Square Foot Calculator — Free Square Footage Calculator

How to Calculate Square Feet (the Quick Version)

If you only want the math, here it is. Multiply the length by the width, with both in feet. That is how to calculate square feet for any rectangle. A room 12 feet by 15 feet is 12 × 15 = 180 square feet, usually written as 180 sq ft.

People ask this in a lot of different ways: how to figure out square footage, how to determine square footage, how to calculate the square feet of a room. It is the same job every time. Measure the two sides, get them into feet, multiply, then add or subtract for anything that isn’t a plain rectangle.

If your tape shows feet and inches, divide the inches by 12 and add them to the feet. A wall of 5 ft 8 in is 5.667 ft, and one of 11 ft 4 in is 11.333 ft. Multiply them and you get 64.2 sq ft. The calculator above does this for you if you choose the “ft + in” unit.

A few habits make measuring more reliable. Sketch the room first so you have somewhere to write each number. Measure along the base of the wall, not at the top of the baseboard. Take every measurement twice, and if two opposite walls disagree, use the bigger one when you order material.

Square Footage of a Room, House, Wall and Countertop

These four come up more than anything else, so here is how each one works in practice.

How to calculate the square footage of a room

Measure the length and width of the floor and multiply. A living room of 18 ft by 14 ft is 252 sq ft. If the room has an alcove or a cut-out corner, use the L-shaped option: enter the overall length and width, then the size of the missing piece, and the calculator subtracts it.

How to calculate the square footage of a house

There are two usual methods. Room by room, you measure every finished room, hallway and closet and add the areas. This measures inside the walls, so it comes out a little smaller than a listing. The outside method multiplies the outer length and width of each floor. A simple house of 40 ft by 30 ft has 1,200 sq ft per floor, or 2,400 sq ft over two floors. Garages, porches and unfinished basements normally don’t count as living area, and the rules vary by region and lender, so ask an appraiser if the number affects a sale or a loan.

How to figure out the square footage of a wall

Multiply the wall length by its height, then take away the doors and windows. Wall mode does this in one step: enter the opening size and how many there are. For openings of different sizes, subtract the extra ones by hand.

How to figure out the square footage of a countertop

Most kitchen counters are about 25 inches deep. Measure the length and depth in inches, multiply, then divide by 144. A run of 96 inches by 25.5 inches is 2,448 sq in, which is 17 sq ft. For an L-shaped counter, split it into two rectangles and count the corner square only once. When you are getting a price, don’t subtract the sink cutout. Fabricators usually charge for the full slab, so ask what the quote includes.

Rectangle, triangle and circle

A rectangle is length × width. A triangle is half of base × height, so a base of 10 ft and a height of 7 ft gives 35 sq ft. The height must be measured at a right angle to the base. For a circle, the calculator asks for the diameter. A patio 10 ft across is about 78.54 sq ft. If you only measured the radius, double it first.

Square Foot Calculator for Flooring and for Measurements in Inches

For flooring, you never buy exactly the area of the room. Take a 180 sq ft room. With 10 percent waste you order 198 sq ft. If each box covers 22.5 sq ft, 198 ÷ 22.5 is 8.8, so you buy 9 boxes. At $4.20 per sq ft, the material comes to $831.60. Put the waste, the price and the box coverage into the calculator and it gives you these numbers directly.

If your measurements are in inches, you don’t have to convert anything by hand. Type 96″ or switch a field to inches, and the calculator handles the conversion. You can also use “ft + in” and enter feet and inches in separate boxes, which is the easiest option when your tape reads something like 12 ft 7 in.

Square Feet to Square Inches, Square Yards and Square Meters

Converting an area trips people up for one reason. A foot is 12 inches, but a square foot is 12 inches by 12 inches, so it holds 144 square inches, not 12. When you convert an area, the factor gets squared too.

To change sq ft to sq in, multiply by 144. To change sq in to sq ft, divide by 144. A panel that is 30 inches by 48 inches is 1,440 square inches, which is 10 square feet.

If you came here looking for a “square to square feet calculator”, you most likely have an area in square meters or square yards. Set the unit on each measurement field, and the results panel shows the same area in square feet, square inches, square yards, square meters and acres at once. For reference, 1 square yard is 9 sq ft and 1 square meter is about 10.764 sq ft.

Common Mistakes When You Figure Out Square Footage

Most wrong answers come from a short list of slips. It is worth knowing them before you start, because each one can cost you a second trip to the store.

• Mixing units. Feet times inches gives a number that means nothing. Convert everything to the same unit first, or let the calculator do it.
• Dividing square inches by 12. The right divisor is 144, because a square foot is 12 inches by 12 inches.
• Forgetting the doors and windows. For paint and wallpaper, openings reduce the area you need.
• Forgetting waste. Flooring and tile always produce offcuts, so the area you buy is bigger than the area of the room.
• Measuring once. Walls are rarely straight. Measure twice, and if opposite walls differ, use the larger number for ordering.
• Typing a radius where a diameter is needed. The circle, ellipse and circle border shapes ask for full measurements across. Double a radius before you enter it.
• Using the slanted side as a triangle’s height. The height is always measured at a right angle to the base.
• Rounding too early. Keep the decimals until the last step, then round up for ordering.
• Counting the wrong spaces in a listing. Garages, porches and unfinished basements are normally left out of living area.

Before You Place an Order: A Quick Checklist

A few minutes of checking at this stage saves the most money. Go through these before you pay for anything.

• Re-measure the room on site, even if you already have a number from a floor plan.
• Check the coverage printed on the box. It differs between products, even within one brand.
• Ask your installer what waste percentage they recommend for your layout and material.
• Ask whether unopened boxes can be returned, and what the policy is on batches and shades.
• Plan to keep one spare box for future repairs, since a later batch can be a slightly different colour.
• Save or print your calculation, so you can compare quotes against your own numbers.

Square Footage Cheat Sheet

More Free Calculators

If you need something more specific, these pages go deeper on one job:

• Square feet to square inches converter (replace # with your converter page URL)
• Cost per square foot calculator (replace # with your cost page URL)

Frequently Asked Questions