---
title: "Square Footage Calculator — Sq Ft, m², Yards, Acres & Cost"
description: "Free square footage calculator: add up multiple rooms, include a waste factor, and get the total in square feet, square metres, square yards and acres — plus material cost. See how floor area is measured by country."
url: "https://worldcalculators.org/calculators/square-footage/"
canonical: "https://worldcalculators.org/calculators/square-footage/"
---

# Square Footage Calculator

Free square footage calculator: add up multiple rooms, include a waste factor, and get the total in square feet, square metres, square yards and acres — plus material cost. See how floor area is measured by country.

## Quick answer

Square footage = length × width. Measure each room in the same unit, multiply length by width, and add the rooms together. For materials, multiply the total by (1 + waste %) — typically +10% — to know how much to buy.

## How to Measure Square Footage

For any rectangle, the area is simply length × width . The only rules are to measure both sides in the same unit and to be consistent: if you measure in feet, your answer is in square feet (ft²); if you measure in metres, it is in square metres (m²). To get the area of a whole home or project, measure each room as its own rectangle and add the results — that is exactly what the calculator above does when you add a new area.
For L-shaped or irregular spaces , draw a line that splits the footprint into two or more rectangles, measure each one, and enter them as separate areas. Round measurements up slightly rather than down, and remember that the figure you can buy is the measured area plus a waste allowance for cuts, breakages and pattern matching.

## Converting Between Square Feet, Metres & Yards

The same area can be written in several units. These are the exact conversion factors used by this calculator:

## How Floor Area Is Measured Around the World

The unit a home is advertised in — and even which space counts — changes from country to country:
Tip: always check whether a quoted area is net (usable internal space) or gross (including walls). France's loi Carrez and the international IPMS standards exist precisely to make that clear.

## Frequently Asked Questions

Square footage is length × width. Measure a rectangular room's length and width in the same unit (feet, metres, etc.), then multiply them. For a 12 ft × 10 ft room, the area is 120 square feet. To find the square footage of a whole house or project, calculate each rectangular area separately and add them together.
Break the space into simple rectangles. Draw a line to split the L-shape (or any irregular footprint) into two or more rectangles, measure each one, calculate length × width for each, and add the results. This calculator lets you add a separate area for each rectangle so the totals add up automatically.

## Sources & Methodology

Each area is calculated as length × width in the chosen unit and summed across all rooms. Totals are converted using exact factors (1 ft² = 0.09290304 m², 1 yd² = 0.83612736 m², 1 acre = 4046.8564224 m²). The waste factor multiplies the measured total by (1 + waste%), and material cost multiplies the waste-adjusted area by the price per unit area entered.
Standards and figures reviewed June 2026.

Source: https://worldcalculators.org/calculators/square-footage/
Markdown mirror of the HTML page. Prefer this URL for RAG; the interactive calculator still lives on the HTML page.