Square Footage
Definition
Square footage (sq ft or ft²) is the measurement of area in imperial units, calculated by multiplying length × width in feet. It is the fundamental unit for pricing and estimating flooring, roofing, painting, siding, and almost every surface-related construction material. One square foot equals 144 square inches or approximately 0.0929 square meters. In real estate, square footage determines home value ($150–$400+/sq ft depending on market). In construction, material coverage rates are expressed per square foot — for example, a gallon of paint covers 350–400 sq ft.
Why is Square Footage Important?
For homeowners, contractors, and DIY builders across the United States, understanding Square Footage is essential to accurate material estimation and cost planning. Whether you are pouring a concrete driveway, framing a deck, or calculating roofing materials, mastering this concept helps prevent costly over-ordering or project delays from material shortages.
Our free construction calculators leverage this concept to provide instant, accurate estimates — saving hours of manual measurement and arithmetic while ensuring your project stays on budget.
What is Square Footage?
Square footage (sq ft or ft²) is the standard measurement of two-dimensional area in the US imperial system. One square foot equals a square measuring 12 inches × 12 inches (144 square inches). It is the fundamental unit for estimating, pricing, and ordering nearly every surface-related construction material — flooring, roofing, painting, siding, drywall, tile, and insulation.
How to Calculate Square Footage
Basic Formula: Square Feet = Length (ft) × Width (ft)
| Shape | Formula | Example |
|---|---|---|
| Rectangle | Length × Width | 20 ft × 15 ft = 300 sq ft |
| Triangle | ½ × Base × Height | ½ × 12 ft × 8 ft = 48 sq ft |
| Circle | π × Radius² | π × 10² = 314 sq ft |
| Trapezoid | ½ × (Base₁ + Base₂) × H | ½ × (10 + 14) × 8 = 96 sq ft |
| L-shaped room | Split into 2 rectangles | Add both areas together |
Square Footage Conversions
| From | To | Multiply By |
|---|---|---|
| Square Feet | Square Meters | × 0.0929 |
| Square Feet | Square Yards | ÷ 9 |
| Square Feet | Acres | ÷ 43,560 |
| Square Meters | Square Feet | × 10.764 |
| Square Inches | Square Feet | ÷ 144 |
Material Coverage per Square Foot
| Material | Coverage Rate | Avg Cost/sq ft (2024) |
|---|---|---|
| Interior paint | 350–400 sq ft/gallon | $0.15–$0.50 (material) |
| Exterior paint | 250–350 sq ft/gallon | $0.25–$0.75 (material) |
| Laminate flooring | 1 sq ft per piece varies | $1.50–$5.00 installed |
| Hardwood flooring | N/A (sold per sq ft) | $6–$15 installed |
| Ceramic tile | N/A (sold per sq ft) | $5–$15 installed |
| Asphalt shingles | 33.3 sq ft/bundle (3 per square) | $3–$7 installed |
| Drywall (4×8 sheet) | 32 sq ft per sheet | $1.50–$3.50 installed |
| Insulation (batt) | Varies by bag/roll | $0.50–$2.00 per sq ft |
Square Footage in Real Estate
In residential real estate, square footage is the single most important factor in determining home value. The price per square foot metric allows comparison between properties of different sizes in the same market:
- National US average (2024): ~$150–$200/sq ft for existing homes
- New construction: $150–$400+/sq ft depending on market and finish level
- How it's measured: ANSI Z765 standard — includes all finished, heated/cooled living space. Excludes garages, unfinished basements, patios, porches, and areas with ceiling height below 5 feet
- Above-grade only: Most MLS listings count only above-grade square footage. Finished basement area is listed separately