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CalcBelt

Tile calculator

Find how many tiles and boxes to buy for a floor, wall or shower, plus the grout and thinset, with the right extra for your layout.

Units
Area to tile
Tile

Fractions work: 1/16, 1/8, 3/16.

Used for grout depth.

Layout and supplies
%

Keep a few spare tiles for repairs.

sq ft

On the box label.

Tiles needed

108 tiles

To cover 110 sq ft: 100 sq ft plus 10% extra

Grout
7.2 lb1 bag of 25 lb
Thinset mortar
2 bags50 lb bags, 63 sq ft each

Cost estimate

per sq ft

From the store label.

per sq ft

Labor: $800 (range $300 to $1,500)

Typical US price $3 to $15 per sq ft (Angi, HomeAdvisor, This Old House, October 2026). Large tiles, patterns and removing old floors cost more.

How it's calculated
  1. Area: 100 sq ft; add 10% for cuts and spares: 110 sq ft
  2. One tile plus its grout joint covers 1.02 sq ft
  3. 110 sq ft ÷ 1.02 sq ft = 107.7, rounded up to 108 tiles
  4. Grout (MAPEI's formula): joint length per area × joint width × depth × 1.6 kg/L, plus 10% = 7.2 lb

Estimates use manufacturer data sheets and industry guides (sources). Check local codes and your supplier's figures before you order.

How to use the tile calculator

  1. Measure the floor or wall, or type the area if you already know it.
  2. Enter the tile size, the grout joint and the tile thickness. Fractions such as 1/8 work.
  3. Pick the layout. Diagonal and herringbone patterns need more extra tile for cuts.
  4. Add the coverage per box from the label to count boxes.
  5. Read the tiles, boxes, grout and thinset to buy.

How to calculate tile

Tiles = area × (1 + extra %) ÷ area of one tile with its joint

The joint matters more than people expect. A 12 × 12 in tile with a 1/8 in grout joint takes up 12 1/8 × 12 1/8 in, about 1.02 sq ft. Small tiles with wide joints cover noticeably less than their face size.

Example: a 6 × 9 ft bathroom floor (54 sq ft) with 12 × 24 in tiles and 1/8 in joints, laid straight. One tile and its joint covers 12.125 × 24.125 ÷ 144 = 2.03 sq ft. With 10% extra, 59.4 ÷ 2.03 = 29.2, so 30 tiles.

Extra tile by layout

Layout Extra to add
Straight or brick offset 10%
Diagonal 15%
Herringbone or chevron 20%

Add a little more for rooms with many corners, columns or curves.

How grout is calculated

Grout fills the joints between tiles, so the amount depends on how much joint there is per square foot and how big each joint is. MAPEI publishes this formula:

kg per m² = (A + B) ÷ (A × B) × C × D × 1.6

A and B are the tile length and width, C the tile thickness and D the joint width, all in millimeters. The 1.6 is the grout’s density in kg per liter. The calculator uses the same formula in inches and adds 10% for waste. For a 12 × 12 in tile, 3/8 in thick, with 1/8 in joints, it gives about 0.065 lb per square foot, close to MAPEI’s own chart.

Thinset coverage

Trowel notch Coverage per 50 lb bag
1/4 × 1/4 in square about 90 sq ft
1/4 × 3/8 in square about 60 to 80 sq ft
1/2 × 1/2 in square about 40 to 50 sq ft

Use the trowel size your tile and thinset makers specify for your tile.

For laminate, vinyl plank or wood floors, the flooring calculator uses the flooring makers’ cutting allowances and counts boxes and underlayment.

For the installed price of a tile floor, use the tile installation cost calculator.

Questions and answers

How much extra tile should I buy?

About 10% for a straight or offset layout and 15% for a diagonal one (Clé Tile), and around 20% for herringbone or chevron patterns (Fireclay Tile). Keep a few spare tiles: matching them years later is hard.

How many 12 × 12 tiles do I need for 100 square feet?

108 tiles. Each 12 in tile with a 1/8 in joint covers about 1.02 square feet, and 100 square feet plus 10% extra is 110 square feet.

How much grout do I need?

It depends on the tile size, the joint width and the tile thickness. With 12 × 12 in tiles 3/8 in thick and 1/8 in joints, a 25 lb bag of MAPEI Keracolor S covers about 383 square feet. Small tiles and wide joints need much more grout, which is why the calculator uses MAPEI's formula.

How much thinset do I need?

A 50 lb bag of thinset covers about 90 sq ft with a 1/4 × 1/4 in square-notch trowel, about 60 to 80 sq ft with a 1/4 × 3/8 in trowel, and about 40 to 50 sq ft with a 1/2 × 1/2 in trowel (Custom Building Products, MAPEI). The calculator uses the low end of each range.

How much does tile installation cost?

Labor typically costs $3 to $15 per square foot (Angi, HomeAdvisor, This Old House), depending on the tile size, the pattern and the prep the floor needs. Angi puts the tile itself at roughly $2 to $15 per square foot.

How much does it cost to tile a 10 × 10 bathroom floor?

Labor alone runs about $300 to $1,500 for 100 sq ft at $3 to $15 per square foot (Angi), plus the tile, grout and thinset. Removing an old floor, and large or patterned tile, push the price up.

How do I measure a room for tile?

Multiply the length by the width for a floor, or the width by the height for a wall. Split L-shaped rooms into rectangles and add them, and leave out the areas under cabinets and tubs.

Sources

Figures checked October 2026.