Square Footage Calculator
Calculate the square footage of any room or space in multiple shapes.
The Formula
Triangle: A = ½ × b × h
Circle: A = π × r²
L-shape: divide into rectangles and sum
Section 1: 12 × 10 = 120 ft²
Section 2: 8 × 6 = 48 ft²
Total = 168 ft²
How to Calculate Square Footage
Square footage is simply the area of a two-dimensional space measured in square feet. For a rectangle or square room, multiply the length by the width. A 12 x 15 foot bedroom is 180 square feet. For a circular space, use pi times the radius squared (3.14159 x r x r). For a triangle, multiply the base by the height and divide by two. For irregular or L-shaped rooms, divide the space into simple rectangles, calculate each, and add the totals together. Always measure at the longest points of each wall for the most accurate results.
Common Uses for Square Footage Calculations
Knowing a room's square footage helps with almost every home improvement project: buying the right amount of flooring, paint, tile, or carpet; understanding your heating and cooling capacity needs; comparing rental or home prices; calculating property taxes; planning furniture layouts; and estimating renovation costs. Contractors price almost everything — painting, flooring, HVAC, cleaning — by the square foot.
Tips for Accurate Measurements
Use a quality tape measure and measure walls at floor level where the room is widest. For rooms with alcoves, closets, or bump-outs, measure each section separately and add or subtract as appropriate. Measure in feet and decimal fractions of feet rather than feet and inches — it makes multiplication much easier. A digital measuring tool (laser measure) makes large space measurements faster and more accurate than a tape measure.
Frequently Asked Questions
How do real estate agents measure square footage?
In most US markets, only finished, livable, above-grade interior space is counted in the advertised square footage. This typically excludes garages, unfinished basements, attics, and enclosed porches — even if they are heated. Finished basements are sometimes counted separately. Methods and standards vary significantly by region and MLS, which is why square footage figures in listings can be inconsistent.
How many square feet is a typical house?
The average new US single-family home is approximately 2,300 square feet. A small starter home or older ranch typically runs 900–1,400 square feet. A comfortable 3-bedroom home is often 1,400–2,000 square feet. Homes over 3,000 square feet are considered large by most standards. Square footage needs vary enormously by family size, lifestyle, and budget.
How do I convert square feet to square meters?
Multiply square feet by 0.0929 to get square meters. Or divide by 10.764. For example, 500 square feet equals about 46.5 square meters. Going the other direction, multiply square meters by 10.764 to get square feet.
How do I calculate square footage for flooring in an oddly shaped room?
Divide the room into simple rectangles. Measure each rectangle separately, calculate its area, and add all areas together. For closets, measure and add them separately. For curved walls or rounded corners, treat them as the nearest rectangle and the extra material purchased in your waste factor will cover the difference.
How much does a square foot of living space cost?
The cost per square foot for new construction in the US typically ranges from $100–$200+ per square foot for the structure alone, depending heavily on location, materials, and finishes. Custom homes in expensive markets can run $300–$500+ per square foot. Renovation costs vary widely by project type — kitchen and bathroom remodels average $100–$300 per square foot, while simple cosmetic updates run much less.