Square Footage Calculator

The basic square-footage formula

For a rectangle, multiply length by width. A room that measures 12 feet by 15 feet contains 180 square feet. This calculator lets you add several rectangular sections, making it useful for connected rooms, walls, patios, flooring zones, or an L-shaped space divided into smaller rectangles.

Measuring irregular spaces

Break an irregular outline into rectangles that do not overlap, calculate each section, and add them. For triangular sections, use one-half times base times height and enter the equivalent area separately in your planning notes. Measure in consistent units; this version expects feet and allows decimal values such as 10.5 feet.

Why add a waste allowance?

Flooring, tile, lumber, wallpaper, and other materials rarely fit with zero waste. Cuts, defects, pattern matching, and future repairs require extra material. Ten percent is a common planning value for straightforward layouts, but intricate patterns or diagonal installation may need more. Follow the product or installer's recommendation.

Cost estimate example

Two areas measuring 180 and 120 square feet total 300 square feet. Adding 10% waste produces 330 square feet to purchase. At $3.25 per square foot, the estimated material cost is $1,072.50 before tax, delivery, labor, underlayment, or other supplies.

Important limitations

This is an estimating tool, not a construction plan. Verify measurements at the site and consult the product coverage information. Pack sizes may require rounding up to complete boxes or bundles.