Square Footage Calculator
Find the area of a room, floor, or measured section in square feet and square metres. Calculate a rectangle, combine up to 50 rectangular areas, or use circle and triangle modes with measurements in feet, inches, metres, or centimetres.
Total area
120 ft²
How to Use the Square Footage Calculator
Choose the shape that matches the space you want to measure. Use Rectangle for a typical room, Multiple rectangular areas for several rooms or an irregular floor plan, or select Circle or Triangle when those shapes fit the area.
Select the unit used for your measurements, then enter the required dimensions. You can work in feet, inches, metres, or centimetres without converting the lengths first.
The result is shown in both square feet (ft²) and square metres (m²). In multiple-area mode, the calculator also shows the area of each section before combining them into one total.
What Is Square Footage?
Square footage measures area, or the amount of two-dimensional surface inside a boundary. It is commonly used for rooms, floors, patios, gardens, building plans, flooring, carpet, tile, and other projects where surface size matters.
One square foot is the area of a square that measures 1 foot by 1 foot. A room measuring 10 feet by 10 feet therefore contains 100 square feet, not 20 feet.
Feet and square feet measure different things. A foot is a unit of length. A square foot is a unit of area produced by multiplying one length by another.
How to Measure a Rectangular Room
Measure the room's length and width across the floor, using the same boundaries for each measurement. For a simple rectangular room, multiply those two dimensions to find the floor area.
For example, a room that measures 12 ft by 10 ft has an area of 120 ft². A room measuring 4 m by 3 m has an area of 12 m², which is about 129.17 ft².
Keep both dimensions in the same unit. If one measurement is 12 feet and another is 10 feet 6 inches, convert the 6 inches to 0.5 feet before entering 10.5 ft, or measure both dimensions entirely in inches.
| Dimensions | Square feet | Square metres |
|---|---|---|
| 8 × 10 ft | 80 ft² | 7.43 m² |
| 10 × 10 ft | 100 ft² | 9.29 m² |
| 10 × 12 ft | 120 ft² | 11.15 m² |
| 12 × 12 ft | 144 ft² | 13.38 m² |
| 12 × 15 ft | 180 ft² | 16.72 m² |
| 15 × 20 ft | 300 ft² | 27.87 m² |
| 20 × 20 ft | 400 ft² | 37.16 m² |
L-Shaped and Irregular Rooms
An L-shaped room does not need a special formula. Divide the floor into two or more rectangles, measure each rectangle separately, then add their areas.
Use Multiple rectangular areas to enter those sections directly. The sections should cover the measured space once without overlapping. Overlapping rectangles count the shared area twice and make the total too large.
The same method works for many hallways, open-plan spaces, extensions, alcoves, and irregular floor plans that can be broken into simple rectangular sections.
Calculating Several Rooms or an Entire Floor
To find the combined floor area of several rooms, calculate each room separately and add the results. The multiple-area mode performs that addition automatically and supports up to 50 rectangular sections.
This is useful when estimating the measured area of a bedroom, hallway, living room, kitchen, and other spaces together. It can also be used for a single irregular room divided into several rectangles.
Do not include the same section in two rows. If you are measuring a complete floor, decide which spaces belong in your total before measuring so shared boundaries, openings, or adjoining areas are handled consistently.
Circle and Triangle Areas
For a circle, the area depends on its radius. The radius runs from the centre to the edge, while the diameter runs from one edge to the opposite edge through the centre. The diameter is twice the radius.
If you know the diameter, choose Diameter in the calculator rather than dividing it manually. A circle with a radius of 5 ft has an area of about 78.54 ft².
For a triangle, enter the base and its perpendicular height. The perpendicular height forms a right angle with the base. A sloping side should not be used as the height unless it is also perpendicular to the chosen base.
Square Feet and Square Metres
One international foot is exactly 0.3048 metres. Squaring that relationship gives 1 square foot = 0.09290304 square metres.
The reverse conversion is approximately 1 square metre = 10.7639 square feet. The calculator performs the conversion after calculating the area, so you can enter either metric or US customary length measurements.
Area conversion factors are squared because area has two dimensions. Converting 1 foot to metres and converting 1 square foot to square metres are therefore different operations.
| Square feet | Square metres |
|---|---|
| 50 ft² | 4.65 m² |
| 100 ft² | 9.29 m² |
| 250 ft² | 23.23 m² |
| 500 ft² | 46.45 m² |
| 1,000 ft² | 92.90 m² |
| 1,500 ft² | 139.35 m² |
| 2,000 ft² | 185.81 m² |
Measured Area and Material Coverage
A room's measured area is a starting point for estimating materials such as flooring, carpet, tile, turf, or underlay. The exact calculated area is not always the same as the quantity that should be ordered.
Cuts, offcuts, damaged pieces, pattern alignment, plank direction, tile layout, room shape, and package sizes can increase the amount of material required.
Check the coverage and installation guidance for the specific product before ordering. A single waste percentage is not appropriate for every material or every layout.
Common Square Footage Mistakes
Mixing units: Multiplying a measurement in feet by another measurement in inches does not produce square feet. Convert both dimensions to the same unit first.
Adding lengths instead of multiplying: A 12 ft by 10 ft room is 120 ft². Adding 12 and 10 gives the perimeter-related value 22 ft, not the floor area.
Using diameter as radius: A circle's diameter is twice its radius. Entering a diameter as though it were a radius makes the calculated area four times too large.
Using a sloping side as triangle height: Triangle area uses the perpendicular distance from the base to the opposite vertex.
Overlapping sections: When an irregular floor is split into rectangles, each part of the floor should appear in only one section.
How This Calculator Works
The calculator first converts the entered length measurements to metres. Feet use the exact international conversion of 0.3048 m per foot, while inches, metres, and centimetres are converted to the same base unit.
It then applies the area formula for the selected shape. Rectangle and multiple-area modes multiply length by width, circle mode uses πr², and triangle mode multiplies the base by the perpendicular height and divides by two.
The calculated square metres are converted to square feet using 1 ft² = 0.09290304 m². Multiple-area mode calculates each rectangle independently before adding the results.
Square Footage Formulas
Use measurements in the same length unit before applying an area formula. The calculator handles unit conversion automatically.
- Area of one shape
- Rectangle length
- Rectangle width
- Circle radius
- Circle diameter
- Triangle base
- Perpendicular triangle height
- Area of one section in a multi-area calculation
- Number of measured sections
Examples
12 × 10 ft bedroom
Rectangle: 12 ft long × 10 ft wide
120 ft², or about 11.15 m².
12 × 12 ft room
Rectangle: 12 ft × 12 ft
144 ft², or about 13.38 m².
L-shaped room
Split the room into 12 × 10 ft and 6 × 5 ft rectangles.
120 ft² + 30 ft² = 150 ft².
The two rectangles should meet without overlapping.
Three-room total
120 ft² bedroom + 180 ft² living room + 80 ft² office
380 ft² total, or about 35.30 m².
Room measured in metres
Rectangle: 4 m × 3 m
12 m², or about 129.17 ft².
Circular patio
Circle with a radius of 5 ft
About 78.54 ft², or 7.30 m².
Triangular section
Base 10 ft × perpendicular height 6 ft
30 ft², or about 2.79 m².
Frequently Asked Questions
How do I calculate square footage?
For a rectangle, multiply the length by the width after expressing both measurements in the same unit. A 12 ft by 10 ft room is 120 ft².
How many square feet is a 10 × 10 room?
A rectangular room measuring 10 ft by 10 ft has an area of 100 square feet.
How many square feet is a 12 × 12 room?
A 12 ft by 12 ft room contains 144 square feet.
How many square feet is a 12 × 15 room?
Multiply 12 by 15. The floor area is 180 square feet.
How do I calculate an L-shaped room?
Divide the room into two or more nonoverlapping rectangles, calculate the area of each rectangle, then add them together. Multiple rectangular areas mode can do this in one calculation.
Can I calculate several rooms at once?
Yes. Choose Multiple rectangular areas and add one row for each room or rectangular section. The calculator supports up to 50 areas and shows both the individual areas and combined total.
Can I enter measurements in metres or centimetres?
Yes. Select metres or centimetres as the length unit. The result is still shown in both square metres and square feet.
Can I enter measurements in inches?
Yes. Select Inches and enter both dimensions in inches. The calculator converts the measurements before returning the area in ft² and m².
What is the difference between feet and square feet?
Feet measure one-dimensional length. Square feet measure two-dimensional area. A line can be 10 feet long, while a 10 ft by 10 ft floor covers 100 square feet.
How many square feet are in one square metre?
One square metre is approximately 10.7639 square feet.
How many square metres are in one square foot?
One square foot is exactly 0.09290304 square metres based on the international foot definition.
How many square feet are in an acre?
One acre contains exactly 43,560 square feet. An acre is a unit of area and does not have to be square.
Should I enter the radius or diameter of a circle?
Choose whichever measurement you have. Radius is the distance from the centre to the edge. Diameter is the full distance across the circle through its centre and equals twice the radius.
Which height should I use for a triangle?
Use the perpendicular height from the chosen base to the opposite vertex. Do not use a sloping side unless it is perpendicular to the base.
Does room height affect square footage?
Not when calculating ordinary floor area. Length and width determine the two-dimensional area. Ceiling height becomes relevant when calculating volume and can also matter under particular property-measurement standards.
Is this the same as the official square footage of a house?
Not necessarily. This calculator finds geometric area from the dimensions you enter. Property listings, appraisals, building records, and legal documents may follow specific rules about which finished or unfinished areas are included and how a building must be measured.
How much flooring should I buy?
Use the measured floor area as the starting quantity, then check the product and installation guidance. Extra material may be needed for cuts, patterns, waste, damaged pieces, or irregular layouts.