How to Measure a Room for Flooring, Including Irregular Shapes

Updated October 7, 2026 · 4 min read · Flooring

Every flooring estimate starts with square footage, and every waste allowance is a percentage of it. An error in the measurement carries straight through to the order. The good news: even complicated rooms break down into rectangles, triangles and the occasional circle.

What you need

• A 25 ft tape measure (or a laser measure for large rooms)
• Graph paper or a notes app to sketch the room
• A second person to hold the tape on long runs, if possible

The ground rules

1. Sketch first. Draw the room’s outline, including closets, doorways and any bump-outs. Write each measurement on the sketch as you take it.
2. Measure wall to wall at floor level, ignoring baseboards. Flooring runs under or up to the baseboard, and the small expansion gap is covered by trim.
3. Round up each measurement to the next inch (or next 0.5 ft if you prefer working in decimals).
4. Include closets and any area that will get the same floor.
5. Measure into doorways. Flooring usually ends at the midpoint of the door jamb, under the closed door, where a transition strip sits. Add that small strip to the room it belongs to.
6. Measure walls at both ends. Rooms are rarely perfectly square. Use the longer measurement.

Converting to square feet

Inches to feet: divide by 12. A wall that measures 13 ft 7 in is 13 + 7/12 = 13.58 ft.

Area = length (ft) × width (ft)

Metric: measure in metres; area is in square metres. 1 m² = 10.764 ft²; 1 ft² = 0.0929 m².

Shapes and formulas

L-shaped and irregular rooms

There are two ways to handle an L-shaped room, and doing both is a good check.

Method 1: Split into rectangles. Draw a line that divides the L into two rectangles, find each area, and add.

Method 2: Big rectangle minus the notch. Measure the overall rectangle that contains the whole room, then subtract the missing corner.

Both should give the same answer. If they don’t, re-measure.

For a room with an angled wall, treat the angle as a triangle cut from (or added to) a rectangle. For a curved wall, approximate with a half circle or measure the curve as a series of short straight segments.

Worked example: an L-shaped living and dining room

The room fits inside a 24 × 20 ft rectangle, with a 10 × 8 ft corner taken up by the kitchen. There’s a 2 × 6 ft closet and a bay window that’s 8 ft wide at the wall, 4 ft wide at the glass, and 2 ft deep.

Main L-shape, method 1 (split): - Rectangle A: 24 × 12 ft = 288 ft² - Rectangle B: 14 × 8 ft = 112 ft² - Total: 400 ft²

Method 2 (subtract): 24 × 20 − 10 × 8 = 480 − 80 = 400 ft². The two methods agree.

Add-ons: - Closet: 2 × 6 = 12 ft² - Bay window: (8 + 4) ÷ 2 × 2 = 12 ft²

Total floor area: 424 ft² (about 39.4 m²)

Add waste. For a straight lay in this shape, 10% is a sensible allowance: 424 × 1.10 = 466.4 ft². With flooring at 22 ft² per box: 466.4 ÷ 22 = 21.2 → 22 boxes (484 ft²).

The waste percentage depends on the layout you choose. A diagonal or herringbone pattern in the same room needs more; see flooring waste factor by layout.

What to subtract (and what not to)

Subtract large, permanent features that won’t be floored: - Kitchen islands and built-in cabinets (if flooring will not run under them) - Fireplace hearths - Built-in bathtubs and showers

Don’t subtract small obstacles: - Toilets, pedestals, radiator legs, floor vents - Areas under freestanding furniture or appliances. Floor under them in case you move them later.

Whether flooring goes under kitchen cabinets depends on the product and installation method. Many floating floors are installed around fixed cabinets, not under them. Check the manufacturer’s instructions.

Stairs and multiple rooms

Stairs are estimated separately, usually by counting treads and risers, because they need stair nosing and specific trim. Don’t try to fold them into room square footage.

Multiple rooms with the same flooring: measure each room separately, add the areas, then apply waste once to the total. Including hallways and closets on the same sketch helps you plan where boards will run continuously and where you need transitions.

Common mistakes

• Measuring to the baseboard face rather than the wall. You lose the depth of the baseboard on every side.
• Forgetting closets and doorway strips. Small areas add up.
• Assuming the room is square. Measure both ends of each wall and use the larger figure.
• Mixing feet and inches. 12 ft 6 in is 12.5 ft, not 12.6 ft.
• Applying waste to each room and rounding each one up. Add room areas first, then apply waste and round once.
• Ordering exactly to the square foot. Boxes only come whole; you’ll always round up.

Turn your measurements into boxes

Enter your total area, waste percentage and box coverage into the flooring calculator. It returns the number of boxes to order and the total square footage you’ll receive.

FAQ

How do I calculate square footage for an irregular room?

Break it into rectangles, triangles and circles, calculate each area, and add them together. For an L-shape, you can also take the overall rectangle and subtract the missing corner.

Should I include closets when measuring for flooring?

Yes, if they’ll get the same flooring. Measure them separately and add them to the room total.

Do I measure to the wall or the baseboard?

To the wall. Flooring extends under or up to the baseboard line, with an expansion gap that the trim covers.

How many square feet is a 12 × 15 room in square metres?

12 × 15 ft = 180 ft², which is about 16.7 m² (3.66 × 4.57 m).