Tile Calculator: How Much Tile Do I Need? (2026)

Tile is sold by the box, but installs are measured in square feet — and almost every DIYer either over-orders by 30% or comes up two boxes short on install day. This tile calculator guide walks through the exact contractor formula, the waste factor for every layout (straight, diagonal, herringbone), and a 2026 cost breakdown for floors, showers, and backsplashes.

The tile calculator formula

Tiles needed = (Area in sq ft ÷ Tile size in sq ft) × (1 + Waste %)

Then convert tiles to boxes by dividing by the tiles-per-box count printed on the carton. Always round up to whole boxes — tile from a different dye lot rarely matches.

How to calculate tile step by step

Step 1 — Measure the area

For floors: Length × Width. For showers and backsplashes: measure each wall separately (Width × Height) and add them together. Subtract large openings like windows, but don't bother with outlets — the cutoffs cover them.

Example floor: a 10 × 12 ft bathroom = 120 sq ft. Example shower: three walls at 3 × 7 ft = 63 sq ft of wall tile.

Step 2 — Convert tile size to square feet

• 12 × 12 in = 1.00 sq ft per tile
• 12 × 24 in = 2.00 sq ft per tile
• 18 × 18 in = 2.25 sq ft per tile
• 6 × 6 in = 0.25 sq ft per tile
• 4 × 4 in (subway/backsplash) = 0.11 sq ft per tile
• 3 × 6 in subway = 0.125 sq ft per tile

Step 3 — Add the right waste factor

This is where most DIYers under-order. Use the layout-based waste factor below, not a generic 10%.

Tile waste factor by layout

• Straight lay, square room — 10%
• Straight lay, irregular room or lots of cuts — 15%
• Diagonal lay (45°) — 15%
• Herringbone or chevron — 20%
• Hexagon, penny round or mosaic sheets — 15%
• Large-format tile (24" or longer) — 15% (more breakage)

Worked example: a 120 sq ft floor laid in 12×24 tile, straight: 120 ÷ 2.00 = 60 tiles. Add 10% waste: 60 × 1.10 = 66 tiles. If the box holds 8 tiles, that's 9 boxes (round up).

How much tile do I need for common projects?

• Standard tub surround (3 walls, 5 ft tub, 6 ft high) — 90 sq ft
• Walk-in shower (3 × 3 ft, 7 ft tall, 3 walls + floor) — 72 sq ft
• Bathroom floor (5 × 8 ft) — 40 sq ft
• Kitchen backsplash (10 linear ft × 18" tall) — 15 sq ft
• Full kitchen floor (12 × 14 ft) — 168 sq ft
• 1,500 sq ft house, all tile floors — 1,500 sq ft + 15% = 1,725 sq ft

Tile cost per square foot (2026)

US averages for materials only — installation runs $7 to $14 per sq ft on top:

• Ceramic — $1 to $5 per sq ft
• Porcelain — $3 to $10 per sq ft
• Natural stone (travertine, slate) — $5 to $15 per sq ft
• Marble — $10 to $40 per sq ft
• Glass mosaic sheets — $7 to $25 per sq ft
• Installed (materials + labor) — $10 to $25 per sq ft typical

For the 120 sq ft bathroom in porcelain at $5/sq ft: ~$660 in tile (9 boxes), $80 in thinset and grout, plus $1,200–$1,700 in labor. Total: $1,940 to $2,440 installed.

Don't forget thinset, grout and underlayment

Per 100 sq ft of tile install, plan for:

• Thinset mortar — one 50 lb bag covers ~80 sq ft with 1/4" notch trowel; large-format tile needs more
• Unsanded grout — 1 bag (10 lb) for joints under 1/8"
• Sanded grout — 1 to 2 bags for joints 1/8" to 3/8"
• Cement backer board — 3 sheets of 3×5 ft for a wet area floor
• Tile spacers — 1 bag of 100 covers a small bathroom

Tile size: which one should I buy?

• Small bathrooms — 12×12 or 12×24 to keep cuts simple
• Large open floors — 24×24 or 24×48 for fewer grout lines
• Showers (walls) — 3×6 or 4×12 subway for classic, 12×24 for modern
• Shower floors — 2×2 mosaic for slip resistance and drain slope
• Backsplashes — 3×6 subway, hexagon, or peel-and-stick mosaic

Frequently asked tile questions

How much extra tile should I buy?

10% for square rooms with straight lay, 15% for diagonal or irregular rooms, 20% for herringbone. Always keep one full box after install for future repairs — dye lots change and matching later is nearly impossible.

How much tile do I need for a shower?

Measure each wall (Width × Height) and add them. A standard 3-wall tub surround at 5 ft wide × 6 ft tall = 90 sq ft. Add 15% waste = 104 sq ft, or about 13 boxes of 12×24 tile.

How do I calculate tile for a backsplash?

Multiply linear feet of countertop by the height of the backsplash (usually 18"). A 10 ft kitchen backsplash = 10 × 1.5 = 15 sq ft. Add 15% for the typical small-tile cuts around outlets = 17 sq ft.

Should I subtract doors and windows?

Subtract anything bigger than 10 sq ft (windows, niches, doorways). Smaller cutouts get absorbed by the waste factor — subtracting them risks under-ordering.

How much does it cost to tile a bathroom?

In 2026, a full bathroom retile (floor + tub surround, ~150 sq ft) runs $2,500 to $5,500 installed depending on tile choice. DIY materials alone: $600 to $1,400.

Use the free tile calculator

Skip the math — punch your room dimensions and tile size into the calculators on our home page and get tiles, boxes, thinset, grout and total cost in one click. The exact contractor formula above is built in, including the right waste factor for your layout.