Tile Calculator
Calculate how many tiles you need for your floor or wall project. Includes waste calculation and box estimates for any tile size.
Reviewed by the Calcura editorial team · Last reviewed
- Question
- How many tiles do I need?
- Answer
- tiles = (floor_area / tile_area) × (1 + waste%). TCNA recommends 10% waste for straight-lay installations, 15% for diagonal, and 20% for herringbone or offset. A 120 ft² floor with 12" × 12" (1 ft²) tiles at 10% waste needs 120 × 1.10 = 132 tiles. Always round up to the next full box — tile dye lots vary, and returning half a box is a hassle.
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- Formula
tiles = (area / tile_size) × (1 + waste%)- Caveats
- Buy extra from the same lot upfront — matching lots later is nearly impossible.
- Diagonal and herringbone layouts cut more tiles on the edges; bump waste to 15–20%.
- For walls with doorways/windows, subtract their area from the total before applying waste.
What This Calculator Does
Computes the number of tiles and boxes needed to cover a rectangular floor or wall area given the room dimensions, tile dimensions, and a waste-overage percentage. Returns tile count (rounded up), assumed 10-tile boxes, and the raw square footage. Uses the TCNA recommended 10% waste floor for straight-lay installations.
When To Use This Calculator
Tiling a rectangular bathroom floor
8 × 10 ft with 12×12" tiles: 80 ft² ÷ 1 ft² = 80 tiles × 1.10 waste = 88 tiles → 9 boxes of 10.
Estimating a kitchen backsplash
10 ft × 18 in = 15 ft² with 3×6" subway tiles (0.125 ft² each): 15 / 0.125 = 120 tiles × 1.15 waste = 138 tiles.
Laying a porcelain plank floor in a main area
14 × 20 ft = 280 ft² with 6×36" planks (1.5 ft² each): 187 planks × 1.15 = 215 → 22 cartons at 10 planks each.
Ordering replacement tiles for a discontinued pattern
Match a 20 ft² repair area — buy the full 15% overage anyway since getting more later is often impossible.
How It Works
Tile count is room area (in the same units) divided by single-tile area, then multiplied by (1 + waste fraction) and rounded up. Box count assumes 10 tiles per box — a close approximation for the common 12×12 size, but off for larger or smaller tiles, so check your product's box quantity. Metric inputs are converted internally so the math is performed in consistent units before the final round-up. Waste is covered per Tile Council of North America guidance: 10% for straight-lay, 15% for diagonal or running bond, and up to 20% for herringbone, chevron, or small-tile patterns with many cuts.
Formula
tiles = ceil((room_area / tile_area) × (1 + waste_pct / 100)) | boxes = ceil(tiles / tiles_per_box)Real-World Example
Scenario
Remodeling a 10 × 13 ft kitchen with 12×24" rectified porcelain laid straight. Each tile is 2 ft². Product is sold 5 tiles per carton. Straight-lay installation with normal cuts around cabinets and an island footprint of 2 × 6 ft that won't be tiled.
Calculation
Tileable area: (10 × 13) − (2 × 6) = 118 ft². Tiles needed: 118 / 2 = 59 tiles × 1.10 = 64.9 → round up to 65. Cartons: 65 / 5 = 13 cartons of 5 tiles each.
Result
Order 13 cartons (65 tiles, 130 ft² of coverage). The 10% waste absorbs the irregular cuts around the island and appliances plus a few breakage losses.
Common Mistakes to Avoid
Mistake: Ignoring grout line width on small tiles
Solution: On tiles under 4 inches, 1/8" grout lines add up — actual tile coverage can be 3–5% less than nominal. Increase waste by 5% for small-format tile.
Mistake: Buying tiles across multiple shipments
Solution: Dye-lot variation is real for ceramic and porcelain. Always order the full quantity (including overage) in one shipment from the same lot number.
Mistake: Using 10% waste for diagonal or herringbone layouts
Solution: Diagonal patterns typically waste ~15%; herringbone often wastes 20% due to the edge cuts on every row. Increase the waste % input, don't eyeball it.
Mistake: Not ordering attic stock for future repairs
Solution: Include at least one extra box beyond the waste calculation. Tiles discontinue or lot-shift within a year — future damage repairs need matching material.
Related DIY tools
When This Isn't the Right Tool
Curved, angled, or heavily-cut rooms
Use instead: Length × width undercounts irregular shapes. Break the space into rectangles or have a pro do a takeoff from drawings.
Mosaic sheets priced per sheet
Use instead: Mosaic sheets are sold as 12×12" mesh units typically containing dozens of chips. Compute sheet area, not individual chip area.
Mixed-material or inset designs
Use instead: Multiple tile sizes and inlays can't be aggregated into one calc. Compute each material's area separately and sum.
How to Verify This Calculation
Sanity check: a 10 × 10 ft room with 12×12" tiles is exactly 100 tiles at zero waste. 100 × 1.10 = 110 tiles = 11 boxes of 10. If results are dramatically off, tile dimensions may be in feet instead of inches (or cm vs m).
Sources
- Tile Council of North America — Handbook for Ceramic, Glass, and Stone Tile Installation — Industry-standard reference for waste percentages, pattern overages, and substrate requirements.
- ANSI A108 — American National Standards for tile installation — US consensus installation standards including cut tolerances and lippage that drive waste planning.
- ISO 13006 — Ceramic tiles: definitions, classification, characteristics, and marking — International tile-sizing standard underlying the nominal vs actual tile dimensions used in planning.
- BIPM — SI Brochure — Basis for the metric-to-imperial conversions (1 in = 2.54 cm exact, 1 m² = 10.764 ft²).
Reviewed by the Calcura editorial team · Last reviewed