AREA
SURFACE AREA
FLOOR AREA
CARPET AREA

COMMON ACRONYMS
A, SQM, SFT, GLA, GFA, BUA

COMMON STANDARDS OF PRACTICE

1. V. Garga, R. Townsend, and D. Hansen, "A Method for Determining the Surface Area of Quarried Rocks," Geotechnical Testing Journal 14, no. 1 (1991): 35-45.
2. General Conference on Weights and Measures, The International Bureau of Weights and Measures

DEFINITION
Area: It is the amount of space within the perimeter of a 2 dimensional space, or is the two-dimensional space taken up by an object. The two domensional space may have unlimited number of sides or curves, such as in a triangle or a square or a circle or a pentagon, or may have irregular shapes which do not have equal sides or equal angles. Area of irregular shapes is acquired by dividing the shape into two or more regular shapes such as multiple squares, triangles, or other quadrilaterals.

Surface Area: It is the total area of the surface of a three-dimensional object. For example the the surface area of a cube is the area of all 6 faces added together. Surface area of a polyhedron, such as a cone, sphere, torus, or a prism can be also found by using well known formulae, or by creating a geometric net by unfolding the faces of the polyhedron. Finding surface areas of irregular three dimensional objects, like random rocks from a quarry, requires special tools, calculus and/ or experimental methods.

Net Usable Area/ Carpet area: It is that area in a house, which you could cover using a carpet. It is the net usable area of the apartment. This means it does not include the area covered by inner walls or outer walls. Carpet area of an apartment = Area of (bedrooms + living rooms + balconies + toilets + Staircases if within the house + Stores + kitchens) – (the thickness of the inner/ outer walls).

Built-up Area: It is the carpet area plus the area covered by walls. It includes balconies, terraces (with or without roof), mezzanine floors and other detachable habitable areas such as servant rooms, etc. Walls which are shared with other units are factored in at 50 per cent while other walls are computed fully. Areas which are common such as stairwells in the apartment building, elevator shafts/ lobbies etc are not included. Carpet area is generaly 70% of the Built up area where masonry walls are used. Built up area is 10-15 per cent more than the carpet area in wooden construction.

Super Built-Up Area (BUA): It is the built up area of an apartment plus the proprtionate share of common areas, such as hallways, pool, gym, elevator shafts/ lobbies, fire escape stairs, etc.

Gross floor area (GFA): The total floor area contained within the building measured to the external face of the external walls, including, sum of all floor areas, including basements, mezzanine and intermediate-floored tiers, and penthouses with headroom height of 7.5 ft (2.2 meters) or greater.

Gross internal area (GIA): The floor area contained within the building measured to the internal face of the external walls.

Gross leasable area (GLA): It is the amount of floor space available to be rented in a commercial property, including all internal/ external walls, including any basements, mezzanines, or upper floors.

WHY
Area is a measure of how much space there is inside a shape or on the surface of a body. Perimeter and area are two important and fundamental mathematical topics. They help to quantify physical space and also provide a foundation for more advanced mathematics found in algebra, trigonometry, and calculus.

WHEN
Calculating the area of a shape or surface is useful in everyday life; for example to calculate how much paint should be purchased to cover a wall, how many tiles should be purchased to finish a floor, how much grass seed you need to sow a lawn, much cloth to buy to stich a curtian, or how much rent to pay for an apartment.

HOW
Common formula for calculating areas of polygons are give below;

1. Circle: A = π r²
   where "r" is the radius of circle and "π" is the ratio of the circumference of any circle to the diameter of that circle and equals 3.14159265359
2. Triangle: A = ½ B h = √ (s [(s-a) (s-b) (s-c)]
   where "B" is the length of the base, and "h" is the length of the altitude of the triangle. In geometry, an altitude of a triangle is a line segment through a vertex and perpendicular to (i.e., forming a right angle with) a line containing the base (the side opposite the vertex). The length of the altitude, often simply called "the altitude", is the distance between the extended base and the vertex. There are many more ways/ formulae to find the area of a triangle depending on how much information is available about the angles and/or lengths of sides. In the second formula known as heron's formula, "s" is the semi-perimter of the triangle which equals to (a + b + c)/2, and "a", "b", and "c" are the lengths of 3 sides of the triangle.
3. Square: A = s²
   where "s" is the length of one of the sides
4. Rectangle: A = l w
   where "l" is the length (or height) of the rectangle and "w" is the width (or breadth) of the rectangle.
5. Parallelogram: A = B h
   where where "B" is the length of the base and "h" is the length of the altitude of the parallelogram. The area of a parallelogram is the sum of two triangles of equal area.
6. Ellipse: A = π x y
   where "x" is the semi-major axis (major semiaxis) or the longest semidiameter or one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter. "y" is the semi-minor axis (minor semiaxis) of an ellipse that is at right angles with the semi-major axis and runs to the perimeter. "π" is the ratio of the circumference of any circle to the diameter of that circle and equals 3.14159265359
7. Curve: A = ∫^a_b   f(x) dx
   where "A" is the area between a positive-valued curve and the horizontal axis, measured between two values "a" and "b" (b is defined as the larger of the two values) on the horizontal axis, and "f(x)" is the function that represents the curve.

Common formula for calculating areas of polyhedrons are give below;

1. Sphere: A = 4 π r² = π d²
   where "r" is the radius and "d" is the diameter
2. Cube: A = 6 s²
   where "s" is the side of the cube
3. Cuboid: A = 2 (l w + l h + w h)
   where "l" is the length, "h" is the height, and "w" is the width.
4. Prism: A = 2 B + P h
   where "B" is the area of one base, "P" is the perimeter of one base, "h" is the height
5. Cylinder (closed): A = 2 π r² + 2 π r h = 2 π r (r + h)
   where "r" is the radius of the circular base, h is the height of the cylinder
6. Pyramid: A = B + (P L / 2)
   where "B"is the area of base, "P" is the perimeter of base, "L" is the slant height

EXAMPLES