Room Area Calculator

Measuring a Rectangular Room

Measure length and width at the widest points of the room, including any alcoves or bump-outs that will receive the same flooring or paint. Measure to the wall surface — not the baseboard face — for the most accurate area. For paint calculations, you'll also need the wall height (floor to ceiling) to calculate total wall area. Take measurements twice: measurement errors compound when calculating square footage and result in either short-ordering materials (requiring a second trip and possible lot-matching issues) or over-ordering with excess waste. For any measurement under 1 foot, record the fraction — don't round down.

L-Shaped and Irregular Rooms

Irregular rooms are easiest to handle by dividing them into rectangles. For an L-shaped room, mentally or physically divide it into two rectangles at the point where it changes shape, calculate each rectangle separately, then add them together. For a room with a diagonal wall, you can approximate it as a triangle (½ × base × height) and add that to the rectangular portion. Rooms with bay windows, angled corners, or recessed areas can be broken down the same way. For complex rooms, measure each distinct rectangular section, calculate its area, and sum them — it's more accurate than trying to find a single bounding rectangle and subtracting.

Including or Excluding Closets and Hallways

Whether to include closets depends on the project. For flooring, always include closets in square footage — they need flooring too. For paint, include closet walls if you're painting inside. For carpet estimates, measure the closet separately since carpet pattern direction may differ. For HVAC calculations (heat loss, square footage for equipment sizing), include all conditioned space including closets. For real estate listings, GLA (Gross Living Area) typically excludes unfinished spaces, garages, and sometimes closets depending on local convention. Measure what you're actually treating, not just the nominal room dimensions.

Converting Between Units

Square footage and square meters are the two most common units for residential measurements. 1 square meter = 10.764 square feet; a 200 sq ft room is approximately 18.6 m². Square yards are used primarily for carpet pricing in the US — divide square feet by 9 to get square yards. Tile and some flooring materials are sold by the box with coverage stated in square feet or metres, so matching units avoids errors. When in doubt about coverage, always refer to the manufacturer's specification on the product packaging — actual coverage varies by size, thickness, and installation pattern.