Square Footage Calculator

How to Measure Square Footage

Measuring square footage seems basic until you encounter a room that is not a perfect rectangle — which describes most real spaces. Closet nooks, bay windows, angled walls, and open floor plans all complicate what should be simple multiplication. The most reliable approach is to break any irregular space into rectangles, measure each one separately, and add them together.

For a standard rectangular room, measure the length and width at the widest points, wall to wall. Multiply length by width in feet to get square footage. A 12-foot by 14-foot bedroom is 168 square feet. For accuracy, measure in inches and convert to feet by dividing by 12, especially in older homes where walls may not be perfectly parallel — a room that appears 12 feet wide might actually be 11 feet 10 inches on one end and 12 feet 2 inches on the other.

Measuring Irregular Rooms

L-shaped rooms are the most common irregular shape in residential homes. Divide the L into two rectangles, measure each separately, and add them. An L-shaped living room might break into a 15 × 12 section (180 sq ft) and a 10 × 8 section (80 sq ft) for a total of 260 square feet. Sketch the room on paper with dimensions labeled before doing any math — it prevents the kind of errors that lead to ordering 30% too much flooring.

For rooms with angled walls (common in attics and some modern designs), treat the angle as a triangle. Measure the base and height of the triangular section, multiply, and divide by two. Add that to the rectangular portion. For curved walls like bay windows, approximate the curve as a half-circle using the depth and width of the bump-out.

What Counts as Square Footage in Real Estate

When buying or selling a home, square footage is money — literally. A 100 square foot discrepancy at $200 per square foot is a $20,000 pricing difference. The American National Standards Institute (ANSI) guidelines define livable square footage as finished space with at least 7-foot ceilings that is heated and accessible from the main living area. Garages, unfinished basements, attics without proper ceiling height, and screened porches are excluded from the official count.

This matters because listing agents sometimes include finished basements or enclosed porches in the total square footage, inflating the number to justify a higher price. If you are buying, ask specifically whether the quoted square footage follows ANSI standards. If you are selling, an appraiser will measure by ANSI rules regardless of what was in the listing, and a bank will lend based on the appraiser's number, not the listing.

Cost Estimates by Project Type

Flooring installation runs $3-12 per square foot for materials plus $2-6 for labor. Painting costs $1.50-3.50 per square foot of wall area (not floor area — walls have 2-3× more surface than the floor). Carpet is $2-8 installed. Hardwood is $6-18 installed. Tile is $5-15 installed. Knowing your exact square footage before getting quotes prevents contractors from padding the number, which is one of the most common ways estimates get inflated.

How do I calculate square footage?

For rectangles: length × width. For triangles: base × height ÷ 2. For circles: π × radius². For irregular shapes: break into simple shapes, calculate each, and add together. Always measure in feet for square footage results.

How many square feet in an acre?

43,560 square feet. A typical suburban lot of 0.25 acres is 10,890 square feet. A football field (without end zones) is about 48,000 square feet, slightly larger than one acre.

How do I convert square feet to square meters?

Divide by 10.764. So 1,500 square feet is about 139 square meters. Going the other direction, multiply square meters by 10.764 to get square feet.