Square Footage Calculator

How to Calculate Square Footage?

For rectangular areas, multiply the length by the width in feet. A room 15 feet long and 12 feet wide has 180 square feet. For circles, use pi x radius squared. A round patio 10 feet in diameter (5-foot radius) has 3.14 x 25 = 78.5 square feet. For triangles, use 1/2 x base x height. A triangular gable 20 feet wide and 6 feet tall has 60 square feet. The calculator above handles rectangles, circles, triangles, and trapezoids with input dimensions in feet, inches, meters, centimeters, or yards.

Why Is Square Footage Important in Construction?

Square footage is the foundation of nearly every construction estimate. Flooring, painting, roofing, siding, drywall, insulation, and tile are all purchased based on the area they must cover. Real estate is valued per square foot. Building permits and property taxes reference square footage. HVAC systems are sized proportionally to the conditioned square footage. Knowing how to accurately calculate area prevents over-ordering (wasting money), under-ordering (delaying the project), and budget miscalculations. It is the single most frequently used measurement in all of residential and commercial construction.

How to Measure Square Footage of a Room?

Use a tape measure to find the room length and width at the longest points. For rectangular rooms, multiply these two numbers. For L-shaped rooms, divide into two rectangles, calculate each separately, and add the results. For rooms with closets, measure the main room and the closet as separate rectangles and add together. For rooms with bay windows or bump-outs, add the protruding area as an additional rectangle. Record all measurements in feet and inches, converting inches to decimal feet (divide inches by 12) before multiplying. A room 12 feet 6 inches long is 12.5 feet.

How to Convert Between Area Units?

1 square foot = 144 square inches = 0.0929 square meters. 1 square yard = 9 square feet. 1 square meter = 10.764 square feet. 1 acre = 43,560 square feet. 1 hectare = 107,639 square feet = 2.471 acres. To convert Square Feet to Square Meters, multiply by 0.0929. To convert square meters to square feet, multiply by 10.764. These conversions appear frequently when working with international building specifications, importing materials listed in metric units, or comparing property sizes across countries that use different measurement systems.

How to Calculate Square Footage of a House?

Measure the exterior dimensions of each floor. For each floor, calculate the area of the main rectangle and add or subtract any bump-outs, bays, or insets. Add all floor areas together. Standard practice counts only finished, heated living space. Garages, unfinished basements, unfinished attics, porches, and balconies are typically excluded from the living square footage but may be listed separately in real estate listings. Measure to the outside of the exterior walls for consistency with appraisal standards. Interior-only measurements undercount by 5-10% because they miss the wall thickness.

Square Footage for Material Estimation

Different materials use square footage differently. Flooring: measure the floor area. Painting: measure the wall area (perimeter x height minus openings). Roofing: measure the roof area (footprint x pitch factor). Siding: measure the exterior wall area (perimeter x wall height minus openings). Drywall: measure wall area plus ceiling area. Insulation: measure the cavity area to be filled. Each calculation starts with square footage but applies different measurements (floor vs wall vs roof). Using the wrong area measurement for a material order is a common and costly mistake.

Price Per Square Foot: How to Compare Costs?

Divide the total cost by the total square footage. A $300,000 home of 2,000 square feet costs $150 per square foot. A $5,000 flooring job covering 500 square feet costs $10 per square foot. Price per square foot allows apples-to-apples comparison between different products, contractors, and properties. When comparing contractor bids, confirm they measured the same area. One contractor measuring 500 square feet and another measuring 550 for the same project will produce different per-square-foot prices even if their total prices are identical.

Common Square Footage Reference Points

A single car garage: 200-250 sq ft. A two-car garage: 400-500 sq ft. A standard bedroom: 120-150 sq ft. A master bedroom: 200-350 sq ft. A small bathroom: 35-50 sq ft. A full bathroom: 50-100 sq ft. A kitchen: 100-200 sq ft. A studio apartment: 300-500 sq ft. A two-bedroom apartment: 700-1,000 sq ft. An average US single-family home: 2,000-2,500 sq ft. A basketball court: 4,700 sq ft. A football field: 57,600 sq ft (including end zones). These benchmarks help visualize sizes when planning projects and evaluating property dimensions.

Frequently asked questions