How Much Tile Do I Need? Square Feet, Boxes and Overage by Layout

How much tile you need is the floor or wall area in square feet, plus an overage allowance for cuts, divided by the square feet in one box, rounded up to a whole box. The calculation behind a tile calculator or tile estimator is this arithmetic. Overage is the extra tile ordered on top of the measured area to cover cut pieces, breakage and spares. This guide lays out the numbers so you can check a calculator, or skip it: the formulas, the overage allowance for each layout, and worked examples with real box sizes for a kitchen floor, a shower, a backsplash, mosaic sheets, trim pieces and a pallet-sized order.

In short, with the working allowances this guide uses: square feet times 1.10 for a straight layout, times 1.15 for a diagonal or a big format, and times 1.20 for herringbone, then divide by the box coverage printed on the product page and round up. Box coverage is the number that changes the answer most, and it runs from 6.21 square feet for a box of 3 by 6 subway tile to 39.52 square feet for a box of vinyl plank.

The tile calculator formula

Step	Formula	Example
Area in feet	length (ft) x width (ft)	12 ft x 15 ft = 180 sq ft
Area in inches	length (in) x width (in) / 144	120 in x 18 in / 144 = 15 sq ft
Add overage	area x (1 + allowance)	180 x 1.10 = 198 sq ft
Boxes	total / sq ft per box, rounded up	198 / 16 = 12.4, so 13 boxes
Tiles	boxes x pieces per box	13 x 8 = 104 tiles
Area of one tile	tile length (in) x tile width (in) / 144	12 x 24 / 144 = 2 sq ft per tile
Tiles per sq ft	144 / (tile length x tile width)	144 / (12 x 24) = 0.5 tiles per sq ft

An L-shaped room or a wall with a window is split into rectangles first, each one is worked out on its own, and the rectangles are added together. A tub, a cabinet run or a kitchen island that will not be tiled under is taken out of the total. For metric plans, one square meter is 10.764 square feet, so a 20 square meter floor is 215.3 square feet before overage. The box coverage figure on a product page already accounts for the tile's real size, which is a hair smaller than its name: 50 pieces of a 3 by 6 inch subway tile cover 6.21 square feet, not the 6.25 the name suggests.

Overage allowance by layout

Overage is the tile that goes into cut pieces at the edges, pieces that break in handling, and a few spares kept after the job. The allowance grows with the number of cuts, and the number of cuts depends on the layout and on how the tile size fits the room. The quantity calculator on our product pages has an option to add 15% for cuts and waste. This guide uses 15% for the layouts with more cuts and works with 10% and 20% on either side of it; these are the working allowances for the examples here, not a fixed rule, and the right figure for a room depends on its shape and the tile.

Layout	Allowance	Multiply area by	Why
Straight grid	10%	1.10	Cuts only along the walls
Offset or brick	10%	1.10	Row ends can start the next row
Diagonal	15%	1.15	Every edge piece is a triangle
Herringbone or chevron	20%	1.20	Angled cuts on all four sides
Large format, 24x48 and up	15%	1.15	One cut piece is a big share of a box
Mosaic sheets	10% to 15%	1.10 to 1.15	Sheets cut along rows of small pieces

This guide raises its allowance for a small room, where a larger share of the floor lies along the edges and is cut. When the room dimensions are an exact multiple of the tile size, there are fewer cut pieces and the allowance can be at the low end.

Example 1: a 12 by 15 foot kitchen floor

The floor is 180 square feet. With the same room tiled four ways, the box count shows how the layout and the tile size change the order.

Tile and layout	Area with overage	Box	Boxes	Ordered
Pietra Calacatta 12x24, offset	180 x 1.10 = 198 sq ft	16 sq ft, 8 tiles	13	208 sq ft, 104 tiles
Pietra Calacatta 12x24, herringbone	180 x 1.20 = 216 sq ft	16 sq ft, 8 tiles	14	224 sq ft, 112 tiles
Pietra Calacatta 24x24, diagonal	180 x 1.15 = 207 sq ft	16 sq ft, 4 tiles	13	208 sq ft, 52 tiles
Sande Cream 48x48, straight	180 x 1.15 = 207 sq ft	32 sq ft, 2 tiles	7	224 sq ft, 14 tiles

The diagonal 24x24 lands on 13 boxes with almost nothing to spare: 207 square feet needed against 208 ordered. When the result comes that close to a whole box, one more box leaves room for a damaged piece or a measuring difference. The 48x48 shows the other side of big tile: each box holds 32 square feet, so rounding up adds 17 square feet over the allowance.

Example 2: shower walls

A shower tile calculator does the same math for walls. Take a 60 by 32 inch alcove with three tiled walls, 8 feet high: a back wall 5 feet wide and two side walls 32 inches wide.

• Back wall: 5 ft x 8 ft = 40 sq ft
• Side walls: 2.67 ft x 8 ft = 21.33 sq ft each, 42.67 sq ft for both
• Total: 82.67 sq ft, and with 10% overage, 90.93 sq ft

In the Mist 3x6 glossy subway tile, listed for shower walls, a box holds 50 tiles, 6.21 square feet. 90.93 divided by 6.21 is 14.64, so the shower takes 15 boxes: 750 tiles and 93.15 square feet. A niche adds its back and its four returns to the wall total, and a window takes its own area out. Our large format shower tile guide has the same wall worked out in 12x24 and 24x48 tile, where the piece count drops to a few dozen.

Example 3: a kitchen backsplash

A backsplash tile calculator starts with the counter run in inches and the height between the counter and the upper cabinets. A 10 foot run of counter with an 18 inch backsplash is 120 x 18 / 144 = 15 square feet. With 10% overage that is 16.5 square feet, and in the same 3x6 subway at 6.21 square feet per box, 16.5 divided by 6.21 is 2.66, so three boxes, 18.63 square feet. A full-height wall behind a range is its own rectangle, added on top; window openings and the area behind a range hood that will not be tiled come off.

Example 4: mosaic sheets

Mosaics are sold by the sheet, and the sheet coverage, not the size of the small pieces, is the number to divide by. A 5 by 8 foot bathroom floor is 40 square feet, and with 15% overage, 46 square feet. The Pietra Calacatta 2x2 mosaic covers 0.97 square feet per sheet with 8 sheets in a box, 7.76 square feet. 46 divided by 7.76 is 5.93, so 6 boxes: 48 sheets and 46.56 square feet. The same floor in a 12x12 hexagon marble mosaic at 0.984 square feet per sheet and 5 sheets per box comes to 47 sheets, so 10 boxes and 50 sheets.

Example 5: trim by the linear foot

Bullnose, pencil liners and other trim are counted by length, not by area, and the three trims below are each sold by the piece or by a box of pieces. The math is the total run in feet, plus 10%, divided by the length of one piece.

Trim	Piece length	45 ft run + 10% = 49.5 ft
Pietra Calacatta bullnose 3x18	18 in (1.5 ft)	33 pieces
Dimensions Concrete bullnose 3x24	24 in (2 ft)	25 pieces
Sapphire Blue glass pencil liner 0.5x12	12 in (1 ft)	50 pieces, 5 boxes of 10

The 45 foot run is the 12 by 15 foot kitchen above: 54 feet of wall, less a 3 foot door and a 6 foot opening to the next room. Bullnose that matches the field tile comes from the same series, so the trim and the floor share a color and a finish; trim shapes for every material are in our moldings.

Vinyl plank: the same math, bigger boxes

Luxury vinyl plank is counted the same way, with a much larger box. The 180 square foot kitchen with 10% overage needs 198 square feet. Katavia Bleached Elm 6x48 holds 36 square feet in a box, so 5.5 boxes rounds up to 6, or 216 square feet. Wilmont Charcoal Oak 7x48 holds 39.52 square feet, and here rounding matters: 5 boxes give 197.6 square feet, 0.4 short of the 198 needed, so the order is 6 boxes. Our luxury vinyl plank lists the box coverage on every plank.

Pallet orders for a whole job

On a large job the box count turns into pallets and pounds. MSI lists coverage per pallet and weight per piece for its porcelain, so the table below turns a box count into full pallets and total weight.

Tile	Per box	Per pallet	Weight per piece
Pietra Calacatta 12x24	16 sq ft, 8 tiles	512 sq ft, 32 boxes	8.05 lb
Brighton Crema 12x24	16 sq ft, 8 tiles	704 sq ft, 44 boxes	7.8 lb
Pietra Calacatta 24x24	16 sq ft, 4 tiles	480 sq ft, 30 boxes	16.35 lb
Sande Cream 48x48	32 sq ft, 2 tiles	736 sq ft, 23 boxes	73 lb

A 2,000 square foot floor in Pietra Calacatta 12x24 with 10% overage needs 2,200 square feet: 137.5 boxes, so 138 boxes and 2,208 square feet. That is four full pallets of 32 boxes plus 10 boxes, and at 8 tiles of 8.05 pounds per box, about 8,900 pounds of tile before packaging. Each production run of a tile can differ in shade, and buying the full quantity in one order keeps it to one run; our guide to ordering tile for a job explains lots, shade ratings and caliber, and the porcelain in large volume porcelain tiles is gathered for jobs that need a lot of one tile.

Quick reference: square feet to boxes

Area with overage	6.21 sq ft box (3x6)	16 sq ft box (12x24, 24x24)	32 sq ft box (48x48)	36 sq ft box (vinyl)
25 sq ft	5	2	1	1
50 sq ft	9	4	2	2
100 sq ft	17	7	4	3
250 sq ft	41	16	8	7
500 sq ft	81	32	16	14

The left column already includes overage. For a box size not in the table, the product page lists the square feet per box, and the same division applies.

Ordering for clients

Contractors, designers and builders who order tile for several jobs can apply to the Pros Club, our trade program. It is free to apply, trade pricing is applied automatically at checkout when you are logged in, and a dedicated trade specialist helps with selection, quotes and project support, including quantities for a job like the ones above. Our trade program guide explains how it works, and the large format tile guide lists the biggest formats with their box and pallet sizes.

Tile Calculator FAQ

Why does a 24x24 box cover the same area as a 12x24 box?

Both Pietra Calacatta boxes list 16 square feet, so the box count for a room is the same. What changes is the cutting: a 24x24 tile cut at a wall leaves a larger offcut than a 12x24, so in a small room the bigger tile can use more of the overage.

How many tiles are in a square foot?

144 divided by the tile's length times its width, in inches. A 4x4 tile gives 9 per square foot, a 6x6 gives 4, a 12x12 gives 1 and a 12x24 gives 0.5. Listed box coverage uses the tile's actual size, so the real count can come out slightly higher than the nominal one.

Does a tile calculator include waste?

Only if it is asked to. The quantity calculator on our product pages has a checkbox that adds 15% for cuts and waste; left unticked, it divides the area you enter by the box coverage and rounds up.

How much extra tile should I keep after the job?

One unopened box holds several replacement tiles: a box of Pietra Calacatta 12x24 holds 8 tiles, and a box of Sande 48x48 holds 2. Unopened boxes keep the carton label with the lot code, which helps match a later purchase.

Do I need the same overage for vinyl plank?

This guide uses 10% for a straight vinyl layout, the same as tile. Planks cut at a wall can start the next row, the same as an offset tile layout, which keeps vinyl at the low end of the range.