Square Footage Calculator — Area of a Room
Add up the square feet, metres, yards and acres of one or more rooms — rectangles, circles, triangles, L-shapes and more — with an optional total cost.
- = 120 ft²
Total area, room by room
Enter the length and width of each room or area — or pick another shape for a row — and the tool sums them into total square feet, square metres, square yards and acres. Add as many areas as you like. Enter a price per square unit to also get a total cost for flooring, carpet or tiling. An optional “Waste allowance %” box adds what to buy on top of what was measured — the ft² and m² with that allowance on, and the cost with it when a price is set — while the measured totals stay as measured, and a hint under the box gives the trade's usual allowance. Print opens the browser's print dialog, which can also save a PDF: the room list with every measurement and its working, the totals and the drawing.
Feet or metres
Switch the unit — feet, inches, yards, metres, centimetres or millimetres — and enter measurements in it; the ft², m², yd² and acre totals are always shown. Everything is calculated in your browser — nothing is uploaded.
Rooms that are not rectangles
Each row has a Shape select — rectangle, circle, triangle, trapezoid, ellipse, sector (pie slice) or L-shape — whose boxes change to the measurements that shape takes, with its formula printed beside them, and rows of different shapes add into one total, which is how every awkward room is measured in practice. An L-shape is its overall length and width minus the cut-out corner, so it needs no splitting by hand. A room with a chimney breast is the room minus a small rectangle; measure the remaining strips as rectangles instead. For a bay, give it a trapezoid row of its own, or take the widest and deepest points and accept that you have overestimated slightly, which is what you want when buying material.
Feet and metres do not convert the way lengths do
One metre is 3.28 feet, so it is tempting to reach for 3.28 when converting an area. It is wrong: area converts by the square, and one square metre is 3.28² = 10.764 square feet. Getting this backwards is a common error in flooring quotes, and it is out by more than a factor of three. The tool converts both ways so you never have to, and the price has a unit of its own: the select beside it offers ft², yd² and m², so a room measured in metres can still be priced per square foot. It starts on square feet when you measure in feet, inches or yards and on square metres when you measure in metres, centimetres or millimetres, and the price’s label names the unit in use.
Frequently asked questions
How do I calculate square footage?
Multiply length by width for each rectangular area and add them up. For odd shapes, pick the shape for that row or split it into rectangles — this tool sums multiple areas for you.
How do I convert square feet to square metres?
Divide square feet by 10.764. The tool shows both totals at once, so you don’t need to convert by hand.
My room is L-shaped. How do I measure it?
Pick "L-shape" for the row and enter the overall length and width and the length and width of the cut-out corner, or split it into rectangles and add a row for each. Any shape made of straight walls at right angles can be cut into rectangles, and their areas add up to the whole.
Why is one square metre not 3.28 square feet?
Because area scales by the square of the length factor. One metre is 3.28 feet, so one square metre is 3.28 × 3.28 = 10.764 square feet. Using 3.28 for an area underestimates it by more than three times.
What unit should the price be in?
Whichever unit your quote is in. The select beside the price box offers ft², yd² and m², so a price per square foot can cost a room measured in metres, and the other way round. It starts on square feet when you measure in feet, inches or yards and on square metres when you measure in metres, centimetres or millimetres, and the price box’s label names the unit in use.
Can it give the total in square yards or acres?
Yes. "Total yd²" and "Total acres" sit beside "Total ft²" and "Total m²" whatever unit you measured in, and an area under an acre keeps enough digits that a single room does not read as zero. Measurements can be in feet, inches, yards, metres, centimetres or millimetres.
Can I enter identical rooms once, and check the arithmetic?
Yes. Each row has a “How many” box after its measurements, so four identical bedrooms are one row, and each row prints its own working beside its boxes — its area, or the quantity times the area and the subtotal. Under the totals, every valid area is drawn side by side at one scale and numbered as in the list, so a mistyped measurement shows up as a shape out of proportion; when the sizes are too far apart for one scale the drawing is left out. The areas are not arranged as a floor plan, because their positions were never measured.
How much extra flooring should I buy?
Type a percentage into “Waste allowance %” beside the price. The measured totals stay as they are, and two more figures show the ft² and m² to buy with that allowance on — plus the cost with it, when a price is set. The hint under the box gives the usual trade allowance for flooring and tile, with more for diagonal layouts or awkward rooms.