Square Footage Calculator
Calculate the square footage of a room or area from its dimensions — rectangles, circles, triangles, and multi-room layouts.
Enter the shape and dimensions of your room. For an L-shaped or irregular room, split it into two or more rectangular sections using "Add another section" and this calculator will add them together.
Step-by-Step Solution
Here's exactly how this answer was calculated, one step at a time.
- 1
Calculate the rectangle area
12 × 10 ft = 120 sq ft
For a rectangle or square, area equals length times width.
✓ Final Answer: 120 square feet
Free Online Square Footage Calculator
This square footage calculator finds the area of a room, yard, or any flat space from its dimensions, then converts that number into square feet, square inches, square yards, square meters, and acres all at once. It handles rectangles and squares, circles, and triangles, and it lets you add multiple sections together — which is exactly what you need for an L-shaped room, a house with several rooms, or a yard made up of more than one distinct area.
Square footage is one of the most commonly needed numbers in home improvement, real estate, and construction — it drives flooring quotes, paint estimates, real estate listings, rental pricing, and material orders. Getting it right the first time saves a wasted trip back to the hardware store.
What Is Square Footage?
Square footage is a measurement of area — how much flat surface a space covers — expressed in square feet. One square foot is a square that measures 1 foot on each side. A room's square footage tells you how much flooring, carpet, paint (combined with wall height), or tile you'd need to cover it, and it's the standard way homes, apartments, and commercial spaces are sized and compared in the US.
Square Footage Formulas by Shape
The formula depends on the shape of the space you're measuring. This calculator supports three shapes covering the vast majority of real rooms and areas:
- Rectangle or Square:
Area = Length × Width - Circle:
Area = π × (Diameter ÷ 2)², or equivalently π × Radius² - Triangle:
Area = (Base × Height) ÷ 2 - Irregular / L-shaped rooms: split into two or more rectangles, calculate each one, and add the areas together
How to Use This Calculator
Choose the shape that matches your space, then enter its dimensions in whatever unit you measured — feet, inches, meters, centimeters, or yards. For a rectangle, that's length and width; for a circle, it's the diameter (the distance straight across, through the center); for a triangle, it's the base and the height. If your room isn't a simple rectangle — an L-shaped living room, a bump-out closet, or a house with several separate rooms to total up — click 'Add another section' and enter each part separately. The calculator adds every section together and shows the combined total instantly, in five different area units. Add a price per square foot to see an estimated material or project cost.
Worked Example: Simple Rectangle
A bedroom measures 12 feet by 10 feet. Area = 12 × 10 = 120 square feet. That's also equal to about 13.3 square yards, or 11.1 square meters — useful if you're comparing prices quoted in different units.
Worked Example: L-Shaped Room
An L-shaped living room can be split into two rectangles. Say the main section is 18 feet by 14 feet, and the smaller extension is 8 feet by 6 feet. Section 1: 18 × 14 = 252 square feet. Section 2: 8 × 6 = 48 square feet. Total: 252 + 48 = 300 square feet. Using the 'Add another section' feature in this calculator does exactly this automatically — no need to sketch it out by hand.
Worked Example: Circular Area
A round patio has a diameter of 14 feet. Radius = 14 ÷ 2 = 7 feet. Area = π × 7² = π × 49 ≈ 153.9 square feet. Circular spaces — patios, fire pits, round rugs, pools — all use this same formula.
Square Footage vs. Square Yards vs. Square Meters
Different trades quote in different units, so this calculator converts your total automatically. Flooring and carpet in the US are frequently priced by the square yard rather than the square foot — 1 square yard equals 9 square feet, so a 300 square foot room is about 33.3 square yards. Internationally, and in most scientific or metric contexts, area is measured in square meters — 1 square meter equals roughly 10.76 square feet. For very large areas like lots and land parcels, acres are standard — 1 acre equals 43,560 square feet.
How Square Footage Is Used
Knowing the exact square footage of a space matters across a wide range of situations:
- Real estate listings and home appraisals use total square footage as a core value driver.
- Flooring, carpet, and tile installers quote materials and labor based on square footage.
- Painters calculate wall area (combined with ceiling height) to estimate paint needed.
- HVAC contractors use square footage as a starting point for sizing heating and cooling systems.
- Landlords and property managers use it to set rent per square foot and compare units.
- Homeowners use it to plan furniture layouts, rugs, and renovation budgets.
Common Mistakes When Measuring Square Footage
A few errors show up again and again in DIY square footage measurements:
- Measuring wall-to-wall including closets and nooks when the intent was just open floor space, or vice versa — decide what should count before measuring.
- Mixing units within one room (measuring one wall in feet and another in inches) without converting first.
- Treating an L-shaped or irregular room as one single rectangle, which either overestimates or underestimates the true area.
- Using a circle's radius where the diameter was meant, or the reverse — double-check which one you actually measured.
- Forgetting to account for closets, alcoves, or bump-outs as separate small sections that still need to be added to the total.
Frequently Asked Questions
How do you calculate square footage of a room?
For a rectangular room, multiply the length by the width, both in feet: Square Footage = Length × Width. For non-rectangular rooms, split the space into rectangles (or other simple shapes), calculate each area separately, and add them together.
How do I calculate square footage for an L-shaped room?
Split the L-shape into two rectangles at the corner where the shape bends. Calculate the square footage of each rectangle separately, then add the two totals together for the overall square footage.
How many square feet are in an acre?
One acre equals 43,560 square feet. This calculator converts your total square footage into acres automatically, which is useful for larger yards, lots, or land parcels.
How do I calculate square footage from feet and inches?
Convert the inches portion into a decimal (inches ÷ 12) and add it to the feet, or simply select 'Inches' as the unit and enter the total length or width in inches — this calculator converts either way automatically.
How many square feet are in a square yard?
One square yard equals 9 square feet. This is a common conversion for flooring and carpet, which are often priced per square yard rather than per square foot.
How do I find the square footage of a circular area, like a patio or pool?
Measure the diameter (the distance straight across through the center), divide it by 2 to get the radius, then use Area = π × Radius². This calculator does that automatically when you select the circle shape and enter the diameter.
Does square footage include closets and hallways?
It depends on what you're measuring for. For a total livable area (common in real estate), closets and interior hallways are usually included. For a flooring or carpet estimate, you may want to measure only the specific area receiving new material — add each space you actually need covered as its own section.