---|---|---|
| Square floor | 12 × 12 in | Bathrooms, kitchens, entries |
| Plank / large format | 12 × 24 in | Open floors, showers |
| Large square | 18 × 18 in | Larger rooms |
| Subway | 3 × 6 in | Backsplashes, shower walls |
Nominal sizes for planning — actual dimensions and tiles per box are on the box label.
Good to know
Common mistakes to avoid
- Ignoring the grout joint — over a large floor the joints add up to noticeably fewer tiles than a joint-less division suggests.
- Ordering with no wastage allowance: every cut row, broken tile and future repair comes out of the same dye lot.
- Using 10% wastage for a diagonal or herringbone lay that realistically consumes 15% or more.
- Buying a later batch to top up — dye lots vary, so order everything at once.
Need help?
Frequently asked questions
How many 12×12 tiles do I need for 100 square feet?
With a 1/8 in grout joint each tile occupies about 1.021 sq ft, so 100 ÷ 1.021 = 97.9 tiles exactly. Adding 10% wastage gives 107.7, so buy 108 tiles.
How much extra tile should I buy for wastage?
10% is the usual planning allowance for a straight lay; use 15% for diagonal or herringbone patterns, small or irregular rooms, and large-format tile where each miscut costs more area.
Does the box price include grout and thinset?
No — adhesive (thinset), grout, spacers and trim are all separate. This calculator estimates tile only; enter your supplier's box price for the tile cost.
Keep planning
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About this calculator
- Written by:
- BuildMeasure Editorial Team
- Technically reviewed by:
- Pending independent technical reviewer (formula unit-tested; see methodology)
- Last reviewed:
- 2026-07-16
- Formula version:
- 1.0.0
- Region reviewed for:
- United States
- Spotted an error?
- Report a correction
Methodology
- The area to tile comes either from length × width or from a directly entered area. All arithmetic runs internally in SI units (metres and m²); regional units (inches, mm, ft²) are converted exactly on the way in and out.
- Each tile's effective footprint is (tile length + grout gap) × (tile width + grout gap) — the grout joint is counted once per tile, which is how a repeating grid actually consumes floor area.
- Tile count = area ÷ footprint, multiplied by (1 + wastage %), then rounded UP to a whole tile. When you enter tiles per box, boxes = tile count ÷ tiles per box, rounded UP to a whole box.
- The cost estimate multiplies boxes (or tiles, when no box size is given) by the price you enter, then applies the tax rate you enter. No prices are built in.
- The formula is covered by automated unit tests, including hand-calculated worked examples, and is versioned (see formula version on this page).
Sources & standards
- Unit definitions: 1 in = 25.4 mm and 1 ft² = 0.09290304 m² (exact definitions).
- Wastage allowances: 10% straight lay / 15% diagonal are standard planning allowances; confirm with your installer.
This tool provides a material estimate for planning purposes only. It is not a quotation, and it does not account for layout pattern, substrate preparation, adhesive or grout quantities. Confirm quantities, box coverage and batch numbers with your tile supplier before ordering.