A square footage calculator helps you measure the area of any room or space in square feet. Whether you are planning flooring, estimating paint, calculating rent per square foot, or measuring a property, getting the area right saves time and money. This tool handles rectangles, triangles, circles, trapezoids, and L-shaped rooms — and converts totals to square meters, acres, and square yards instantly.
Wall Area Calculator
Calculate total wall area (for painting, wallpaper, etc.) by entering room dimensions and subtracting openings.
How to Use the Square Footage Calculator
Knowing the square footage of a space is fundamental for flooring purchases, paint estimates, rental comparisons, and real estate valuation. This free square footage calculator handles five common shapes and lets you add multiple rooms to get a combined total.
Step 1: Choose Floor Area or Wall Area Mode
Use the toggle at the top to switch between Floor/Area mode (for floors, yards, plots) and Wall Area mode (for painting or wallpaper). Floor mode supports multiple rooms and irregular shapes; Wall mode is streamlined for a single room with openings subtracted.
Step 2: Select a Shape
Each section starts as a Rectangle. Use the shape dropdown to switch to Triangle, Circle, Trapezoid, or L-Shape. The input fields update to show exactly the dimensions required for each shape: base and height for a triangle, radius for a circle, both parallel sides and height for a trapezoid, and four measurements for an L-shape.
Step 3: Enter Dimensions
Type the measurements into the input fields. The default unit is feet — toggle to meters if you are working in metric. Conversions between sq ft, sq m, acres, and sq yards appear automatically. Formulas used: Rectangle = L × W, Triangle = ½ × base × height, Circle = π × r², Trapezoid = ½ × (a + b) × h, L-Shape = two rectangles summed.
Step 4: Add More Rooms
Click Add Another Section / Room to include additional spaces. Each section has its own shape and dimensions. The Total Area card at the bottom sums all sections and shows the grand total in square feet along with conversions to square meters, acres, and square yards.
Calculating Wall Area
Switch to Wall Area mode and enter the room length, width, and ceiling height. The tool calculates the gross wall area from the perimeter times height, then subtracts your doors and windows. Standard interior door area is about 20 sq ft (roughly 3 ft × 6.8 ft) and a typical window runs 12–15 sq ft. The net wall area is what you use for paint or wallpaper estimates.
Common Square Footage Conversions
1 square foot = 0.0929 square meters. 1 acre = 43,560 square feet. 1 square yard = 9 square feet. A typical US bedroom is 130–180 sq ft; a studio apartment averages 400–600 sq ft; a standard parking space is about 162 sq ft. These benchmarks help verify your measurements are in a sensible range before ordering materials.
Frequently Asked Questions
Is this square footage calculator free to use?
Yes, this square footage calculator is completely free with no signup required and no limits. All calculations run entirely in your browser — your measurements are never sent to any server and remain completely private on your device.
Is my data private when I use this tool?
Absolutely. Every calculation happens locally in your browser using JavaScript. No room dimensions or project details are ever transmitted to a server. Your information stays on your device.
How do I calculate the square footage of a room?
For a rectangular room, multiply the length by the width. A room that is 12 feet long and 10 feet wide has 120 square feet. For irregular shapes like L-shaped rooms, split them into two rectangles, calculate each area separately, and add the results together — exactly what this calculator does automatically.
How do I calculate square footage for an L-shaped room?
Select the L-shape option and enter the two lengths and two widths that make up the L. The calculator splits the L into two rectangles, computes each area, and adds them together. You can also add both rectangles as separate sections and let the Total row sum them.
How do I convert square feet to square meters?
Divide square feet by 10.7639. One square meter equals approximately 10.7639 square feet, so a 500 sq ft room equals about 46.45 square meters. This calculator shows the conversion automatically beneath the total area.
How do I calculate wall area for painting or wallpaper?
Switch to Wall Area mode at the top. Enter the room's perimeter (or length and width so the calculator computes perimeter for you), ceiling height, and the number and size of windows and doors to subtract. The result is the paintable wall area in square feet.
Can I add multiple rooms together?
Yes. Use the Add Section button to add as many rooms or spaces as you need. Each section has its own shape selector and dimension inputs. The Total row at the bottom sums all sections automatically, giving you the combined square footage.
What shapes can this calculator handle?
The calculator supports five shapes: Rectangle (length × width), Triangle (½ × base × height), Circle (π × radius²), Trapezoid (½ × (side A + side B) × height), and L-shape (two rectangles joined). Switch between them using the shape selector in each section.