Free square footage calculator. Find the area of a rectangle, circle, or triangle in square feet or square meters, with multiple rooms and a waste percentage.
A square footage calculator finds the area of a space from its dimensions: length times width for a rectangle, pi times radius squared for a circle, and half of base times height for a triangle. It then converts that area between square feet and square meters and can add a waste percentage for materials like flooring or paint.
132 sq ft
Total with waste (sq ft)
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Square Footage Calculator
Almost any room or space can be broken down into a handful of basic geometric shapes: rectangles for most rooms and walls, circles for round tables, patios, or pools, and triangles for gable ends, sloped ceilings, or oddly-angled corners. Once you know which shape (or combination of shapes) matches your space, calculating the area is a matter of plugging measurements into the right formula.
A rectangle's area is length times width. A circle's area is Ļ (pi, approximately 3.14159) times the radius squared. A triangle's area is half the base times the height. This calculator handles all three, so you don't need to remember or manually apply the formulas.
Feet vs. Meters
Square footage and square meters measure the same thing ā area ā just in different unit systems. The US commonly uses square feet for real estate, flooring, and construction, while most other countries use square meters. One square meter equals about 10.7639 square feet, so a 100 sq m apartment is roughly 1,076 sq ft.
This calculator lets you enter your measurements in either feet or meters and shows the resulting area in both units simultaneously, which is useful when comparing a US-listed floor plan to a metric one, or when buying materials priced per square meter for a US-measured room.
Waste Percentage
Ordering exactly enough tile, flooring, or paint to match your calculated square footage almost always leaves you short. Cutting tiles or planks to fit around doorways, closets, and irregular edges wastes material, and having zero buffer means a delayed project if you run out mid-installation and the retailer is out of your exact batch or dye lot.
A 10% waste allowance covers most straightforward rectangular rooms. Complex layouts, diagonal tile patterns, or rooms with many corners and cutouts often need 15-20% extra. This calculator applies your chosen waste percentage on top of the raw area to show the total amount to actually purchase.
Limitations
This calculator computes flat, two-dimensional area for three basic shapes. It doesn't handle compound or irregular rooms directly ā for an L-shaped room, calculate each rectangular section separately and add the totals. It also doesn't account for vertical surfaces like walls or ceilings, which need their own height-based calculation, or material-specific factors like tile sizing and grout lines.
For material quantities based on an area you've already calculated here, see our tile calculator or paint calculator for the next step.
Practical Use Cases
Buying flooring or carpet
Finding the exact area to order the right amount of material, with a waste allowance included.
Comparing real estate listings
Converting between square feet and square meters when comparing properties listed in different unit systems.
Planning a room layout
Checking whether furniture or a rug of a given size will fit comfortably in a room's total area.
Estimating a renovation quote
Getting a rough area figure before requesting quotes from contractors who price by square footage.
Calculating patio or deck size
Finding the area of an outdoor rectangular, circular, or triangular space for materials or permits.
For a rectangular room, multiply length by width, both measured in feet. A 12 ft by 10 ft room is 12 Ć 10 = 120 square feet. For irregular rooms, split the space into rectangles, triangles, or other simple shapes, calculate each area separately, and add them together.
Divide the square footage by 10.7639 (since 1 square meter equals about 10.7639 square feet). A 120 sq ft room converts to about 11.15 sq m. This calculator does the conversion automatically alongside the area calculation.
A common rule of thumb is 10% extra for straightforward rectangular rooms, and 15-20% for rooms with lots of cuts, angles, or a diagonal installation pattern (common for tile and flooring). Always check the specific material manufacturer's recommendation, since cut waste varies by product.
Use the formula Ļ Ć radiusĀ². Measure the radius (distance from the center to the edge, or half the diameter) and this calculator squares it and multiplies by Ļ (approximately 3.14159) to get the area.
This calculator's room count field multiplies a single room's area by however many identical rooms you enter, useful when several rooms share the same dimensions (like matching bedrooms). For rooms of different sizes, calculate each one separately and add the totals.