gizmobench

Square Footage Calculator

Add each room as a line, typing the sides the way you measured them, and read the floor in square feet, square metres, square yards and acres at once. Six shapes cover the awkward rooms: rectangle, square, circle from its diameter, triangle, L-shape and trapezoid, with the shape drawn and labelled above the total. A cost per square foot turns the area into a price to the cent.

lengthwidth
Square footage · Rectangle · length × width0sq ftType the sides to start: 12' 6", 12 ft 6 in, 12.5 or 3.8 m
Shape
Length
Width
Unit
Name
Cost per sq ft

Type each side the way you measured it: 12' 6", 12'-6", 12 ft 6 in or 12.5 in feet; 3.4 or 340 cm in metres. A written unit always wins over the switch. The total counts the shape above plus every room in the list, so a single room never needs adding; Add room moves it to the list and clears the sides for the next one.

A floor is a list of rooms. An awkward room is an L-shape, or two rectangles added as two lines, and a whole floor is every room down the list. Areas are exact for the shapes and dimensions you give, and conversions use the international foot (0.3048 m) and the acre (43,560 square feet). Real rooms have alcoves and angles the shapes do not know about.

Common questions

How do I type feet and inches?
The way you would write them down. 12' 6", 12'6, 12'-6" as a plan draws it, 12 ft 6 in and 12.5 all read as twelve and a half feet, and 6" on its own is half a foot. For metric, set the unit switch to m and type 3.4, or write the unit yourself: 340 cm, 3.4 m or 3400 mm. A unit you write always wins over the switch, so 12 ft in metric mode is still twelve feet.
How do I add up several rooms?
Type the first room's sides and its area shows straight away; the total already counts the shape you are typing, so a single room never needs an Add click. Press Add room to move it into the list, where it keeps its name, its shape and its sides, and the fields clear for the next one. The total is every room in the list plus whatever is in the fields. Remove takes a room back out, and the list is remembered in your browser between visits.
How do I get the area of a circle from its diameter?
Pick Circle and type the distance across. The area is pi times the square of half the diameter, so a bay window 10 feet across is 78.54 square feet. Measure the diameter rather than the radius, because that is the measurement a tape actually gives you.
How many square feet are in an acre?
43,560. Acres are the total in square feet divided by 43,560, so a 200 by 150 foot lot is 30,000 square feet and 0.689 acres. The acreage page of this tool puts acres on the top line and lists square feet, square metres, square yards and hectares underneath.
How does the cost estimate work?
Type a price per square foot and the cost line multiplies it by the total, rounded to the cent. It is the material or the rate times the area and nothing else: no tax, no labour, no allowance for waste or off-cuts, which flooring is usually bought with. Leave the field empty and no cost line is shown.
What about a room that is not a simple shape?
An L-shaped room is one line: pick L-shape and type the two rectangles that make it. A room with an alcove or a bay is two lines, the main rectangle and the extra piece, added separately. Any floor plan breaks into rectangles, triangles and trapezoids, and the total is the sum of the pieces.

Areas are exact for the shapes and dimensions you give, and conversions use the international foot (0.3048 m) and the acre (43,560 square feet). Real rooms have alcoves and angles the shapes do not know about.