Square Footage Calculator
Free square footage and home measurement calculators -- real square feet, materials, and costs for flooring, paint, carpet, fencing, decking, and more.
Total area
120.0 sq ft
In square meters
11.1 sq m
Total cost
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How to calculate square feet
Square footage is just area -- length times width, using whichever formula matches the shape you're measuring. Measure in feet (or feet and inches, then convert the inches to a decimal), plug the numbers into the matching formula below, and round up slightly if you're buying material rather than just reporting a number.
| Shape | Formula | Worked example |
|---|---|---|
| Rectangle / square | length x width | 12 ft x 10 ft = 120 sq ft |
| Triangle | 0.5 x base x height | 0.5 x 8 ft x 6 ft = 24 sq ft |
| Circle | pi x radius^2 | pi x (5 ft)^2 = ~78.5 sq ft |
| Trapezoid | 0.5 x (base1 + base2) x height | 0.5 x (10 + 6) ft x 4 ft = 32 sq ft |
| L-shape | rectangle A + rectangle B | split into two rectangles, add the areas |
Measuring a room with a sloped ceiling, like an attic or a room under a roofline? Roof geometry itself -- rise, run, and pitch -- isn't something a flat-floor square-footage calculator handles; FrameSums' roof pitch calculator covers that piece separately. And once you know a room's square footage, two adjacent trades this site doesn't cover live on a sibling site: StoneCalc's shingle calculator for roofing squares, and its tile calculator for bathroom or kitchen tile counts.
Measurement Calculators
Step-by-step square footage formulas for rectangles, L-shapes, circles, and triangles, with unit conversions and an interactive multi-shape calculator.
Flooring CalculatorTurn a room's square footage into boxes of flooring, with the right waste percentage for a straight or diagonal layout, plus total material cost.
Carpet CalculatorCalculate linear feet, square yards, seams, and padding for a carpet job from 12 ft or 15 ft roll widths, plus material and installation cost.
Paint CalculatorCalculate gallons of paint from wall area, minus standard door and window openings, with coats, a ceiling option, and a primer coat.
Drywall CalculatorCalculate drywall sheets, screws, joint tape, and joint compound from square footage, in 4x8, 4x10, or 4x12 sheet sizes.
Fence CalculatorCalculate posts, rails, pickets, gates, and concrete bags for a fence from linear feet, post spacing, picket width, and gap.
Deck CalculatorCalculate deck boards, joists, and screws from deck dimensions, board width, board gap, and 12 in or 16 in joist spacing.
Wallpaper CalculatorCalculate wallpaper rolls from wall area and pattern repeat, using real usable roll coverage instead of a roll's nominal size.
Baseboard CalculatorCalculate linear feet of baseboard trim from a room's perimeter and openings, plus the pieces needed from a given stock length.
Acreage CalculatorConvert between square feet, acres, square meters, and hectares, with a lookup table of common residential and rural lot sizes.
Square Feet to Square Meters ConverterConvert square feet to square meters and back, with a reference table of common area sizes shown in both units side by side.
Roof Square Footage CalculatorCalculate roof surface area, roofing squares, and shingle bundles from your roof's footprint and pitch, with a waste allowance.
Frequently Asked Questions
How do I calculate square footage for an odd-shaped room?
Split the room into simple shapes -- rectangles, a triangle, a trapezoid, a circle -- that together cover the whole floor, find each one's area, and add them up. The calculator above does exactly this: add one shape per section of the room (an L-shaped room is just two rectangles) and it totals them for you.
What's the difference between square footage and square meters?
They're the same underlying area measured in two different unit systems -- 1 square meter equals about 10.76 square feet. The calculator above shows both at once, so you don't need a separate conversion step.
How do I subtract a closet, island, or fixed fixture from a room's area?
Toggle "Subtract a cut-out" on that room's card and enter the cut-out's own length and width -- it's treated as its own small rectangle and removed from the room's gross area before the total is calculated.
Do I need to account for wall thickness?
This calculator uses the dimensions you measure and enter, so if you measure wall-to-wall (interior finished dimensions) you'll get interior square footage; if you measure to the framing or exterior walls, you'll get a larger, structural square footage. Real estate listings almost always use interior finished square footage.
Can I use this for a whole house, not just one room?
Yes -- use "Add another room" for every room, hallway, and closet, and the running total adds them all together. For a single very large or irregular lot instead of a house, the acreage calculator below handles the bigger units (acres, hectares).