How do I calculate square footage for tile?

Measure the length and width of the area in feet, then multiply them: length × width = square feet. For a room made of several rectangles, calculate each one and add them together. For walls or a backsplash, use height × width and subtract any doors, windows, or fixtures.

How many square feet is a 10x10 room?

A 10 ft by 10 ft room is 100 square feet (10 × 10 = 100). With the standard 10% waste allowance you'd buy tile for about 110 square feet.

How do I convert inches to feet when measuring?

Divide the inches by 12. For example, 8 feet 6 inches is 8 + (6 ÷ 12) = 8.5 feet. Do this for both the length and width before multiplying, or use our calculator, which accepts feet and inches directly.

Should I add waste to my square footage?

Calculate the true square footage first, then add 10% for straight layouts or 15% for diagonal and herringbone patterns. Keeping the two steps separate makes it easy to see your actual area and adjust the waste percentage for your tile and pattern.

How do I measure square footage for a backsplash?

Measure the width of the counter and the height from countertop to the bottom of the upper cabinets, multiply them for each wall section, and add the sections together. Subtract large gaps like windows, but leave small outlet cutouts in — they help cover waste.

How to Calculate Square Footage for Tile (Step by Step)

Quick answer: Measure length and width in feet and multiply them — length × width = square feet. For an irregular room, split it into rectangles, find each area, and add them up. For walls or a backsplash, use height × width and subtract doors and windows. Then add 10–15% for waste before buying.

Square footage is the foundation of every tile estimate — get it right and the tile count, box count, and cost all fall into place. This guide walks through measuring floors and walls, handling odd shapes, and converting your square footage into tiles.

The formula

Square feet = length (ft) × width (ft)

If your measurements are in inches, divide by 12 first to convert to feet. For example, a wall that is 102 inches wide is 102 ÷ 12 = 8.5 feet.

Step 1: Measure the floor

Measure the longest length and the widest width of the room in feet, rounding up to the nearest inch. Multiply them together.

A bedroom 12 ft × 11 ft = 132 square feet.

Step 2: Handle L-shaped and irregular rooms

Don’t try to measure an odd shape in one go. Divide it into rectangles, calculate each one separately, then add the results.

L-shaped room: Rectangle A (10 ft × 8 ft = 80 sq ft) + Rectangle B (6 ft × 4 ft = 24 sq ft) = 104 square feet.

For a room with a diagonal wall, complete the rectangle and treat the leftover triangle as ½ × base × height, then subtract it. Curved areas are easiest to approximate with the smallest rectangle that contains them.

Step 3: Measure walls, showers, and backsplashes

Vertical surfaces use the same math — height × width — measured wall by wall:

Shower or bathroom walls: measure each wall separately, then add them. See how to calculate shower tile.
Backsplash: counter width × height from counter to cabinets. See how to calculate backsplash tile.
Full walls: subtract doors and windows over ~10 sq ft; leave small openings in as built-in waste coverage.

Common room sizes (quick reference)

Room dimensions	Square footage	+10% waste
5 × 8 ft	40 sq ft	44 sq ft
8 × 10 ft	80 sq ft	88 sq ft
10 × 10 ft	100 sq ft	110 sq ft
12 × 12 ft	144 sq ft	159 sq ft
15 × 20 ft	300 sq ft	330 sq ft

Step 4: Turn square footage into tiles

Once you have your square footage, divide by the area one tile covers to get the tile count, then add waste and round up to full boxes. A quick way is to multiply your square footage by the tiles-per-square-foot figure for your tile size. For the full method, see how many tiles do I need.

Common mistakes to avoid

Mixing units: convert every measurement to feet before multiplying.
Forgetting waste: square footage is the area — you still need 10–15% extra tile on top.
Measuring only once: walls are rarely perfectly square; measure both ends and use the larger number.
Over-deducting openings: subtracting every small cutout leaves you short once cuts and breakage are counted.

Frequently asked questions

How do I calculate square footage for tile?: Measure the length and width of the area in feet, then multiply them: length × width = square feet. For a room made of several rectangles, calculate each one and add them together. For walls or a backsplash, use height × width and subtract any doors, windows, or fixtures.
How many square feet is a 10x10 room?: A 10 ft by 10 ft room is 100 square feet (10 × 10 = 100). With the standard 10% waste allowance you'd buy tile for about 110 square feet.
How do I convert inches to feet when measuring?: Divide the inches by 12. For example, 8 feet 6 inches is 8 + (6 ÷ 12) = 8.5 feet. Do this for both the length and width before multiplying, or use our calculator, which accepts feet and inches directly.
Should I add waste to my square footage?: Calculate the true square footage first, then add 10% for straight layouts or 15% for diagonal and herringbone patterns. Keeping the two steps separate makes it easy to see your actual area and adjust the waste percentage for your tile and pattern.
How do I measure square footage for a backsplash?: Measure the width of the counter and the height from countertop to the bottom of the upper cabinets, multiply them for each wall section, and add the sections together. Subtract large gaps like windows, but leave small outlet cutouts in — they help cover waste.

Skip the arithmetic: enter your room dimensions in feet and inches into our free tile calculator and it returns your square footage, tile count, boxes, and waste in one step — and lets you add multiple areas for L-shaped rooms.