Square Feet Calculator for Rooms, Plots and Walls
Square feet = length × breadth, both in feet. Convert inches first: divide by 12, so 12 ft 6 in = 12.5 ft.
A 12 ft 6 in × 10 ft 9 in room is 12.5 × 10.75 = 134.375 sq ft, about 12.48 m². Add more rooms below, or switch to wall area.
Calculate room, plot or wall area
Changing a dimension unit clears its measurements for re-entry. Feet and inches are separate: enter 12 and 6 for 12 ft 6 in. In wall mode, enter opening areas in square units, not door widths.
- Total area
- 134.375 sq ft
- Square metres
- 12.4839 m²
- Square yards / gaj
- 14.9306 sq yd
- Acres
- 0.00308483 acres
Metric results use 1 m² ≈ 10.7639 sq ft. No wastage or loading added. Add each surface once; do not overlap rectangles.
For floor finishes, continue to the tile calculator.
Area formulas for building work
Split any floor or plot into rectangles, triangles and circles, work out each one, then add them.
| Shape | Formula | Example in feet |
|---|---|---|
| Rectangle | Length × breadth | 12.5 × 10.75 = 134.375 sq ft |
| L-shape | Rectangle A + rectangle B, no overlap | 12 × 8 + 6 × 4 = 120 sq ft |
| Triangle | Base × perpendicular height ÷ 2 | 20 × 15 ÷ 2 = 150 sq ft |
| Circle | π × radius² | Radius 7 ft: 49π ≈ 153.938 sq ft |
| Walls | Perimeter × height − doors − windows | 46.5 × 10 − 21 − 16 = 428 sq ft |
For a triangle, use the height at right angles to the base, not the sloping side. For a circle, halve the measured diameter. For an irregular plot, measure a diagonal too and work it as triangles: the four side lengths alone don't fix its area.
Worked example: room floor and four walls
A 12 ft 6 in × 10 ft 9 in room with 10 ft walls has 134.375 sq ft of floor and 428 sq ft of wall after one door and one window.
- Length: 12 + 6 ÷ 12 = 12.5 ft. Breadth: 10 + 9 ÷ 12 = 10.75 ft.
- Floor: 12.5 × 10.75 = 134.375 sq ft, about 12.484 m² or 14.931 sq yd.
- Inside perimeter: 2 × (12.5 + 10.75) = 46.5 ft. At 10 ft height, gross wall area = 465 sq ft.
- One 3 × 7 ft door = 21 sq ft; one 4 × 4 ft window = 16 sq ft. Net walls = 465 − 21 − 16 = 428 sq ft.
Take the floor figure to the tile calculator and the wall figure to the plaster calculator or paint calculator. Add the ceiling separately if it is painted. Reveals, soffits and billing deductions for openings follow the work specification.
A second room of 10 × 8 ft adds 80 sq ft, for a total of 214.375 sq ft. A 30 × 40 ft plot is 1,200 sq ft = 133⅓ sq yd (gaj) ≈ 111.484 m² ≈ 0.027548 acre.
Square feet, m², gaj and acres
1 m² = 10.7639 sq ft, 1 sq yd (gaj) = 9 sq ft and 1 acre = 43,560 sq ft.
- m² to sq ft: multiply by 10.7639. Sq ft to m²: divide by 10.7639.
- Sq ft to gaj: divide by 9. In plot sales, gaj means square yard, so 100 gaj = 900 sq ft.
- 1 acre = 43,560 sq ft = 4,840 sq yd.
- 1 m = 1,000 mm, so 1 m² = 1,000,000 mm². A 3,000 × 4,000 mm room is 12 m² ≈ 129.1668 sq ft.
Conversion basis: NIST SI conversion tables and NIST international-foot area definitions. The exact factor is 10.76391…; the calculator uses 10.7639, as our plaster calculator does, and rounds only the displayed result. Sources checked 21 October 2026.
Carpet, built-up and super built-up area
Carpet area is the usable floor inside the flat, built-up area usually adds the walls, and super built-up adds a share of common areas. No fixed percentage converts one into another.
Carpet area: Section 2(k) of the Real Estate (Regulation and Development) Act, 2016 defines it as the net usable floor area of an apartment. It includes the internal partition walls and excludes external walls, service shafts, exclusive balconies or verandahs and exclusive open terraces.
Built-up area: usually carpet area plus wall thickness and other covered areas such as balconies. What it includes varies, so check the drawing or agreement.
Super built-up area: built-up area plus an allotted share of common areas such as lobbies and stairs. Ask the builder for the area statement; don't add a guessed percentage to a room total.
For tiles, paint or plaster, measure the surface that gets the finish. For a flat purchase, check the agreement's carpet area against the RERA definition above.
Square feet calculator FAQ
How do I calculate square feet from feet and inches?
Turn each measurement into feet first (feet + inches ÷ 12), then multiply length by breadth. A 12 ft 6 in × 10 ft 9 in room is 12.5 × 10.75 = 134.375 sq ft. Don't type 12.6 for 12 ft 6 in; it is 12.5 ft.
How many square feet are in one square metre, gaj or acre?
1 m² = 10.7639 sq ft (rounded). 1 square yard = 9 sq ft, and in plot sales 1 gaj means 1 square yard, so a 100 gaj plot is 900 sq ft. 1 acre = 43,560 sq ft.
How do I add several rooms or an L-shaped floor?
Add one row per room, pick its shape and unit, and read the total. Split an L-shaped room into two rectangles that don't overlap: 12 × 8 ft plus 6 × 4 ft is 96 + 24 = 120 sq ft.
Can I use floor area to order plaster or paint?
No, use wall area: total wall length × height, less the door and window openings. For a 12 ft 6 in × 10 ft 9 in room with 10 ft walls, 46.5 × 10 − 21 sq ft door − 16 sq ft window = 428 sq ft. Measure the ceiling and reveals separately.
Is the sum of room areas the RERA carpet area?
No. Rooms measured wall to wall leave out the internal partition walls, which RERA carpet area includes. Carpet area also excludes external walls, service shafts, exclusive balconies or verandahs and exclusive open terraces, so leave those out of the total.
Does this calculator add tile wastage or built-up loading?
No. It gives the measured area only. The tile calculator adds the wastage allowance. No built-up or super built-up loading is added either.
Need item-wise quantities for a whole house or building? Send the drawings for a BOQ from your drawings.