Tile Calculator

About the Tile Calculator

The Tile Calculator estimates how many boxes of tile you need to cover a floor based on the floor dimensions, the tile size, a waste percentage for cuts and breakage, and the tiles-per-box and price-per-box from the retailer's packaging. Enter the floor length and width, pick a standard tile size (4” to 24”), set the waste percentage (typically 10% for straight-lay patterns, 15% for diagonal, 20% for herringbone), and the calculator returns total tiles needed, boxes to buy, leftover tiles, and total cost.

Tile ordering math has several gotchas that catch first-time DIYers. The most common mistake is buying exactly the floor area's worth of tile — with no allowance for cuts, breakage, or future repairs. Tile is sold in full boxes, so you'll almost always have some leftover. The waste percentage compensates for diagonal cuts around obstacles, broken tiles during installation, and pattern-matching for herringbone or chevron layouts. Buying 10-15% extra is the industry standard; some contractors budget 20% for complex patterns.

Always buy all your tile from the same batch (called a “dye lot” or “caliber”) because tiles from different batches can vary subtly in color and size. The leftover tiles from the calculator are worth keeping — they match your floor exactly and are useful for future repairs if a tile cracks or stains. Without matching spares, a single damaged tile can mean replacing the entire floor.

How It Works

Floor area is computed as length × width in square feet. Tile area is (tileSizeInches / 12)² — the size of one tile in square feet. Tiles needed is floorArea / tileArea, rounded up with Math.ceil to ensure you don't end up half a tile short.

For example, a 12×10 foot room is 120 sq ft. A 12-inch tile is 1 sq ft, so you need 120 tiles. A 6-inch tile is 0.25 sq ft, so you need 480 tiles. Smaller tiles mean more total pieces and more grout lines, which affects both material cost and installation labor.

Waste percentage is applied as a multiplier: tiles_with_waste = tiles_needed × (1 + waste/100), again rounded up. For a 120-tile job with 10% waste, that's 120 × 1.10 = 132 tiles. The waste covers diagonal cuts at corners, half-tiles at edges, broken tiles during installation, and pattern-matching losses.

Boxes to buy is Math.ceil(tiles_with_waste / tiles_per_box). Tile is sold in full boxes — you can't buy a partial box. If you need 132 tiles and there are 10 per box, you buy 14 boxes (140 tiles total), leaving 8 leftover tiles. Total cost is boxes × price_per_box.

The cost-per-square-foot calculation divides the total cost by the actual tile area purchased (boxes × tiles per box × tile area). This is the most honest cost comparison metric when shopping tile — a $35 box of ten 12-inch tiles ($3.50/sq ft) is more expensive than a $50 box of twenty 12-inch tiles ($2.50/sq ft), even though the per-box price is lower.

Worked Examples

Default: 12×10 room (120 sq ft), 12-inch tiles, 10% waste, 10 tiles per box at $35. Tiles needed = 120, with waste = 132, boxes = 14 (140 tiles), leftover = 8, cost = $490. Cost per sq ft = $490 / (140×1) = $3.50/sq ft.

For the same 12×10 room with 6-inch tiles (smaller mosaic look): tiles needed = 480, with waste = 528, boxes at 25 per box = 22 (550 tiles), leftover = 22. If box price is $30, total cost = $660, or $4.40/sq ft. Smaller tiles cost more for the same area due to the premium for smaller cuts and more grout.

For a 16×14 bathroom (224 sq ft) with 18-inch tiles (2.25 sq ft each), 15% waste for diagonal layout: tiles needed = 224/2.25 = 99.6 → 100, with waste = 115, boxes at 5 per box = 23 (115 tiles exact), cost at $45/box = $1,035.

For a herringbone pattern (which has more waste): same 12×10 room, 12-inch tiles, 20% waste. Tiles needed = 120, with waste = 144, boxes = 15 (150 tiles), leftover = 6. The herringbone pattern's zig-zag cuts produce more waste than straight lay.

Comparing tile prices: 12-inch tile at $35/box of 10 = $3.50/sq ft. Same tile at $50/box of 20 = $2.50/sq ft. Larger box sizes often represent better per-square-foot value, but check the box dimensions — some “bulk” packaging hides a higher per-tile cost.

When to Use This Tool

• Budgeting tile for a kitchen, bathroom, or hallway floor before visiting a tile showroom.
• Comparing tile sizes (e.g., 12-inch vs 18-inch) to see which gives the best cost-per-sq-ft.
• Accounting for waste on complex patterns (herringbone, chevron, diagonal) where cuts produce more offcuts.
• Estimating spares to keep on hand for future tile repairs (cracks, stains, water damage).
• Comparing retailer prices by computing cost per square foot rather than per box.
• Verifying a contractor's tile order to ensure they're buying enough (and not over-ordering to inflate the bill).
• Planning a backsplash or accent wall (compute wall area, not floor).

Limitations & Disclaimer

This calculator assumes a simple rectangular floor and does not subtract openings (cabinets, islands, fixtures) automatically — compute the floor area minus obstacles manually for irregular rooms. The waste percentage is a general guideline; complex patterns (herringbone, chevron, Versailles) and irregularly shaped rooms may need 25%+ waste. Tiles-per-box and price-per-box vary by retailer and product line — verify on the actual product packaging. Grout, thinset mortar, sealers, and underlayment are not included and require separate estimation. Natural stone tile may vary in size and color between boxes, requiring additional sorting. Always buy tile from the same dye lot (caliber) to avoid visible color mismatches. See our disclaimer for full terms.

Frequently Asked Questions

Last updated: July 21, 2026  ·  Author: HT99 Tools Editorial Team  ·  Reviewed by: HT99 Tools Editorial Team