Carpet Tile Calculator

Carpet tile calculator: area ÷ 4, rounded up

This carpet tile calculator counts how many 24 × 24 inch tiles cover a room. The formula is tiles = (length × width) ÷ 4, rounded up, because each 2 × 2 ft tile covers 4 square feet. Tick the 10% option to allow for wall cuts and spares; that multiplies the count by 1.10 before rounding. Cost is the whole-tile count times your price per tile.

What happens inside the formula

Multiply the room’s length and width in feet to get square feet. Divide by 4. A 15 × 12 ft room is 180 sq ft, which is exactly 45 tiles. Rooms rarely come out that neatly, so the calculator always rounds the result up.

The waste step comes before the rounding. If the area already divides evenly, as in the default room, the 10% adds a full five tiles. If it does not, the extra may only add two or three.

Worked examples

1. Default room: 15 × 12 ft, $9 per tile

• Area: 15 × 12 = 180 sq ft
• Tiles: 180 ÷ 4 = 45 tiles, costing $405.00
• With 10%: 45 × 1.10 = 49.5, rounded up to 50 tiles, costing $450.00

2. Home office: 11 × 10.5 ft, $9 per tile, 10% on

• Area: 11 × 10.5 = 115.5 sq ft
• Net tiles: 115.5 ÷ 4 = 28.9, which would round to 29
• With 10%: 28.875 × 1.10 = 31.8, rounded up to 32 tiles, costing $288.00

Carpet tiles are usually sold by the box. If a box holds a fixed number, round up to whole boxes after you have the tile count.

Tile size and count reference

Tile size	Coverage per tile	Tiles per 100 sq ft
24 × 24 in	4.00 sq ft	25
50 × 50 cm (19.7 in)	about 2.69 sq ft	38
18 × 18 in	2.25 sq ft	45
9 × 36 in plank	2.25 sq ft	45
12 × 36 in plank	3.00 sq ft	34

Room (24 × 24 in tiles)	Area	Tiles, no waste	Tiles, 10% on
10 × 10 ft	100 sq ft	25	28
12 × 12 ft	144 sq ft	36	40
15 × 12 ft	180 sq ft	45	50
20 × 15 ft	300 sq ft	75	83

This calculator is set for 24 × 24 in tiles. For other sizes, use the coverage column and divide by hand.

How to measure a room for carpet tile

• Measure wall to wall at floor level. Baseboards hide a little floor, but tiles tuck under them, so measure to the wall.
• Add closets and alcoves. Measure each as its own rectangle and add the tile counts.
• Square up odd rooms. An L-shaped room is two rectangles. Do not fill in the missing corner.
• Plan the starting line. Tiles are laid from the room’s center outward so the cut tiles at opposite walls match.

Planning the layout before you order

Find the center of the room by snapping chalk lines between the midpoints of opposite walls. Dry-lay a row of tiles along each line to see how big the cut tiles at the walls will be. If a row ends in a sliver less than a few inches wide, shift the starting line by half a tile so both walls get larger, sturdier cuts.

Cut pieces from one wall can sometimes be used on the opposite wall, which lowers real waste. That is more likely in large open rooms than in small rooms with closets. Doorways usually need a transition strip where the tile meets another floor.

Common carpet tile mistakes

• Mixing production lots. Two dye lots side by side can show a visible color change. Buy everything, plus spares, in one order.
• Ignoring arrow direction. Decide on monolithic or quarter-turn before laying the first tile.
• Laying over a rough subfloor. Tiles telegraph bumps and gaps. Fill and flatten first.
• No acclimation. Many makers ask you to leave boxes in the room for about a day before installing.
• Choosing tile for a damp basement without checking. Some backings tolerate moisture better than others. Read the product specs.

Related calculators

For a seamless roll product, compare against the carpet calculator. The flooring calculator handles plank and laminate boxes, and the flooring underlayment calculator covers pad under hard floors.