Square Footage Calculator

To calculate square footage, multiply the length of a space by its width, making sure both measurements are in feet: square footage = length (ft) × width (ft). For example, a room measuring 12 feet by 10 feet is 12 × 10 = 120 square feet. If a room isn't a perfect rectangle, split it into smaller rectangular sections, calculate the area of each, and add them together for the total.

A 12x12 room is 144 square feet, calculated as 12 feet × 12 feet = 144 sq ft. This is one of the most common room sizes for bedrooms, and it's a useful benchmark for estimating flooring, paint, or carpet costs since many suppliers price per square foot.

Calculate the square footage of each room individually by multiplying its length by its width, then add all the individual areas together to get the total square footage. This calculator handles that automatically — enter each room's dimensions as a separate row, and it sums every room's area into a running total, which is exactly how contractors estimate flooring and paint for an entire house or renovation project.

You should buy more flooring than your exact measured square footage to account for cuts, mistakes, and pattern matching — this extra amount is called a waste factor, typically 10% for simple rectangular rooms and up to 15-20% for rooms with diagonal cuts, angles, or patterned materials like tile and hardwood. For example, 270 square feet with a 10% waste factor means you should purchase 270 × 1.10 = 297 square feet of material.

One gallon of paint typically covers about 350 square feet of wall surface for a single coat, so divide your total wall area by 350 to estimate gallons needed. Wall area is calculated as the perimeter of the room (2 × (length + width)) multiplied by the ceiling height. Most professionals recommend two coats for even coverage and true color, which roughly doubles the paint you'll need.

To convert square feet to square meters, multiply by 0.092903 (1 sq ft ≈ 0.0929 sq m). To convert square feet to square yards, divide by 9 (1 sq yd = 9 sq ft), since a square yard measures 3 feet by 3 feet. This calculator includes a feet/meters toggle so you can enter room dimensions directly in whichever unit you prefer without doing the conversion by hand.