Rectangle Square Footage Calculator
Enter your measurements below to get the area of a rectangle in square feet, square metres, square yards and acres. The live preview draws the rectangle to scale as you type, labelled on a measured grid, and you can drag its handles to change the measurements.
Area = Width × Length
Live scale preview
The shape is drawn to scale and relabelled as you type.
An example to start from. Drag a handle or type a measurement and it becomes yours.
Worked example
A rectangle with width 12 ft, length 15 ft works out at 180 square feet.
| Unit | Area |
|---|---|
| sq ft | 180 |
| m² | 16.72 |
| sq yd | 20 |
| sq in | 25,920 |
| acres | 0.004132 |
When to use the rectangle calculator
The rectangle is the shape almost every measuring job starts with. Bedrooms, living rooms, walls, decks, driveways, standard building lots and the majority of tiled floors are all rectangles, and every more complicated shape on this site is ultimately measured by breaking it into rectangles and adding or subtracting them.
Measuring a rectangular room accurately
Measure at floor level rather than at counter or window height — skirting boards, radiators and cabinet plinths all sit at the level where the flooring actually goes. Take the width at both ends of the room and the length down both sides. In a modern build the pairs will match; in an older house they often differ by an inch or two, and the smaller of the two readings is the one to use, because material has to fit the narrowest point.
Enter feet and inches as they read. The calculator gives every measurement its own feet box and inches box, and the inches box takes fractions, so a wall reading 12 ft 6 1/2 in goes in as 12 and 6 1/2. Working by hand, you would divide the inches by 12 first — 12 ft 6 in is 12.5 ft — because mixing feet and inches inside one multiplication is the single most common source of a wrong square footage figure.
What to include and what to subtract
For flooring, subtract anything permanently fixed to the subfloor that you will not lay under — a run of base cabinets, an island with a plinth — but keep closets and the area under free-standing appliances in the total. For a property figure, closets count and furniture is irrelevant.
If the room has an alcove or a chimney breast, measure the main rectangle first and then add or subtract the smaller rectangle. For a room with a corner missing, the L-shape calculator does the subtraction for you, and the multi-room calculator keeps a running total across a whole house. For measuring a room step by step — floor level, awkward shapes and what to include — see the guide to calculating the square footage of a room.
Frequently asked questions
How do I calculate the square footage of a rectangular room?
Multiply the width by the length, both in feet. A room 12 ft by 15 ft is 180 square feet. Measure at floor level and take the width at both ends of the room in case the walls are not parallel. Leftover inches go straight into the inches box — there is no need to convert them to a decimal first.
Does it matter which side I call the length?
No. Multiplication does not care about the order, so 12 × 15 and 15 × 12 both give 180 square feet. The labels only matter when you are ordering material that runs in one direction — carpet, planks, or patterned tile — because the roll or plank width has to be laid along a specific side.
Should I subtract closets, islands and built-ins?
It depends on what the number is for. For flooring or tile, subtract anything permanently fixed to the floor, such as a kitchen island or a built-in cabinet run, but include closets you are flooring through. For a property listing, closets count and free-standing furniture is irrelevant. For paint, you are measuring walls rather than floor, which is a different calculation entirely.
Other shapes
A space that is not a rectangle can nearly always be split into two or three of these and added together.
- Circle calculator
- L-Shaped Room calculator
- Parallelogram calculator
- Circle Sector calculator
- Square calculator
- Trapezoid calculator
- Triangle calculator
- Triangle (Three Sides) calculator
To add several spaces into one figure, use the multi-room square footage calculator. To turn this area into an order quantity, see the material calculators.
New to the math? The square footage formula for every shape explains the calculation behind each of these tools.