How many 12x12 tiles do I need for 100 square feet?

About 108. With a 1/8 inch grout joint each 12x12 tile covers about 1.02 square feet, so 100 square feet takes 98 tiles before waste. Adding 10% for cuts and breakage brings it to 108. With no allowance for grout it would be 110.

How much extra tile should I buy?

Add about 10% for a straight layout, 15% for a diagonal layout and 20% for herringbone. Add more for small rooms, rooms with many corners, and large-format tiles, where one bad cut wastes a big piece. Keep a few spare tiles from the same lot for future repairs.

Do grout lines change how many tiles I need?

Slightly. Each tile plus its share of the grout joint covers a little more than the tile alone, so you need a few fewer tiles. The effect is biggest with small tiles: for 3x6 subway tile with a 1/8 inch joint, the grout adds about 6% to each tile's coverage.

How do I calculate tile for a shower or backsplash?

Measure each wall's width and the height to be tiled, multiply, and add the walls together. Subtract windows and niches you won't tile, then add waste. For a backsplash, measure the length of counter to cover and the height from the counter to the cabinets, and subtract outlets only if they're large.

What size grout joint should I use?

Use what the tile manufacturer recommends. Rectified tiles, which are cut to precise sizes, can use narrow joints such as 1/16 inch. Tiles with more size variation, such as handmade or rustic tile, need wider joints so the lines stay straight. The grout bag also lists the joint widths it's made for.

Free calculator

Tile Calculator: How Many Tiles and Boxes

Free tile calculator: tiles and boxes for a floor or wall from the area, tile size and layout, with waste.

Length

Width

Tile size

Grout joint

Layout

Tiles per box (optional)

Printed on the box.

Result

Tiles to buy

91tiles

12 boxes of 8

Area: 168.0 sq ft
With 10% waste: 184.8 sq ft
Each tile with grout covers: 2.03 sq ft
Tiles in those boxes: 96

Each tile is counted with half a grout joint on every side, which is why tiles with wider joints need slightly fewer pieces. Buy from one lot and keep a few spares.

How it's calculated

Tiles = area × (1 + waste %) ÷ area of one tile including its grout joint, rounded up. A 14 × 12 ft floor is 168 sq ft; with 10% waste that's 184.8 sq ft. A 12 × 24 in tile with a 1/8 in joint covers 2.03 sq ft, so you need 91 tiles, or 12 boxes of 8.

How to use the tile calculator

Enter the room's length and width, or switch to Total area and type the square footage of floors or walls you've already added up. Pick the tile size (or enter a custom one in inches), the grout joint and the layout. If you know how many tiles come in a box, enter it to get boxes. The calculator counts each tile with its share of the grout joint, adds the waste allowance and rounds up.

Tiles per 100 square feet by size

With a 1/8 in grout joint. Multiply by your area ÷ 100 for a quick estimate.

Tile size	One tile (sq ft)	Tiles, no waste	Tiles with 10% waste
3" × 6" subway	0.125	753	828
4" × 4"	0.111	847	931
6" × 6"	0.25	384	423
6" × 24" plank	1.0	98	108
12" × 12"	1.0	98	108
12" × 24"	2.0	50	55
24" × 24"	4.0	25	28

Waste allowance by layout

Layout	Allow	Why
Straight grid	10%	Cuts along two walls, plus breakage.
Offset (brick or running bond)	10–15%	Cut pieces at both ends of every row.
Diagonal	15%	Triangular cuts along every wall.
Herringbone	20%	Angled cuts at every edge and more breakage.
Large format (24 in and up)	Add 5%	Each miscut or cracked tile is a big piece.

For long rectangular tiles laid in an offset pattern, many manufacturers recommend shifting each row by no more than one-third of the tile length instead of half, because long tiles can have a slight bow. That changes where cuts land, so check the layout before you order.

Walls, backsplashes and trim

Wall tile is the same math with height in place of width. A shower with two 5 ft walls and one 3 ft wall, tiled 8 ft high, is (5 + 5 + 3) × 8 = 104 sq ft, less any window or niche. Trim pieces such as bullnose, pencil liner or metal edging are bought by the linear foot, so measure every exposed edge separately.

Measuring a floor for tile

Measure wall to wall at the longest and widest points, and round up to the next inch.
Include the floor around the toilet and under a freestanding tub or appliances you'll move in later.
Leave out floor under fixed cabinets and islands, which usually sit on the subfloor.
Measure closets and alcoves as their own rectangles and add them in.
Buy all tile from one lot (shade or caliber) so color and size match, and keep a few spares for repairs.

Measuring several rooms

For a bathroom, laundry and entry, add each area and use Total area, or use the square footage calculator for odd shapes. With a floor plan, FloorFigures measures each room for you, free, with the floor area and perimeter you need for tile and trim.

Updated October 12, 2026 · FloorFigures

Questions

How many 12x12 tiles do I need for 100 square feet?: About 108. With a 1/8 inch grout joint each 12x12 tile covers about 1.02 square feet, so 100 square feet takes 98 tiles before waste. Adding 10% for cuts and breakage brings it to 108. With no allowance for grout it would be 110.
How much extra tile should I buy?: Add about 10% for a straight layout, 15% for a diagonal layout and 20% for herringbone. Add more for small rooms, rooms with many corners, and large-format tiles, where one bad cut wastes a big piece. Keep a few spare tiles from the same lot for future repairs.
Do grout lines change how many tiles I need?: Slightly. Each tile plus its share of the grout joint covers a little more than the tile alone, so you need a few fewer tiles. The effect is biggest with small tiles: for 3x6 subway tile with a 1/8 inch joint, the grout adds about 6% to each tile's coverage.
How do I calculate tile for a shower or backsplash?: Measure each wall's width and the height to be tiled, multiply, and add the walls together. Subtract windows and niches you won't tile, then add waste. For a backsplash, measure the length of counter to cover and the height from the counter to the cabinets, and subtract outlets only if they're large.
What size grout joint should I use?: Use what the tile manufacturer recommends. Rectified tiles, which are cut to precise sizes, can use narrow joints such as 1/16 inch. Tiles with more size variation, such as handmade or rustic tile, need wider joints so the lines stay straight. The grout bag also lists the joint widths it's made for.

Skip the typing. Measure the plan.

Open the floor plan in FloorFigures and every room is measured for you, with the same math per room. Try it free on a sample plan; nothing is uploaded.