Room Area Calculator
(Square Feet, Square Metres and Square Yards)
Enter your room's dimensions to find its area in square feet, square metres and square yards. Works for rectangles, L-shapes, circles and triangles.
Shape
Measured in
Result
💡 Formula Guide
How to Calculate the Area of a Room
The area of a room is the amount of floor it covers, found by multiplying length by width for a rectangle and by splitting other shapes into simple parts. People search for a room area calculator when they are pricing flooring, checking whether furniture will fit, comparing rentals or planning a paint job. The arithmetic is simple, but mixing feet and metres, or forgetting a corner of an L-shaped room, is where most mistakes appear. This tool handles the shape and the conversions for you.
A room 14 ft by 12 ft covers 168 square feet. In metric that is about 15.6 square metres, because one square metre is roughly 10.764 square feet, and about 18.7 square yards, since a square yard is exactly 9 square feet.
Formulas for Common Shapes
| Shape | Formula | Example |
|---|---|---|
| Rectangle or square | Length × Width | 14 × 12 ft = 168 sq ft |
| L-shape | Full Length × Width − Missing Corner | 14 × 12 − 5 × 4 = 148 sq ft |
| Circle | π × (Diameter ÷ 2)² | 10 ft across = 78.5 sq ft |
| Triangle | ½ × Base × Height | Base 12 ft, height 8 ft = 48 sq ft |
Irregular rooms are best handled by dividing them into rectangles and triangles, calculating each and adding the results. Draw a rough sketch, label each dimension as you measure and check that the pieces add up to the overall size. If two walls meet at an angle other than 90 degrees, split the space into a rectangle plus a triangle rather than assuming a square corner.
Units and Conversions
Measure everything in the same unit before multiplying. If you take one dimension in feet and the other in inches, convert first: 12 ft 6 in is 12.5 ft. The calculator converts from feet, metres, inches, centimetres and yards using exact factors (1 foot is 0.3048 metres, 1 yard is 0.9144 metres) and shows the result in square feet, square metres and square yards together, so you can compare a UK or European floor plan with a US product listing.
💡 Tip: when converting area, remember to square the factor. Multiplying square metres by 3.281 gives the wrong answer; the correct factor for area is 10.764, which is 3.281 squared.
Measuring Well
- Measure the floor, not the wall face. Take dimensions at floor level along the widest points, and measure twice.
- Ignore skirting boards for flooring estimates, but include closets and alcoves that will be covered.
- Split the room into simple shapes and add the areas, especially around bay windows, chimney breasts and stairwells.
- Add a waste allowance when ordering materials, since cuts and offcuts are unavoidable.
Listed areas in property advertisements can use different definitions, such as gross internal or carpet area, so a single-room measurement may not match. Use the numbers here for planning work in one room, not for comparing property listings.
What to Do With the Area
Once you know the floor area, the next steps depend on the project. For flooring, multiply by the price per square foot and add a waste allowance, or use the Tile & Flooring Calculator to convert area into tiles and boxes. For painting, wall area matters more than floor area, so use the Paint Coverage Calculator, and for wall coverings try the Wallpaper Coverage Calculator. Lighting is planned from floor area too, which is what the Recessed Lighting Calculator uses to decide how many lights a room needs.
Keep your measurements and sketch. Every later calculation, from flooring to lighting to heating, starts from the same numbers, and re-measuring a room is more work than saving the figures once.
Frequently Asked Questions About Room Area
How do you calculate the square footage of a room?
Measure the length and width in feet and multiply them. A room 14 ft long and 12 ft wide is 14 × 12 = 168 square feet. For a room measured in metres, multiply in metres to get square metres and multiply by 10.764 to convert to square feet.
How do I find the area of an L-shaped room?
Either split it into two rectangles and add them, or measure the full outer rectangle and subtract the missing corner. A 14 × 12 ft outline with a 5 × 4 ft corner missing is 168 − 20 = 148 square feet. The calculator's L-shaped option uses the subtraction method.
How many square feet are in a square metre?
One square metre is about 10.764 square feet, because one metre is about 3.281 feet and the area is that number squared. One square yard is 9 square feet, or about 0.836 square metres.
How do I measure a room with alcoves or bay windows?
Treat each part as its own rectangle or shape, calculate each area and add them. Measure floor to floor at the widest points, not along the skirting board at an angle, and round measurements to the nearest inch or centimetre.
What is the area of a circular room or table?
π × (diameter ÷ 2)². A circle 10 ft across has an area of about 78.5 square feet. The circumference, or perimeter, is π × diameter, about 31.4 ft for the same circle.
Do I measure inside or outside the walls?
For flooring, paint or furniture, measure the inside floor area you will actually cover. For a total floor plan that includes wall thickness, outside measurements are larger. Property listings can use different definitions of area, so a single-room measurement may not match a listed figure.
How can I use the room area for flooring or paint?
Flooring, carpet and tile are priced by area, so multiply the room area by the price per square foot and add a waste allowance. Paint and wallpaper depend on wall area rather than floor area, so use the dedicated calculators, which also deduct doors and windows.
How accurate is a room area estimate?
It is only as accurate as your measurements. Use a tape or laser measure, measure each dimension twice and remember that few rooms are perfectly square. For flooring orders, add a waste allowance on top of the measured area.
Last Updated: September 2026 | Uses standard geometry and exact unit conversions (1 ft = 0.3048 m). Real rooms are rarely perfect, so treat results as estimates from your measurements.