How to Calculate Tile Square Meters

Updated 11 November 2026 · Standard formula, shown below

This guide shows you how to measure a room or surface and calculate the exact square meters of tile you need to buy. You’ll learn the simple length × width formula, how to account for waste and cuts, and how to avoid common ordering mistakes. Before you start, grab a tape measure, a notepad, and a calculator.

What You’ll Need

Tape measure (laser measure works too)
Notepad and pen
Calculator
Pencil and paper for sketching the floor plan

Step-by-Step

Measure the length and width of the area. Using your tape measure, measure the longest side (length) and the shortest side (width) of the room. Measure in meters to the nearest centimeter (0.01 m). If the room is not a perfect rectangle, break it into smaller rectangular sections and measure each one separately.
Convert all measurements to meters. If your tape shows centimeters, divide by 100. For example, 3 m 45 cm = 3.45 m. If you measured in feet and inches, convert to meters by multiplying feet by 0.3048 and adding inches × 0.0254.
Calculate the area of each rectangle. Multiply the length by the width for each section. The formula is: Area (m²) = Length (m) × Width (m). Write down each result.
Add up all section areas. If you divided the room into multiple rectangles, sum the areas to get the total floor area in square meters.
Add waste allowance. Multiply the total area by 1.10 (for 10% extra) for a standard installation with straight lay. For diagonal layouts or rooms with many corners, multiply by 1.15 (15%). This extra covers cuts, breakage, and future repairs.
Round up to the nearest whole box. Check the coverage on the tile box (usually listed in square meters per box). Divide your total (including waste) by the box coverage, then round up to the next whole number. This is the number of boxes you need to order.

Common Mistakes

Mixing units. Using centimeters in one measurement and meters in another leads to wildly wrong areas. Always convert everything to meters before multiplying.
Forgetting to add waste. Without 10% extra, you may run short, especially if you make a cutting mistake or a tile breaks.
Ignoring non-rectangular shapes. Trying to measure an L-shaped room as one rectangle will overestimate the area. Break it into two rectangles and add them.
Not rounding up. If your calculation gives 12.3 boxes, you cannot buy 0.3 of a box. You must round up to 13.

Tips

Measure twice, order once. Double-check all measurements before you buy.
For walls, measure the height and width of each wall section, then multiply. Subtract areas for doors and windows only if they are large; for small windows, it’s often easier to keep the full area to cover waste.
If you are tiling a backsplash, measure the total area and add 10% for cuts around outlets and corners.
Keep the tile box’s coverage information handy. It is usually printed on the box or the product page.
If you are using large-format tiles (60×60 cm or larger), add a bit more waste (12-15%) because cutting them is less forgiving.

Troubleshooting

My area calculation seems too large. Re-measure the length and width. Check that you didn’t accidentally use the perimeter (adding all sides) instead of the area. Also, verify you converted all units to meters.
My area seems too small. Make sure you are measuring the full width, not just the visible floor. Also, if you have an irregular shape, you might have missed a section. Sketch the room and label each measurement.
I got a decimal number of boxes. Always round up. You cannot buy a fraction of a box, and having a few extra tiles is better than running out mid-project.
I have a diagonal layout and I’m not sure how much waste to add. Use 15% instead of 10%. Diagonal cuts create more waste because you have to cut tiles at angles.
My room has a closet or a bay window. Measure the closet floor separately if you plan to tile it. For a bay window, measure the floor area of the bay as a separate rectangle and add it to the main room area.

Frequently Asked Questions

Q: Do I need to subtract the area of doorways?
A: Generally, no. Doorways are small and the extra tile will be used for cuts elsewhere. For large openings (like a sliding glass door), you can subtract the width of the opening if you are not tiling that threshold.

Q: How much waste should I add for a simple rectangular room?
A: 10% is standard for a straight lay. If the room is perfectly rectangular and you are experienced, you might get away with 8%, but 10% is safer.

Q: What if my tiles are sold by the piece, not by the box?
A: Then divide the total area (including waste) by the area of one tile (in m²) and round up to the nearest whole tile. For example, a 60×60 cm tile is 0.36 m².

Q: Should I measure in feet and inches if my tape measure uses them?
A: You can, but you must convert to meters for the calculation. Multiply feet by 0.3048 to get meters. Or use a calculator that can handle feet and inches directly.

Q: Do I need to include the grout lines in my calculation?
A: No. Grout lines are usually a few millimeters wide and are negligible. The tile coverage on the box already accounts for the slight spacing.

Q: What if my room is a weird shape, like a circle?
A: For a circle, measure the diameter (distance across the center). The area is π × (diameter/2)². Add 15% waste because circular cuts are tricky.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.