Square Footage Calculator

How to Calculate Square Footage

Square footage is one of the most fundamental measurements in construction, landscaping, and real estate. Whether you're planning to tile a floor, paint a room, mulch a garden, or estimate flooring costs, knowing the exact square footage is essential. This calculator helps you find the area of virtually any shape using simple measurements.

Square Footage Formulas

Different shapes require different formulas. For rectangles, multiply length times width. For circles, use the formula A = πr² (pi times radius squared). Triangles can be calculated with A = (base × height) / 2, or if you have all three sides, use Heron's formula: A = √[s(s-a)(s-b)(s-c)] where s is the semi-perimeter. Trapezoids use A = [(a + b) / 2] × h, where a and b are the parallel sides. L-shaped areas are calculated by subtracting the cutout rectangle from the main rectangle.

Common Area Calculations

• Rooms: A 12×15 bedroom is 180 square feet. Standard living rooms range from 200–400 square feet.
• Patios and Decks: A 10×10 patio is 100 square feet. A typical deck covers 200–400 square feet.
• Yards and Lawns: A quarter-acre lot is 10,890 square feet. A typical residential lot ranges from 5,000–10,000 square feet.
• Irregular Shapes: Divide irregular areas into rectangles, triangles, and circles, calculate each, and add them together.

Unit Conversions and Equivalents

Understanding unit conversions is key to applying these measurements across different contexts:

• 1 square yard = 9 square feet
• 1 square foot = 144 square inches
• 1 acre = 43,560 square feet = 4,840 square yards
• 1 square meter = 10.764 square feet
• 1 square kilometer = 247.1 acres

Tips for Accurate Measurements

• Measure twice, calculate once. Always double-check your measurements to avoid costly errors.
• Account for obstacles. When calculating room area, subtract closets and built-in features if not included.
• Add waste factor. For flooring, tile, and mulch, add 10–15% extra for cuts, breakage, and mistakes.
• Work in consistent units. Convert everything to the same unit before calculating to avoid mistakes.

When You Need Square Footage

Square footage calculations are essential for tile and flooring projects, determining how much paint you need, calculating landscaping material quantities, estimating installation costs, real estate valuations, and determining property taxes. Having an accurate calculation saves both time and money.