Square Footage Calculator
Calculate square footage for any room, shape, or project in seconds. Type your measurements and watch the area — and the diagram — update live.
- 100 % gratuit — sans inscription
- Résultats instantanés en temps réel
- Vos données restent dans votre navigateur
- Utilisée par les propriétaires et les artisans
Surface totale
Mètres carrés
180 m²
Yards carrés
215.3 yd²
Last updated: July 2026
What a square footage calculator does
A square footage calculator — also called an SF calculator or square footage estimator — measures the area of a space in square feet by multiplying its dimensions. To calculate square footage, you multiply length by width in feet (length × width = square feet). It replaces manual math and unit conversions so you get an accurate figure instantly — whether you are planning flooring, quoting a roofing job, or estimating paint.
Homeowners use it to plan renovations, contractors use it to price materials for flooring, roofing, concrete, drywall, and siding, and real-estate agents use it to measure the square footage of a house for listings. Because every calculation runs in your browser, it is free, instant, and completely private.
How to calculate square footage
To calculate square footage, measure the length and width of your space in feet and multiply them together. The formula is length × width = square feet. For example, a room that is 12 feet long and 15 feet wide is 12 × 15 = 180 square feet. Measuring in feet and inches? Convert the inches to a decimal first by dividing by 12 — so 10 ft 6 in becomes 10.5 ft.
Not every space is a simple rectangle. To measure an L-shaped or irregular room, divide the floor into rectangles, calculate each one, and add the results. For triangular areas use ½ × base × height, and for round areas use π × radius².
Square footage of a house
Measure each room's length × width, then add the rooms together. Finished living area usually excludes garages and unfinished basements.
Open the room calculatorFloor & flooring square footage
Use the floor area (length × width) and add a 5–10% waste factor for cuts when ordering tile, hardwood, laminate, or carpet.
Open the flooring calculatorWall square footage
Multiply wall width × height, then subtract about 21 sq ft per door and 15 sq ft per window to get the paintable area.
Open the wall calculatorSquare footage unit conversions
Square feet is standard in the US, but you may need metric units for imported materials or land area. Use these conversions — the calculator above shows sq ft, sq m, and sq yd side by side automatically.
| From | To | Multiply by |
|---|---|---|
| Square feet (sq ft) | Square meters (sq m) | 0.0929 |
| Square feet (sq ft) | Square yards (sq yd) | ÷ 9 |
| Square meters (sq m) | Square feet (sq ft) | 10.764 |
| Square yards (sq yd) | Square feet (sq ft) | 9 |
| Acres | Square feet (sq ft) | 43,560 |
Built to be accurate, fast, and effortless
Accurate for any shape
Rectangles, triangles, and circles — plus multi-section rooms — with the exact geometric formulas.
Instant, real-time results
No submit button. Square feet, meters, and yards update the moment you type a measurement.
Built for on-site use
Fast and mobile-friendly, so contractors and DIYers can measure right from a phone on the job.
Free unit conversion
Every result converts automatically between sq ft, sq m, and sq yd for any project or region.
Measure any space in four steps
From tape measure to total area — here's the exact process the calculator follows.
Measure the length
Use a tape measure to record the longest side of your space in feet (and inches if needed).
Measure the width
Measure the perpendicular side. For circles, measure the radius; for triangles, the base and height.
Pick the shape
Select rectangle, triangle, or circle so the calculator applies the correct area formula.
Read your result
Your square footage appears instantly, with square meters and square yards alongside it.
The exact formulas we use
Square footage is area measured in feet. To calculate it, multiply length by width. For other shapes we apply the standard geometric formula and round results to two decimals.
- Rectangle / room
- length × width = square feet
- Triangle
- ½ × base × height = square feet
- Circle
- π × radius² = square feet
- Irregular room
- split into rectangles, add each area
All square footage calculators
Ten specialized tools for every room, shape, and project.
Privé et sécurisé par conception
Calculé dans votre navigateur
Chaque mesure s'exécute côté client. Rien n'est téléversé, stocké ni envoyé à un serveur.
Aucune connexion, jamais
Aucun compte ni suivi des données de votre projet : ouvrez l'outil et mesurez.
Sécurisé par défaut
Entièrement servi en HTTPS sans contenu mixte, pour une connexion privée.
En savoir plus dans notre politique de confidentialité.
Square footage questions, answered
Quick, formula-backed answers to the most common measurement questions.
Pour calculer une surface en pieds carrés, multipliez la longueur par la largeur en pieds : longueur × largeur = pieds carrés. Pour une pièce de 12 × 15 ft, cela fait 12 × 15 = 180 ft². Pour les surfaces non rectangulaires, divisez l'espace en rectangles ou triangles, calculez chacun et additionnez.
Measure the length and width of the space in feet with a tape measure, then multiply the two: length × width = square feet. Measure to the inside of the walls at floor level for usable area. For rooms that aren't rectangular, split them into rectangles and add each area together.
Measure each room's length × width, then add the rooms together for the total. A house with a 12×15 living room (180 sq ft), two 10×12 bedrooms (240 sq ft), and a 8×10 kitchen (80 sq ft) is 500 sq ft. Finished living area usually excludes garages, unfinished basements, and open-to-below space.
Mesurez la longueur et la largeur de la pièce en pieds et multipliez-les : longueur × largeur = pieds carrés. Une chambre de 10 × 12 ft fait 120 ft². Pour les pièces en L, divisez le sol en rectangles, calculez chaque aire et additionnez.
Multiply the wall's width by its height: width × height = square feet. A 12 ft wide, 8 ft tall wall is 96 sq ft. For paint or wallpaper, subtract about 21 sq ft per door and 15 sq ft per window to get the paintable area you actually need to cover.
Convertissez les pouces en pieds en divisant par 12, puis multipliez longueur par largeur. Par exemple, 10 ft 6 in équivaut à 10,5 ft. Un espace de 10,5 × 12,25 ft fait environ 128,6 ft². Notre calculatrice a un champ dédié aux pouces.
A square footage calculator — also called an SF calculator or square footage estimator — is a free tool that works out the area of a space in square feet from your measurements. It applies the correct formula for each shape (length × width for rectangles) and converts instantly to square meters, square yards, and acres.
La superficie est une aire mesurée en pieds. Mesurez deux côtés perpendiculaires de l'espace en pieds et multipliez-les (longueur × largeur). Saisissez les valeurs dans la calculatrice ci-dessus : la surface s'actualise instantanément, mètres et yards carrés inclus.
Measure your space now
Free, instant, and private. Get accurate square footage for any room, shape, or project — no sign-up required.