Square Footage Calculator — Calculate Area in Sq Ft | SoftZaR

What Is Square Footage?

Square footage is a measurement of area expressed in square feet (ft² or sq ft). One square foot equals the area of a square that is one foot long on each side — precisely 144 square inches or approximately 0.0929 square meters. Square footage is the standard unit of area measurement in the United States for real estate, construction, interior design, and landscaping. Understanding how to calculate square footage accurately is essential for home buying, renovation planning, flooring installation, painting estimates, and material ordering.

How to Calculate Square Footage

Rectangle or Square

Area = Length × Width

A room measuring 15 feet by 12 feet has an area of 180 square feet (15 × 12 = 180). If measurements include inches, convert to decimal feet first: 15 feet 6 inches = 15.5 feet.

Triangle

Area = ½ × Base × Height

A triangular section with a 10-foot base and 8-foot height has an area of 40 square feet (0.5 × 10 × 8 = 40).

Circle

Area = π × r²

A circular patio with a 6-foot radius has an area of approximately 113.1 square feet (3.14159 × 6² = 113.1).

Trapezoid

Area = ½ × (a + b) × h

Where a and b are the parallel sides and h is the height between them. A trapezoid with parallel sides of 8 and 12 feet and a height of 6 feet has an area of 60 square feet.

Calculating Square Footage for Common Projects

Flooring

Measure each room separately. For rectangular rooms, multiply length × width. For L-shaped rooms, divide into two rectangles and add the areas. Always add a waste factor: 5–10% for hardwood and laminate, 10–15% for tile. This accounts for cuts at walls, pattern matching, and replacement pieces for future repairs.

Painting

For walls, multiply length × height for each wall, then subtract doors (~21 sq ft each) and windows (~15 sq ft each). One gallon of paint covers 350–400 sq ft with one coat. For ceilings, calculate length × width of the room.

Landscaping

Measure the yard or garden bed dimensions. For mulch, topsoil, or gravel, you'll also need to multiply by the desired depth to get cubic footage (or use our Concrete Calculator for volume calculations).

Square Footage Conversion Table

From	To	Multiply By
Square feet	Square meters	0.0929
Square meters	Square feet	10.764
Square feet	Square yards	0.1111 (÷9)
Square feet	Acres	0.000023 (÷43,560)
Acres	Square feet	43,560
Square inches	Square feet	0.00694 (÷144)

Common Room Sizes

Room Type	Typical Size	Square Footage
Small bedroom	10×10 ft	100 sq ft
Standard bedroom	12×12 ft	144 sq ft
Master bedroom	14×16 ft	224 sq ft
Living room	12×18 ft	216 sq ft
Kitchen	10×12 ft	120 sq ft
Bathroom	5×8 ft	40 sq ft
1-car garage	12×20 ft	240 sq ft
2-car garage	20×24 ft	480 sq ft

Sources and References

National Institute of Standards and Technology (NIST). (2023). The International System of Units, 9th edition. NIST SP 330.
National Association of Home Builders. (2022). Typical Room Dimensions and Square Footage by Home Size. Housing Economics.
Residential Construction Standards, International Residential Code (IRC). (2021). ICC Digital Codes.

Frequently Asked Questions

How do I calculate square footage?

For a rectangle or square, multiply length × width. For example, a room that is 12 feet long and 10 feet wide is 120 square feet (12 × 10 = 120). If your measurements include inches, convert them to decimal feet first: divide inches by 12 and add to the feet measurement. So 12 feet 6 inches = 12.5 feet. For non-rectangular shapes, our calculator provides formulas for triangles, circles, and trapezoids.

How do I convert square feet to square meters?

Multiply square feet by 0.0929 to get square meters. For example, 500 sq ft × 0.0929 = 46.45 sq m. To convert square meters to square feet, multiply by 10.764. Our calculator provides automatic conversions between all common area units including square feet, square meters, square yards, and acres.

How do I calculate square footage for an irregularly shaped room?

Break the irregular shape into smaller regular shapes (rectangles, triangles, etc.). Calculate the area of each shape separately, then add them together. For example, an L-shaped room can be divided into two rectangles. A room with a bay window can be calculated as a rectangle plus a triangle or trapezoid. Use our multi-area feature to add multiple shapes and get the total automatically.

How much flooring do I need?

Calculate the total square footage of the area, then add 5–10% for waste (cutting, mistakes, and future repairs). For tile, add 10–15% because tiles must be cut at walls and transitions. For hardwood, add 5–10%. For carpet, rolls come in standard widths (12 or 15 feet), so calculate based on roll layout to minimize seams. Our calculator includes a waste factor to help you order the right amount.

What is the difference between square feet and linear feet?

Square feet measures area (two dimensions — length × width), while linear feet measures only length (one dimension). If you buy 100 linear feet of fencing, that's the total length. If you buy 100 square feet of flooring, that covers a 10×10 foot area. Materials like crown molding, baseboards, and gutters are sold by linear foot, while flooring, paint coverage, and roofing are sold by square foot.

How do I calculate wall square footage for painting?

Multiply the wall length × wall height to get the total wall area. For a room, add up all four walls, then subtract the area of doors (approximately 21 sq ft each for standard doors) and windows (approximately 15 sq ft each for standard windows). One gallon of paint typically covers 350–400 square feet with one coat. For two coats, double the area or halve the coverage per gallon.

Dimensions