Square Footage Calculator

How to calculate square footage

Square footage measures a flat 2D area in feet. Measure each side in the same unit, convert to feet if needed, then apply the formula for your shape. The calculator does the conversions and multiplies by quantity when you have matching rooms.

Example: a room that is 12 ft long and 10 ft wide has an area of 12 × 10 = 120 sq ft.

Square footage formula

The most common formula for rooms and rectangular spaces is length multiplied by width.

How to calculate square feet for a room

1. Measure length and width

   Use a tape measure along the longest walls. Note closets or alcoves separately if they also need flooring.

2. Multiply for area

   Example: 15 ft × 12 ft = 180 sq ft for the main room.

3. Add extras and waste

   Add closet or hallway areas, then apply a waste percentage before you order materials.

Square footage calculator for different shapes

Use the shape selector in the tool, or apply these formulas by hand.

Square feet to square meters conversion

One square meter equals about 10.764 square feet. To convert: m² = ft² ÷ 10.764. Example: 120 sq ft ÷ 10.764 ≈ 11.15 m². The results panel also shows square yards and square inches.

How much flooring do I need?

Start with net square footage, then add a waste percentage for cuts and mistakes.

How to calculate cost per square foot

Enter an optional price per square foot. Estimated cost uses the waste-adjusted area: cost = order area × price per ft². For a full project budget, also add underlayment, labor, and trim.

Common square footage calculations

Related tools

Need volume instead of area? Try the cubic yard calculator or the gravel calculator for landscaping material estimates.

Area is not volume

Square footage is the floor, the wall, or the ceiling as a flat shape. A room 12 feet by 10 feet is 120 square feet whether the ceiling is 8 feet high or 10 feet high. Height becomes relevant only when you are buying something measured by volume, such as mulch or gravel. Those belong on the cubic yard calculator and the gravel calculator. Staying on this page when you have a length and a width, and moving on when you also have a depth, is the split that keeps an order from being short by a whole dimension.

Rectangles use length times width. A square is the same formula with equal sides. A right triangle is half of the rectangle that shares its legs, so base times height divided by two. A circle uses pi times radius squared. Measure the diameter and halve it before you square. Mixing diameter and radius is a fourfold error, not a small one. Convert every side into the same unit before you multiply. Inches times feet is not square feet.

Waste, pattern match, and cost per square foot

Material is sold in rectangles, planks, and rolls. A room is rarely the same shape, and cuts at doors and closets leave pieces you cannot reuse. A waste percentage adds that allowance on top of the geometric area. Ten percent of 120 square feet is 12, so you price 132 square feet. Tile with a repeating pattern, or boards laid on a diagonal, often needs more than a straight lay. Increase the percentage when the supplier or the installer names a higher waste factor. Do not invent a large percentage to hide a bad measurement. Re-measure the room first.

Cost on this page is area after waste times a price per square foot. It is a material estimate, not a bid. It leaves out underlayment, adhesive, labor, tax, and delivery. If the price you were quoted is per square yard, convert it before you type. One square yard is 9 square feet, so a price per square yard divided by 9 is the price per square foot. Typing the square-yard price into a square-foot field multiplies the budget by nine.

Rooms that are not one rectangle

An L-shaped room is two rectangles. Measure each rectangle, compute each area, and add them. Overlap the rectangles only on paper in a way that does not count the corner twice. A bay window that sticks out is a third rectangle or a shape you approximate. Closets you will not floor can be subtracted if you are sure the material stops at the opening. Doors and cabinets that sit on the floor you are covering should stay in the area. You still buy material under them only if the plan says so. When the shape is a circle or a half-circle, use the circle formula and halve it for a semicircle rather than forcing the space into a rectangle that is much larger.

Stairs and landings are separate areas. A stair tread is a series of small rectangles. Add them if you are covering the treads. The vertical risers are a different surface and a different product. Walls use height times width, minus windows and doors you will not cover. This calculator will multiply the numbers you give it. Label each result with the surface so a wall area is not later ordered as flooring.

Unit conversions you will actually need

There are 144 square inches in a square foot, because 12 times 12 is 144. There are 9 square feet in a square yard. A square meter is about 10.764 square feet. If you measure in meters and the store sells in square feet, convert the area once at the end rather than converting each side and rounding early. Rounding each side to the nearest inch is usually fine for a room. Rounding a radius to the nearest foot is not, because the radius is squared.

Write the measurements on a sketch before you type. A 12-foot wall that is actually 12 feet 6 inches is 12.5 feet. Half a foot across a 10-foot depth is 5 square feet, which is enough to matter on an expensive material and easy to miss if you drop the inches. After the calculator shows an area, multiply length and width once by hand for the main rectangle. If those two numbers disagree, the unit dropdown is the first place to look.

What this page will not estimate

Paint coverage depends on the product’s stated square feet per gallon and on whether you need two coats. Take the wall area from this page and divide by the number printed on the can. The calculator does not store paint brands. Carpet and vinyl rolls have a width. An area that is correct in square feet can still waste a roll if the room is wider than the goods. Ask the supplier how the roll is cut. Flooring labor is quoted in its own units. Do not treat the material cost line as the project cost.

Outdoor areas that need a depth, such as a gravel pad or a mulch bed, are volumes. Compute the square footage if you want the footprint, then open the cubic yard calculator and supply the depth. Gravel sold by the ton needs the gravel calculator, which applies a density after the volume exists. Ordering tons from a square-foot total skips the depth and the weight, and the delivery will be wrong in a way a waste percentage cannot fix.

Square footage FAQs