Square Footage Calculator
Updated 2026-10-14
Enter the length and width of each rectangular part of the space. For a simple room, fill in the first row only. For an L-shaped room, use two rows. The calculator adds them up and converts between square feet and square meters.
How to calculate square footage
Square footage is the area of a flat surface measured in square feet: the number of 1 × 1 ft squares that would fit on it. For a rectangle, multiply the length by the width. Most rooms are rectangles or can be split into rectangles, so this one formula covers almost every floor, wall or patio.
Total area = area 1 + area 2 + area 3
Square meters = square feet ÷ 10.764
Worked example
An L-shaped living room can be split into a main area of 12 × 10 ft and a dining nook of 8 × 6 ft. The main area is 120 sq ft and the nook is 48 sq ft, so the total is 168 sq ft. Divided by 10.764, that's 15.61 square meters.
How to measure a room
- Sketch the room on paper, including alcoves, closets and bay windows.
- Divide it into rectangles. Draw lines to split odd shapes into simple boxes that don't overlap.
- Measure each rectangle wall to wall at floor level. Round up to the nearest inch (or centimeter).
- Convert inches to feet by dividing by 12: 10 ft 6 in is 10.5 ft, and 10 ft 3 in is 10.25 ft.
- Enter each rectangle in its own row and read off the total.
Area formulas for other shapes
Not every space is made of rectangles. Work out these shapes separately, then enter the result in a spare row as "area × 1".
| Shape | Formula | Example |
|---|---|---|
| Rectangle or square | length × width | 12 × 10 ft = 120 sq ft |
| Right triangle | base × height ÷ 2 | 6 × 4 ft = 12 sq ft |
| Circle | 3.1416 × radius × radius | 10 ft across (radius 5) = 78.5 sq ft |
| Half circle (bay, arch) | 3.1416 × radius × radius ÷ 2 | radius 4 ft = 25.1 sq ft |
| Trapezoid | (side a + side b) ÷ 2 × height | (10 + 6) ÷ 2 × 5 ft = 40 sq ft |
Square feet and square meters
One square meter equals about 10.764 square feet, and one square foot equals about 0.0929 square meters. A quick mental check: divide square feet by 10 for a rough square-meter figure, then knock off a little. So a 200 sq ft room is just under 20 m² (18.6 m² to be exact).
What square footage is used for
Area is the starting point for most material estimates. Flooring, tile, carpet, underlayment and floor paint are all sold by area. Wall area (for paint, wallpaper or drywall) works the same way, using wall length × wall height. For home sales and rentals, the "square footage" of a house usually means the finished, heated living space, measured to local rules that differ between countries and regions, so check how your listing or appraisal defines it.
Don't forget waste
The area this calculator gives is the exact size of the space. When you buy materials, add a waste allowance for cuts and mistakes: around 10% for flooring and straight-laid tile, and 15% or more for diagonal or patterned layouts. Our flooring and tile calculators add the waste for you and round up to whole boxes.
Frequently asked questions
- How many square feet is a 12 × 12 room?
- 144 sq ft, which is about 13.4 square meters.
- How do I calculate square footage in inches?
- Multiply length by width in inches, then divide by 144. A 48 × 30 inch area is 1,440 square inches, or 10 sq ft.
- Do I include closets when measuring for flooring?
- Yes, if the new flooring will go into the closet. Measure it as a separate rectangle and add it in a spare row.