Square Footage Calculator
Find the area of a room or space in square feet and square metres, plus flooring cost.
Results update as you type.
About this calculator
A square footage calculator measures the floor area of a room or space so you can buy the right amount of flooring, carpet, paint, turf or tile. For a plain rectangle the area is simply length × width; an L-shaped room is split into two rectangles whose areas are added; a circular space uses π × radius² (the radius is half the diameter). The result is given in both square feet and square metres (1 sq ft = 0.092903 sq m), and an optional price per square foot estimates the material cost.
Worked example: a 12 × 10 ft room is 120 sq ft, or 120 × 0.092903 ≈ 11.15 sq m. Add an L-shaped alcove of 6 × 4 ft (24 sq ft) and the total becomes 144 sq ft. At $3 per square foot the flooring estimate is 144 × 3 = $432 before waste.
Always add a waste allowance when ordering — 5–10% for straight rooms, more for diagonal or patterned layouts. It is used for flooring, carpet, tiling, painting, landscaping and any job priced by area.
Frequently asked questions
How do I measure the square footage of an L-shaped room?
Split the room into two rectangles, work out length × width for each, then add them. This calculator does that when you pick the L-shape option and enter the second rectangle under advanced options.
How many square feet are in a square metre?
One square metre is about 10.764 square feet, and one square foot is 0.092903 square metres. The calculator shows both units so you can order flooring sold either way.
Should I add extra for waste?
Yes. Add roughly 5% for a simple rectangular room and 10–15% for diagonal, herringbone or heavily patterned layouts, plus a little more for a room with many cut-outs.
How do I measure a room for square footage?
Measure the length and the width at the longest points with a tape or laser measure, in the same unit, and multiply. For a room that is not a simple rectangle, break it into rectangles, measure each, and add — which is exactly what the L-shape option does.
How do I find the area of a round or circular space?
Pick the circle option and enter the diameter (the full width across). The calculator uses π × (diameter ÷ 2)² — so a 10 ft circle is 3.14159 × 5² ≈ 78.5 sq ft.
How much flooring should I buy for the square footage?
Buy your measured area plus a waste margin — about 5% for a straight rectangular layout, 10% for most rooms, and 15% or more for diagonal, herringbone or heavily patterned installs. Enter a price per square foot to see the material cost for the base area, then add the waste when you order.
API — use this calculator from code
Call this calculator as a free JSON endpoint — no key required. Send the field values below as query parameters or JSON. Read the full API docs →
Endpoint
GET https://calculator.free/api/v1/square-footage/curl
curl "https://calculator.free/api/v1/square-footage/?shape=rectangle&length=12&width=10"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/square-footage/?" + new URLSearchParams({
"shape": "rectangle",
"length": "12",
"width": "10"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.