Calculate square footage for a room, floor, wall, or multiple spaces. Add or subtract sections, convert square feet to square meters, and estimate material or project cost.
Square Footage Calculator
Choose a mode, enter your measurements, and press Calculate for an instant area.
ft
in
ft
in
Enter whole feet plus inches, for example 12 ft 6 in. Leave the second box at 0 if you only have a whole-foot measurement.
Up to 30 rows. Each row's length times width times quantity is added to the total.
Divide the room into simple rectangles. Add each included rectangle below, then use Subtract an Area for any open or excluded space, such as a cutout.
Rectangles to Add
Areas to Subtract (optional)
ft
in
ft
in
Use this to calculate several walls of the same length and height at once, such as all four walls of a room.
Doors, Windows & Openings (optional)
Subtracting openings is optional. It depends on your project, so only add an opening if you want it removed from the wall area.
ft
Useful for round patios, rugs, garden beds, and other circular floors.
Optional: Material Allowance & Cost
This is a planning allowance, not a required waste figure. Actual waste depends on material, layout, cutting, pattern, installer, and room shape.
%
$
Material/project estimate from entered unit price. This does not include labor, tax, adhesive, underlayment, delivery, or other project costs unless you enter them yourself.
For a rectangular space, square feet equals length in feet times width in feet. If a room is 12 feet long and 10 feet wide, then 12 times 10 equals 120 square feet.
Visual: Rectangle Area
Area equals length times width. Both measurements must be in the same unit before you multiply them.
Rectangle area formula
Length
Width
Area
12 ft
10 ft
120 ft²
The formula is simple when the room is a perfect rectangle. Real spaces can be more complicated, which is why a useful square footage calculator should also handle feet and inches, multiple rooms, L-shaped spaces, openings, walls, and circular areas.
What Does One Square Foot Mean?
A square foot is an area measuring 1 foot long by 1 foot wide. It is a unit of area, not length, and that distinction matters. A room that is 10 feet long is not automatically 10 square feet. You need both dimensions. Ten feet by ten feet is 10 times 10, or 100 square feet.
Visual: One Square Foot
One square foot is a square that is 1 foot long on every side, not simply a length of 1 foot.
Definition of one square foot
Length
Width
Area
1 ft
1 ft
1 ft²
How Do I Calculate Square Footage With Feet and Inches?
Suppose a room is 12 ft 6 in by 10 ft 3 in. Convert the extra inches to a fraction of a foot. Six inches is 6 divided by 12, or 0.5 foot, so 12 ft 6 in equals 12.5 ft. Three inches is 3 divided by 12, or 0.25 foot, so 10 ft 3 in equals 10.25 ft. Multiplying 12.5 by 10.25 gives 128.125 square feet. The Rectangle / Square mode above accepts feet and inches separately so you do not need to do this conversion by hand.
Example
12 ft 6 in × 10 ft 3 in = 12.5 ft × 10.25 ft = 128.125 ft².
How Do I Calculate Multiple Rooms?
Calculate each room individually, then add the results. For example, a living room at 15 ft by 12 ft is 180 square feet, a bedroom at 12 ft by 10 ft is 120 square feet, a second bedroom at 11 ft by 10 ft is 110 square feet, and a hall at 12 ft by 4 ft is 48 square feet. Adding 180, 120, 110, and 48 gives a total of 458 square feet. The Multiple Rooms mode above displays each individual area along with the combined total automatically.
How Do I Calculate an L-Shaped Room?
Split the L shape into rectangles. Do not multiply the longest overall length by the longest overall width, because that can include space that is not actually part of the room. Suppose rectangle A is 20 ft by 15 ft, which is 300 square feet, and rectangle B is 8 ft by 6 ft, which is 48 square feet. The total is 300 plus 48, or 348 square feet.
Visual: L-Shaped Room Split Into Two Rectangles
An L-shaped room splits into Rectangle A and Rectangle B. Calculate each rectangle, then add them together.
L-shaped room split into rectangles
Section
Length
Width
Area
Rectangle A
20 ft
15 ft
300 ft²
Rectangle B
8 ft
6 ft
48 ft²
Total
348 ft²
The same technique works for many irregular rooms. Break the area into simpler shapes, calculate each shape, add the included pieces, and subtract excluded pieces.
How Do I Subtract an Open Area?
Suppose the combined rectangular area is 348 square feet, but a 4 ft by 3 ft section is open or excluded. The excluded area is 4 times 3, or 12 square feet. The net area is 348 minus 12, or 336 square feet. The L-Shaped / Irregular Area mode above shows this subtraction directly rather than silently returning a smaller number.
How Do I Calculate Wall Square Footage?
For a rectangular wall, multiply length by height. A 12-foot wall that is 8 feet high is 12 times 8, or 96 square feet. If there is a 3 ft by 7 ft door, the door area is 21 square feet, so the net wall area is 96 minus 21, or 75 square feet. Repeat for each wall and add them when calculating an entire room.
Visual: Gross Wall Area Minus Openings
Gross wall area minus door and window area equals net wall area, useful for paint, wallpaper, tile, and paneling.
Wall area minus openings
Step
Value
Gross wall area (12 ft × 8 ft)
96 ft²
Door opening (3 ft × 7 ft)
−21 ft²
Net wall area
75 ft²
Should I Subtract Windows and Doors?
It depends on why you are calculating the wall area. For a precise material estimate, large openings can matter. For some paint estimates, a user may choose not to subtract small openings, since the extra material can help cover waste or additional coats. The Wall Area mode lets you decide. It does not force one project practice, and openings are only subtracted when you add them.
How Do I Calculate a Circular Area?
Use area equals pi times radius squared. Suppose a circular patio has a diameter of 12 feet. The radius is 12 divided by 2, or 6 feet. The area is pi times 6 squared, which is about 113.10 square feet. This is useful for circular patios, round rugs, garden beds, and other circular spaces.
Area = π × radius²
Square Feet to Square Meters
NIST conversion relationships give 1 square foot equals 0.09290304 square meter. So 100 square feet equals 9.290304 square meters, and a 1,000 square foot area is approximately 92.903 square meters. The calculator keeps sufficient internal precision and displays a sensible rounded answer.
Square Meters to Square Feet
Reverse the conversion. One square meter is approximately 10.7639104 square feet, so 100 square meters is approximately 1,076.39 square feet. The exact displayed decimal count can depend on rounding.
Square Feet to Square Yards
One yard equals three feet, so one square yard is 3 ft times 3 ft, or 9 square feet. Square yards equals square feet divided by 9. For example, 450 square feet divided by 9 equals 50 square yards.
How Many Square Feet Are in an Acre?
One acre contains 43,560 square feet. So 0.5 acre equals 21,780 square feet, and two acres equals 87,120 square feet. Land-area conversions can be useful, but this page remains primarily focused on practical room, wall, and floor area.
How Much Flooring Do I Need?
The measured floor area is the starting point. Some flooring installations require additional material for cuts, pattern matching, damaged pieces, future repairs, and irregular shapes. The appropriate allowance depends on the material and installation, so this calculator lets you choose an optional planning percentage rather than automatically adding 10%.
Visual: Measured Area Plus Planning Allowance
A 10% allowance on a 500 square foot measured area adds 50 square feet, for a 550 square foot planning area.
Measured area plus a 10 percent planning allowance
Component
Value
Measured area
500 ft²
10% allowance
+50 ft²
Planning area
550 ft²
If the measured area is 500 square feet and you choose 10%, then 500 times 0.10 equals 50 additional square feet, for a planning area of 550 square feet.
Is 10% Extra Material Always Enough?
No. Some straightforward installations may need less. Diagonal patterns, unusual layouts, highly irregular rooms, or fragile materials may need more. The manufacturer or installer may provide a project-specific recommendation. This calculator shows exactly how much came from the measured area and how much came from the selected allowance.
How Do I Calculate Cost Per Square Foot?
If an item costs $4.50 per square foot and the planning area is 550 square feet, then 550 times $4.50 equals $2,475. That is a basic area-based cost. It may not include labor, delivery, tax, adhesive, underlayment, trim, subfloor work, or equipment. Treat this as an estimate based on the entered price.
Square Footage for Tile
Tile projects depend on floor or wall area, and this calculator can determine the net square footage. For tile-specific quantities, tile size, grout lines, layout, and piece count, use the Tile Calculator.
Square Footage for Concrete
Square footage tells you the surface area. Concrete requires volume because thickness matters. A 100 square foot slab that is two inches thick does not require the same concrete quantity as 100 square feet that is six inches thick. Use the Concrete Calculator when thickness must be included.
Square Footage for Roofing
A roof is not always equal to the building footprint. Slope and roof geometry can increase the surface area. Use the dedicated Roofing Calculator for roof material calculations rather than using ground-floor square footage alone.
Is This My Home's Official Square Footage?
Not necessarily. This calculator performs geometric area math from the measurements entered. Real-estate listings, appraisals, tax records, building codes, and professional measurement standards can have specific rules about which areas count, with different treatment of garages, unfinished rooms, low ceilings, below-grade areas, porches, stairs, and open-to-below spaces. Do not use this calculator as proof of official gross living area, an appraisal figure, or a legally defined floor area.
Why Area Conversions Are Squared
One foot equals 0.3048 meter, but one square foot is not 0.3048 square meter, because area has two dimensions. So 1 ft² equals 0.3048 m times 0.3048 m, which is 0.09290304 m². This is why applying a normal length conversion factor directly to square footage gives the wrong answer. This calculator always applies the squared area factor, never the plain linear one.
The Bottom Line
For a rectangle, length times width equals square footage. For irregular spaces, divide them into simpler shapes. For walls, subtract openings when appropriate. For multiple rooms, calculate each section and add them. This calculator shows both the individual math and the total so you can verify exactly how the area was determined.
Worked Examples
Rectangle
Length 12 ft, width 10 ft.
12 × 10 = 120 ft²
120 ft²
Feet and Inches
12 ft 6 in by 10 ft 3 in.
12.5 × 10.25 = 128.125 ft²
128.125 ft²
L-Shaped Room
Rectangle A 20×15, Rectangle B 8×6.
300 + 48 = 348 ft²
348 ft²
Subtracting an Opening
348 ft² total, minus a 4×3 excluded area.
348 − 12 = 336 ft²
336 ft²
Wall Minus a Door
12 ft × 8 ft wall, minus a 3×7 door.
96 − 21 = 75 ft²
75 ft²
Circle
12-ft diameter circular patio.
π × 6² ≈ 113.097 ft²
113.097 ft²
Planning Allowance
500 ft² measured, plus a 10% allowance.
500 + 50 = 550 ft²
550 ft²
Square Feet to Square Meters
1,000 ft² converted to square meters.
1000 × 0.09290304 = 92.90304 m²
92.90304 m²
Try It Yourself
A wall is 12 ft long and 8 ft high, with one 3 ft by 7 ft door.
What is the net wall area?
Gross area is 12 × 8 = 96 ft². The door is 3 × 7 = 21 ft². Net area is 96 − 21 = 75 ft².
Which Calculator Do I Need?
Square Footage Calculator (this page)
I want the area of a room, floor, wall, multiple sections, or a circle, in square feet, square yards, or square meters.
Multiply the length of the space in feet by its width in feet. For a room that is 12 feet long and 10 feet wide, the square footage is 12 times 10, or 120 square feet.
How many square feet is a 10x10 room?
A 10 ft by 10 ft room is 10 times 10, or 100 square feet.
How many square feet is a 12x12 room?
A 12 ft by 12 ft room is 12 times 12, or 144 square feet.
How many square feet is a 12x20 room?
A 12 ft by 20 ft room is 12 times 20, or 240 square feet.
How do I calculate feet and inches square footage?
Convert the inches portion to a decimal fraction of a foot by dividing by 12, then multiply the two decimal lengths together. For example, 12 ft 6 in by 10 ft 3 in becomes 12.5 ft by 10.25 ft, which equals 128.125 square feet.
How do I calculate several rooms?
Calculate each room's area separately, then add the individual results together. The Multiple Rooms mode above lists each area and shows the combined total automatically.
How do I calculate an L-shaped room?
Split the L shape into two or more simple rectangles, calculate each rectangle's area, and add them together. Do not multiply the overall outer length by the overall outer width, since that can include space that is not part of the room.
How do I calculate an irregular room?
Break the irregular space into simpler rectangles, calculate each one, then add the included pieces and subtract any excluded or open pieces.
How do I subtract an opening?
Calculate the opening's own area, its length times its width, then subtract that figure from the combined rectangle total to get the net area.
How do I calculate wall square footage?
Multiply the wall's length by its height. For a 12 ft wall that is 8 ft high, the area is 12 times 8, or 96 square feet.
Should I subtract windows and doors?
It depends on the project. For a precise material estimate, subtracting large openings can matter. For some paint estimates, a user may choose not to subtract small openings since the extra material can help cover additional coats. This calculator lets you decide by entering openings only if you want them subtracted.
How do I calculate circular square footage?
Use the formula pi times radius squared. If a circular patio has a 12 ft diameter, the radius is 6 ft, and the area is pi times 6 squared, or about 113.097 square feet.
How do I calculate square footage for flooring?
Measure the floor area using the appropriate mode above, then optionally add a planning allowance for cuts and waste before buying material.
How much extra flooring should I buy?
It depends on the material and installation method. Straightforward layouts may need less extra material, while diagonal patterns, unusual layouts, or fragile materials may need more. Check with the manufacturer or installer for a project-specific recommendation.
Should I add 10% waste?
Ten percent is a common planning allowance for many flooring projects, but it is not a universal rule. This calculator lets you choose 5%, 10%, 15%, or a custom percentage rather than automatically adding one.
How do I calculate cost per square foot?
Multiply your area, or planning area if you are using an allowance, by the price per square foot. For example, 550 square feet at $4.50 per square foot equals $2,475.
How do I convert square feet to square meters?
Multiply square feet by 0.09290304. For example, 1,000 square feet equals 1,000 times 0.09290304, or 92.90304 square meters.
How many square meters is 1,000 square feet?
1,000 square feet equals approximately 92.903 square meters.
How do I convert square meters to square feet?
Multiply square meters by approximately 10.7639104. For example, 100 square meters equals about 1,076.39 square feet.
How many square feet are in a square yard?
One square yard equals 9 square feet, since one yard is 3 feet on each side.
How many square feet are in an acre?
One acre equals 43,560 square feet.
Is square footage the same as cubic footage?
No. Square footage measures area, which has two dimensions. Cubic footage measures volume, which has three dimensions and includes thickness or depth, such as for concrete.
Can I use this for concrete?
This calculator gives you the surface area, which is a useful starting point. Concrete projects also depend on thickness, so use the Concrete Calculator when you need a volume estimate.
Can I use this for roofing?
Square footage from this calculator reflects ground or floor area. A roof's actual surface area can be larger because of slope and roof geometry, so use the Roofing Calculator for roofing material estimates.
Can I use this for tile?
Yes, for determining the net area to cover. For tile-specific quantities such as piece count, tile size, and grout lines, use the Tile Calculator.
Is calculated room area the same as official home square footage?
Not necessarily. This calculator performs geometric area math from the measurements you enter. Real-estate listings, appraisals, tax records, and building codes can have specific rules about which spaces count, so this tool should not be treated as an official measurement of record.
Why is one square foot 0.09290304 square meters?
One foot equals 0.3048 meter, but area has two dimensions, so one square foot equals 0.3048 meter times 0.3048 meter, which is 0.09290304 square meter. Applying the plain linear conversion factor to an area figure gives the wrong answer.
Sources & Further Learning
National Institute of Standards and Technology: Guide for the Use of the International System of Units (SI), used here for the foot-to-meter and square-foot-to-square-meter conversion relationships - nist.gov/pml/special-publication-811
Bureau International des Poids et Mesures: The International System of Units (SI Brochure), used here for metre and square-metre measurement context - bipm.org/en/publications/si-brochure
Methodology & Limitations
All area math is pure geometry based on the lengths, widths, and quantities entered, using the exact area factor 0.09290304 square meter per square foot rather than a plain linear conversion.
Feet-and-inches and meters-and-centimeters entries are converted to decimal feet internally before any multiplication, preserving the exact inch or centimeter value entered.
The material allowance is a planning figure the user selects. It is never applied automatically, and it is not a claim about actual installation waste.
Any cost shown is a simple area times unit-price estimate. It does not include labor, tax, adhesive, underlayment, delivery, or other project costs unless entered separately.
This calculator does not determine official real-estate, appraisal, tax-assessor, or code-defined floor area, which can follow different rules about which spaces count.
This calculator performs geometric area math from the measurements you enter. It is a planning and estimating tool, not an official measurement of record. Real-estate listings, appraisals, tax records, building codes, and professional measurement standards can define included and excluded spaces differently, so results here should not be used as proof of official gross living area or legally defined square footage. Any material allowance shown is a planning figure you select, not a guaranteed or required waste amount, and any cost shown is a simple estimate based on the price you enter.