Square Footage Calculator for Rooms, Floors and Any Shape
Our square footage calculator finds the area of a room, a floor or a whole house from a few measurements. Use it as a square feet calculator for rectangles, circles, triangles and trapezoids, with results in square meters and square yards too. Add a waste allowance and a price to estimate materials and cost.
What Square Footage Means
Square footage is the area of a flat surface measured in square feet. One square foot is a square that measures 1 foot on each side, or 144 square inches. When a listing says a home has 1,850 square feet, it means the floors would fill 1,850 of those squares.
You need this number for many everyday jobs. Flooring, carpet, tile, paint, sod and roofing are all sold or priced by area. A square footage calculator turns a few tape readings into that number in seconds.
How to Use the Square Footage Calculator
- Choose the unit you measured in: feet, inches, yards, meters or centimeters.
- Pick a shape for the first area and type its measurements.
- Click "Add another area" for each extra room or section, and set a quantity for repeats.
- Enter a waste allowance and, if you like, a price per square foot, yard or meter.
The results show the total area in square feet, square meters, square yards, square inches and acres. You also get the amount of material to buy once waste is added and an estimated cost. The note under the results lists each area, so you can check every line of the math.
Square Footage Formulas
Every shape has its own formula, but they all come back to length times width. The square footage calculator applies the right one when you pick a shape. Here is what it does behind the scenes.
Rectangles and Squares
Multiply the length by the width. A room that is 12 feet by 15 feet has an area of 180 square feet. For a square, multiply the side by itself, so a 10 foot square is 100 square feet.
Circles
Find the radius by halving the diameter, square it and multiply by π. A round patio 10 feet across has a radius of 5 feet and an area of about 78.54 square feet. Measure straight through the center to get the true diameter, then enter it in the square feet calculator.
Triangles
Multiply the base by the height and divide by 2. A triangle with an 8 foot base and a 6 foot height covers 24 square feet. The height must be measured at a right angle to the base, not along the slanted side.
Trapezoids
Add the two parallel sides, divide by 2 and multiply by the height. A garden bed with parallel sides of 10 and 14 feet and a depth of 8 feet covers 96 square feet. This shape often shows up in angled rooms and bay windows.
How to Calculate Square Footage of a Room
Start by clearing the edges of the room so the tape can run wall to wall. Measure the longest wall and the wall next to it at floor level. Write both numbers down before you move on.
If the room is a simple rectangle, multiply the two lengths and you are done. A bedroom that measures 12 feet by 15 feet is 180 square feet. Our square feet calculator gives the same answer when you enter 12 and 15.
L Shaped and Irregular Rooms
Most odd rooms can be split into simple shapes. Draw a quick sketch and divide it into rectangles, triangles or half circles. Then measure each piece. Add the pieces together for the total.
An L shaped living room might split into a 20 by 12 foot rectangle and a 10 by 8 foot rectangle. That gives 240 plus 80, for a total of 320 square feet. In the square footage calculator, enter each part as its own area and the tool adds them for you.
If a shape repeats, use the quantity box in the square footage calculator instead of typing it twice. Two bedrooms of 12 by 12 feet become one area with a quantity of 2. Add a 360 square foot living room and a 168 square foot kitchen and the square feet calculator shows 816 square feet in total.
Feet, Inches and Metric Units
Tape measures in the US often read in feet and inches. In feet mode you can type 12'6" or 12 ft 6 in, and the square footage calculator reads it as 12.5 feet. A room of 12'6" by 10'3" works out to 128.13 square feet.
If you measured in meters, switch the unit and enter the numbers as they are. A room of 4 by 5 meters is 20 square meters, which the square feet calculator converts to 215.28 square feet. Converting square feet to square meters by hand means multiplying by 0.0929.
| Unit | Equal to |
| 1 square foot | 144 square inches |
| 1 square yard | 9 square feet |
| 1 square meter | 10.764 square feet |
| 1 acre | 43,560 square feet |
To go the other way and convert square feet to square meters, divide by 10.764. Our Unit Converter handles plain length conversions if you only need feet to meters. The square feet calculator handles the area side with no extra steps.
Square Footage for Common Projects
Flooring and Tile
Buy more flooring than the bare area, because cuts, mistakes and odd corners waste material. Most installers add 5% to 10% for straight layouts and about 15% for diagonal or patterned tile. The waste box in the square footage calculator adds this for you.
For a 180 square foot room with 10% waste, you need 198 square feet of material. Flooring is often sold in boxes that cover a set area, so divide by the box size and round up. Keep one spare box for future repairs.
Carpet
Carpet is often priced by the square yard rather than the square foot. Divide square feet by 9 to get square yards, or read it from the square feet calculator. With 10% waste, the same 180 square foot room needs 22 square yards, which costs $660 at $30 a square yard.
Paint and Walls
For a wall, multiply its width by its height instead of length by width. A 12 foot wall that is 8 feet tall has 96 square feet to cover. Subtract doors and windows, then check the paint can, since most gallons cover about 350 to 400 square feet per coat.
Square Footage of a House
For a home, add the finished, heated living space on each floor. Most listings leave out garages, unfinished basements and open porches. In the US, many appraisers follow the ANSI Z765 standard, which measures from the outside of exterior walls.
Your own room by room total will usually come out a little lower than the listed figure. Interior measurements leave out the walls themselves. Use the square footage calculator for planning, and rely on a licensed appraiser when a sale or loan depends on the number.
Estimating Cost
Enter a price in the square feet calculator and choose whether it is per square foot, square yard or square meter. The cost uses the area with waste included, so the estimate matches what you will buy. Labor is usually quoted per square foot as well, so you can run the numbers twice.
At $3.50 per square foot, flooring for the 180 square foot room with 10% waste comes to $693. Compare quotes on the same basis, because some include waste and some do not. This area calculator gives you a fixed number to check every quote against.
Common Measuring Mistakes
- Mixing units, such as feet for one wall and inches for the other.
- Measuring along baseboards that hide a curved or uneven wall.
- Forgetting closets, alcoves or the space under built in cabinets.
- Measuring the slanted side of a triangle instead of its height.
Double check each number, because one wrong digit can turn 15 feet into 51. A quick sketch with every measurement on it stops most errors before they reach the square feet calculator. Measure twice if a wall looks uneven.
Why Use Our Square Footage Calculator
It handles five shapes, many areas at once and every common unit, including feet and inches typed together. You get square feet, square meters, square yards, square inches and acres in one view. Waste and cost are built in, and nothing you enter leaves your browser. Measure your space and get your total now.
Frequently asked questions
Is this square footage calculator free?
Yes, it is free with no sign up and no limit.
How to calculate square footage for a rectangle?
Multiply the length by the width, both in feet.
What is the square footage of a room that is 10 by 12 feet?
It is 120 square feet.
Can the square feet calculator handle odd shapes?
Yes, split the space into simple shapes and add each one as its own area.
How many square feet are in a square meter?
One square meter equals about 10.764 square feet.
Is this the same as an area calculator?
Yes, it finds area, with results focused on square feet for home projects.
How much extra flooring should I buy?
Add 5% to 10% for most layouts and about 15% for diagonal tile.
Does the square feet calculator work in meters?
Yes, choose meters and it converts the total to square feet and square yards.
Does the square feet calculator include closets?
Only if you add them as their own areas.
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