Square Footage Calculator

What square footage means

Square footage is simply area expressed in square feet: the number of one-foot by one-foot squares that fit on a floor. Builders, flooring suppliers and estate agents all start from it, which is why a quick, accurate figure is useful before you order anything.

This calculator works for any length unit (millimetres, centimetres, decimetres, metres, inches, feet or yards). The result is shown in the unit you pick in the Metric menu, so choosing metres gives square metres and choosing feet gives square feet.

How to use the calculator

1. Choose the room shape: a simple rectangle, or a compound shape made of two rectangles.
2. Choose the Metric (the unit for the answer). Every measurement below has its own unit menu, so you can mix units freely, for example centimetres for a width and metres for a length.
3. Enter the width and length. For a compound shape, enter the first section and then the width and length of the second section.
4. Optionally enter a price per unit square. It must be in the same unit as the Metric menu: a price of $10 per square foot goes with feet selected.
5. Press Calculate square feet to see the area and, if you gave a price, the total cost.

Leaving a field empty counts as zero. If nothing is entered for the first section, no result is shown.

Area of a rectangular room

area = width × length

Measure the two sides along the floor at their longest points, in the same unit, and multiply. A living room that is 15.5 ft by 11.25 ft has an area of 15.5 × 11.25 = 174.375 ft².

Different units are handled automatically. A room that is 350 cm wide and 4.2 m long is 3.5 m × 4.2 m = 14.70 m², which is the same as 158.23 ft².

Rooms with a more complex shape

L-shaped, T-shaped and similar rooms are just rectangles joined together. Divide the floor plan into non-overlapping rectangles, find the area of each and add them up.

total area = (width₁ × length₁) + (width₂ × length₂)

Example: an open-plan room has a main space of 12 ft by 15 ft and a dining alcove of 6 ft by 8 ft. The areas are 180 ft² and 48 ft², so the total is 228 ft².

The same room can also be seen as a large rectangle with a corner missing. If the bounding rectangle is 20 ft by 14 ft (280 ft²) and the notch is 8 ft by 6 ft, the floor is 280 − 48 = 232 ft². Either route works, so pick whichever needs fewer measurements.

The compound option handles two sections. For a shape with three or more parts, run the calculator for the first two, then add the remaining rectangles by hand or with the area calculator.

Square units and how they relate

A square foot is 144 square inches, and a square yard is 9 square feet. To convert an existing figure, use the area converter or the dedicated square meters to square feet converter.

From square footage to a project price

Flooring, carpet, vinyl, underlay, paint and many floor finishes are priced per square unit, so multiplying the area by that price gives a first estimate.

cost = area × price per square unit

For the 228 ft² room above and a finish that costs $3.75 per square foot, the cost is 228 × 3.75 = $855.

Real orders are larger than the floor area. Add 5 to 10% for cuts and breakage on simple layouts, and more for diagonal patterns. If the finish is sold in boxes of tiles, the tile calculator rounds up to whole boxes, and the paint calculator covers walls, which depend on height as well as floor size.

Measuring tips and common pitfalls

• Measure at floor level and at the widest points, because walls are rarely perfectly square.
• Keep one unit per measurement. If a tape gives feet and inches, convert inches to a decimal: 11 ft 3 in is 11.25 ft.
• Subtract fixed obstacles such as a built-in kitchen island only if the finish will not run underneath them.
• Do not confuse the area you walk on with the area quoted in a property listing. Listings often follow rules about what counts as living space (garages, unfinished basements and stairwells are commonly treated differently), so the number can differ from a simple floor measurement.