Square Footage Calculator

Calculate the area of a rectangle, circle, or triangle in sq ft and sq m.

Shape

Unit

Length (ft)

Width (ft)

Square Feet

300 ft²

Square Meters

27.8709 m²

Calculating square footage

Square footage is the standard measure of floor area in the US and Canada; the rest of the world uses square meters. One square foot equals approximately 0.0929 m², and one square meter equals about 10.764 ft². This tool handles three common shapes: rectangles (length × width), circles (π × r²), and triangles (½ × base × height). Enter your dimensions in feet or meters and both values are shown simultaneously. All calculations happen locally in your browser.

Related tools: Percentage Calculator · Aspect Ratio Calculator

Built and maintained by Meet Shah · Last updated 12 August 2026

What this tool is used for

Working out a room's area for flooring or paint.
Calculating a total across several rooms.
Converting between square feet and square metres while calculating.
Working out the area of a non-rectangular space.
Checking a quoted area against the dimensions.

Frequently Asked Questions

Which conversion factor is used?: The exact one. The international foot has been 0.3048 m by definition since the 1959 agreement, so a square foot is exactly 0.09290304 m² and a square metre is 10.76391… ft². Neither figure here is a rounded approximation.
How do I measure an L-shaped room?: Split it into rectangles, work each one out and add them. The same trick covers alcoves and bay windows — and subtract a rectangle for a chimney breast or a kitchen island. There is no single formula for an irregular floor plan.
Which triangle formula does it use?: Half the base times the perpendicular height — and "perpendicular" is the trap. The height must be measured at a right angle from the base to the apex, not along a sloping side. Using a slanted edge always overstates the area.
How much flooring should I actually buy?: Add a waste allowance on top of the measured area: roughly 5–10% for straight-laid planks, 15–20% for diagonal or herringbone patterns, and more in a room with many cuts. Materials are sold by the pack, so round up to whole packs.
Does square footage include the walls?: It depends who is asking. Gross internal area measures inside the external walls and includes internal partitions; carpet area counts only usable floor. A property listing and a flooring quote can differ by 10% or more on the same room.
How is a circular or curved area handled?: By splitting it into shapes you can measure — a rectangle plus a half-circle for a bay window, for instance. Approximating a curve with its bounding rectangle overestimates by roughly 21% for a full circle, which is a lot of unused flooring.