Room Square Footage Calculator

Getting the square footage of a room comes down to one idea: multiply length by width. The tool below handles the arithmetic, including feet-and-inches measurements and rooms that aren't a clean rectangle. Type in your dimensions, and you get the area in square feet plus a running total if you're measuring more than one space.

How to calculate the square footage of a room

For a plain rectangular room, measure the length of one wall and the width of an adjacent wall, then multiply them together. Length times width gives you the area in square feet, as long as both numbers are in feet.

A room that measures 12 feet by 16 feet works out to 192 square feet (12 x 16 = 192). A square 12 by 12 bedroom is 144 square feet. That's the whole formula. The part people get wrong isn't the multiplication, it's the measuring.

Use a steel tape or a laser distance meter and measure at floor level, wall to wall. Pull the tape tight so it doesn't sag. If a wall reads 14 feet 6 inches, don't round it off in your head. Six inches is half a foot, so that dimension is 14.5 feet. Our feet and inches calculator converts mixed measurements for you if you'd rather not do the fractions by hand, and the pillar guide on how to calculate square footage walks through the same math for larger areas.

Worked example

Say you're carpeting a bedroom. You measure the long walls at 15 feet 3 inches and the short walls at 11 feet 8 inches.

15 feet 3 inches = 15.25 feet
11 feet 8 inches = 11.667 feet
15.25 x 11.667 = about 178 square feet

Round up when you're buying material. A bedroom that calculates to 178 square feet should be ordered as roughly 180 to 195 square feet once you add a waste factor for cuts and seams.

L-shaped and odd-shaped rooms

Most rooms aren't a perfect box. Bump-outs, angled walls, and open floor plans throw people off, but the fix is simple: break the room into rectangles, calculate each one, and add the totals. This is the single most common piece of advice you'll see in DIY circles. In an AnandTech home forum thread on measuring a room with odd wall sizes, the answers all point the same direction, split the space into shapes you can measure, then sum them.

For an L-shaped room, draw the outline on paper and slice it into two rectangles. Measure each rectangle separately.

Rectangle A: 10 feet x 12 feet = 120 square feet
Rectangle B: 8 feet x 6 feet = 48 square feet
Total: 168 square feet

If a room has an angled corner or a triangular nook, treat that piece as a triangle: base times height divided by two. A 4 foot by 3 foot triangular corner adds 6 square feet (4 x 3 / 2). Rounded rooms or bay windows can be estimated as part of a circle, but for flooring you can usually box them in and accept a little extra material.

Step by step: a room with a bay window

A bay window is a shallow bump-out, usually three angled panes that push the floor out past the main wall. Handle it as a small trapezoid or, if you want to keep the math simple, box it in.

Measure the main rectangle first. Say the room is 14 feet by 13 feet, which is 182 square feet.
Measure the bay separately. Measure how far it projects from the wall (the depth) and the width of the flat front pane, plus the width where it meets the wall. A typical bay projects 18 to 24 inches.
For a bay that is 2 feet deep, 6 feet wide at the wall, and 3 feet wide across the front pane, average the two widths: (6 + 3) / 2 = 4.5 feet. Then 4.5 x 2 = 9 square feet.
Add it to the main room: 182 + 9 = 191 square feet.

If you'd rather not fuss with the trapezoid, box the bay as a full 6 by 2 rectangle (12 square feet). You'll overstate the floor by about 3 square feet, which is fine for ordering flooring and gives you a little extra for cuts. It is not fine if you're reporting a home's official size, where the angled walls get measured properly.

Step by step: a room with a closet

A closet is just a second rectangle attached to the room. Whether you fold it in depends on the job, but for flooring and paint you almost always include it.

Measure the main room. A 12 by 11 bedroom is 132 square feet.
Measure the closet opening and its depth. A reach-in closet might be 5 feet wide by 2 feet deep, which is 10 square feet. A walk-in could be 6 by 5, or 30 square feet.
Add the closet to the room. With the reach-in: 132 + 10 = 142 square feet. If you skip that 10 square feet, you come up a box of flooring short at the worst possible time.
For a walk-in with its own light fixture and a door, some people measure it as its own space. The math is the same either way, you're adding rectangles.

Closets, alcoves, and what to include

Whether a closet counts depends on why you're measuring. For flooring, include the closet if you're putting the same floor inside it, because you have to buy material for that space. For a room's listed dimensions in a real estate sense, closets are generally part of the finished area of the house already. Alcoves, window seats, and shallow bump-outs get measured to the wall the same way.

Ceilings and sloped walls

Floor area doesn't care about ceiling height, so a standard room's square footage is the same whether the ceiling is 8 feet or 12 feet. The exception is finished attic and bonus rooms with sloped ceilings. Under the measurement standard used by appraisers, only the portion of a sloped-ceiling room with at least 7 feet of clearance counts toward finished area, and you need at least half the floor at that height for any of it to count. For your own flooring or paint math, that rule doesn't matter, you still floor the whole floor.

What to measure: flooring vs paint vs baseboards

Same room, three different numbers. Get clear on which one you need before you buy anything.

Job	What you measure	Formula	Include the closet?
Flooring, carpet, tile	The floor	Length x width, plus closets, minus fixtures you won't cover	Yes, you floor it
Paint (walls)	The walls	Perimeter x ceiling height, minus doors and windows	Usually, walls are walls
Paint (ceiling)	The ceiling	Same as the floor area	No, closet often skipped
Baseboard, trim, crown	The perimeter (linear feet)	Add up wall lengths, subtract door openings	Yes if trimmed

Flooring is a floor number. Paint is a wall number. Baseboard is a linear number, measured in running feet along the base of the wall, not square feet. For a 12 by 16 room with 8 foot ceilings, the floor is 192 square feet, the walls are about 448 square feet before openings (perimeter of 56 feet x 8), and the baseboard run is about 52 feet after you subtract a 3 foot doorway. Three answers, one room.

For flooring specifically, add a waste factor once you have the floor number. The flooring calculator does that step for you.

Common room-size reference table

Handy for sanity-checking a measurement or estimating a space you can't get into yet. These are typical US ranges, not rules.

Room	Common dimensions	Approx. square feet
Small bedroom	10 x 10	100
Standard bedroom	11 x 12	132
Master bedroom	14 x 16	224
Standard bathroom	5 x 8	40
Living room	16 x 20	320
Kitchen	12 x 12	144
Dining room	11 x 14	154
One-car garage	12 x 20	240

Home building references put the average US standard bedroom around 11 by 12 feet, with master bedrooms commonly running 14 by 16 or larger. If your measurement lands wildly outside these ranges, re-check the tape before you order material.

Laser vs tape: which to use

A steel tape is cheap, always works, and is accurate over short spans. Its weakness is long or awkward rooms, where the tape sags, kinks, or needs a second person to hold the dumb end.

A laser distance meter shines a dot on the far wall and reads the distance in a second, to about an eighth of an inch. For a house full of rooms, it's faster and you can measure solo. A few tips:

Hold the laser flat against the near wall and aim square at the opposite wall. A crooked shot reads long.
In bright rooms the red dot can wash out. Look for the on-screen number, not the dot, or use a green-beam model.
Lasers measure to whatever they hit, so a mirror, a window, or an open doorway can give a false reading. Aim at solid wall.
For a floor plan, measure at floor level along the baseboard. Furniture in the way is the main reason people measure high and get a bad number.

Whichever tool you use, measure twice. A single fat-fingered reading is the most common source of a wrong square footage.

Common mistakes

Measuring in inches and forgetting to convert. A room isn't 180 feet long. If you measured in inches, divide by 12 first.
Rounding too early. Round the final area, not each wall.
Ignoring the bump-out. That little jog by the closet is real square footage. Break it out as its own rectangle.
Measuring drywall to drywall for a house total. For flooring that's fine. For the home's official size, appraisers measure differently. See the house square footage calculator for how gross living area is figured.

Frequently asked questions

How do you calculate the square footage of a room?

Multiply the length of the room by its width, with both measurements in feet. A 12 foot by 14 foot room is 168 square feet. For rooms that aren't rectangular, split the space into rectangles and triangles, calculate each piece, and add them together.

How do you measure the square footage of a room with feet and inches?

Convert the inches to a decimal by dividing by 12, then multiply. A wall that is 13 feet 6 inches becomes 13.5 feet. So a 13 feet 6 inch by 10 foot room is 135 square feet. The calculator above accepts feet and inches directly so you don't have to convert first.

Do closets count in a room's square footage?

For flooring and paint, yes, because you have to buy material to cover them. Measure the closet as its own rectangle and add it to the room. In a home's official finished square footage, closets are already part of the living area of the house.

How do I find the square footage of an L-shaped room?

Divide the L into two rectangles. Measure the length and width of each, multiply to get each area, then add the two areas together. If you're not sure where to split it, cut along the line that gives you two clean rectangles with no overlap.

How do you measure a room with a bay window?

Measure the main rectangle, then measure the bay as its own shape. Average the width where it meets the wall and the width of the front pane, then multiply by how far the bay projects. Add that to the main room. For flooring you can box the bay in as a full rectangle to leave a little extra for cuts.

How much extra should I add for flooring?

Add roughly 5 to 10 percent to your calculated square footage for waste, cuts, and pattern matching. Tile and plank floors with a diagonal or herringbone layout need more, closer to 15 percent.

How do I measure a room for baseboard?

Baseboard is measured in linear feet, not square feet. Add up the length of every wall at floor level, then subtract the width of door openings, since you don't trim across a doorway. A 12 by 16 room has a 56 foot perimeter, so about 52 to 53 feet of baseboard after one door.

What's a normal size for a bedroom?

A standard US bedroom runs around 10 by 10 up to about 12 by 12, which is 100 to 144 square feet. Master bedrooms are usually 14 by 16 or larger. Anything under about 70 square feet with a proper closet and egress window can still qualify as a legal bedroom in many areas, but it feels tight.

Sources

Related tools: House Square Footage Calculator, Feet and Inches Calculator, Flooring Calculator, and the how to calculate square footage guide. You can always start from the homepage to find another tool.