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?

The current complete shape already contributes to the total. Add room moves it to the list and clears its sides for the next piece. The total includes all listed rooms plus the current complete shape. If a listed room is invalid or the current shape is partly entered, finish or clear it before copying a whole total. Remove takes a listed room out. Deliberately changed fields are stored in this browser; restoration does not rewrite saved work.

How do I get the area of a circle from its diameter?

Pick Circle and enter the diameter, the distance across the whole circle. Area is pi times the square of half the diameter: 10 feet across gives about 78.54 square feet. A partial circle or curved boundary requires a different model; the circle option does not calculate a circular segment.

How many square feet are in an acre?

One international acre is 43,560 square feet. Choose Known area, enter 43,560 and select sq ft to see one acre. Enter 1 and select acres for the reverse conversion. A measured rectangular 200 by 150 foot lot gives 30,000 square feet, about 0.689 acres. The acreage page puts acres first.

How does the cost estimate work?

A supplied price per square foot is multiplied by the area; the total is rounded to cents. This is arithmetic on your supplied rate, with no tax, labour, waste or off-cut allowance. Unsupported numeric scales or an unreadable rate stop the cost and whole-summary copy. Area-only unit values remain available when the area itself is complete. It does not estimate market value or split rent between people.

What about a room that is not a simple shape?

Use measured, non-overlapping supported pieces. An L-shape adds two rectangles. Triangle height must be perpendicular to its base; trapezoid height must be perpendicular to its parallel sides. Arbitrary four- or five-sided land cannot be determined from side lengths alone. Curved boundaries, holes and property boundaries need additional measurements or a different workflow; this tool does not extract them from maps, addresses or plans.

Does the ft/m switch convert the dimensions I typed?

It sets the unit of a bare number. Changing ft to m reinterprets a bare 12 as 12 metres. Written units override the switch: 12 ft remains 12 feet in either setting. In Known area, select the unit of the supplied number. Results use rounded browser-number arithmetic, not a survey or a legal floor-area standard.

Square Footage Calculator

Calculate a measured room, floor or parcel from six shapes: rectangle, square, circle by diameter, triangle by base and perpendicular height, L-shape as two non-overlapping rectangles, and trapezoid by parallel sides and perpendicular height. Add separate pieces to one total, or choose Known area to convert square feet, square inches, square metres, square yards, acres and hectares. An optional supplied price per square foot gives an area-times-rate estimate.

Square footage · Rectangle · length × width--sq ftType the sides to start: 12' 6", 12 ft 6 in, 12.5 or 3.8 m

Calculate from

Shape

Length

Width

Unit

Name

Cost per sq ft

Known area converts square feet, square inches, square metres, square yards, acres or hectares. In Shapes mode, 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. The ft/m switch sets the meaning of bare numbers, so changing it reinterprets those numbers. 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. Shape formulae use browser-number arithmetic and rounded displays, with the international foot (0.3048 m) and acre (43,560 square feet). Enter measured perpendicular heights and non-overlapping pieces; this does not determine legal property area.

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?: The current complete shape already contributes to the total. Add room moves it to the list and clears its sides for the next piece. The total includes all listed rooms plus the current complete shape. If a listed room is invalid or the current shape is partly entered, finish or clear it before copying a whole total. Remove takes a listed room out. Deliberately changed fields are stored in this browser; restoration does not rewrite saved work.
How do I get the area of a circle from its diameter?: Pick Circle and enter the diameter, the distance across the whole circle. Area is pi times the square of half the diameter: 10 feet across gives about 78.54 square feet. A partial circle or curved boundary requires a different model; the circle option does not calculate a circular segment.
How many square feet are in an acre?: One international acre is 43,560 square feet. Choose Known area, enter 43,560 and select sq ft to see one acre. Enter 1 and select acres for the reverse conversion. A measured rectangular 200 by 150 foot lot gives 30,000 square feet, about 0.689 acres. The acreage page puts acres first.
How does the cost estimate work?: A supplied price per square foot is multiplied by the area; the total is rounded to cents. This is arithmetic on your supplied rate, with no tax, labour, waste or off-cut allowance. Unsupported numeric scales or an unreadable rate stop the cost and whole-summary copy. Area-only unit values remain available when the area itself is complete. It does not estimate market value or split rent between people.
What about a room that is not a simple shape?: Use measured, non-overlapping supported pieces. An L-shape adds two rectangles. Triangle height must be perpendicular to its base; trapezoid height must be perpendicular to its parallel sides. Arbitrary four- or five-sided land cannot be determined from side lengths alone. Curved boundaries, holes and property boundaries need additional measurements or a different workflow; this tool does not extract them from maps, addresses or plans.
Does the ft/m switch convert the dimensions I typed?: It sets the unit of a bare number. Changing ft to m reinterprets a bare 12 as 12 metres. Written units override the switch: 12 ft remains 12 feet in either setting. In Known area, select the unit of the supplied number. Results use rounded browser-number arithmetic, not a survey or a legal floor-area standard.

Shape formulae use browser-number arithmetic and rounded displays, with the international foot (0.3048 m) and acre (43,560 square feet). Enter measured perpendicular heights and non-overlapping pieces; this does not determine legal property area.