Square Footage Calculator

What is the Square Footage Calculator?

The Square Footage Calculator is a free, instant tool that turns the dimensions of a space into its floor area. It handles the four shapes that cover almost every real room — rectangles, squares, triangles, and circles — and lets you add room after room into one running total. That total is shown in both square feet and square metres at the same time, and an optional price per square foot turns it straight into a flooring, carpet, tile, or paint budget. It is built for homeowners, renters, and tradespeople who need a reliable area figure before they buy materials or request a quote.

How to measure a room

1. Choose the shape that matches the space, then pick whether you are measuring in feet, inches, metres, or centimetres.
2. Enter the dimensions the tool asks for. For a rectangle that is length and width; for a triangle it is the base and the height; for a circle it is the radius (half the diameter across the middle).
3. Press Add room to total. The room is added to the running total and listed below so you can remove it later.
4. Repeat for every section — an L-shaped living room is just two rectangles, and a bay window is a rectangle plus a small triangle.
5. Read the total square feet and square metres. Set a waste allowance to see the purchasing area, then add a price per square foot for material cost.

There is no Calculate button to wait on — the area of the current room updates as you type, so you can sanity-check a measurement before you commit it to the total and close the tab the moment you have your number.

The area formulas behind it

Each shape uses the standard geometry formula, with every input first converted to feet so the totals always line up:

• Rectangle: area = length × width
• Square: area = side × side
• Triangle: area = (base × height) ÷ 2
• Circle: area = π × radius²

To accumulate multiple rooms the tool simply adds each room's area together, because areas in the same unit are additive. For unit conversion it uses the exact relationships 1 ft = 12 in, 1 m = 3.280839895 ft, and 1 cm = 0.01 m, then reports the grand total in both square feet and square metres using 1 sq m = 10.763910417 sq ft. The purchase area is net square feet × (1 + waste percentage ÷ 100). Material cost is that purchasing area multiplied by the price per square foot.

Estimating material cost

The net area describes the space you measured. The waste allowance adds material for cuts, offcuts, or spare pieces without changing that net area. Choose a shortcut or enter a custom percentage from 0 to 100. The default is 0%, so no allowance is silently added. A 10% example is a planning assumption, not a guarantee: follow your supplier’s guidance for the product, pattern, and layout. Enter an optional price per square foot to price the area including waste. Package rounding, carpet roll layout, tax and labor are excluded; confirm the final order with your supplier.

Worked example

Say you are re-flooring an open-plan space made of a 15 ft × 12 ft living area and an adjoining 8 ft × 10 ft dining nook. Enter the first room (180 sq ft), add it, then the second (80 sq ft) for a total of 260 sq ft, which the tool also shows as about 24.15 sq m. At $3.50 per sq ft for laminate, the estimated material cost is $910; adding a 10% waste allowance you would buy closer to 286 sq ft, or about $1,001 of material. Swap in a circular rug area of 6 ft radius and the tool returns roughly 113 sq ft for that piece (π × 6²) without any extra math on your part.

Common use cases

• Buying the right amount of flooring, carpet, tile, vinyl, or laminate for a remodel.
• Estimating how much paint a room or wall needs before a trip to the store.
• Working out a property's livable square footage for a listing, lease, or rough valuation.
• Sizing rugs, turf, decking, patios, or a garden bed.
• Getting a quick material budget before asking a contractor for a formal quote.

Why use this one

Many square footage tools handle only a single rectangle or make you do the adding yourself. This one lets you combine multiple rooms of different shapes into one total, switch freely between feet, inches, metres, and centimetres, and read the result in both square feet and square metres at once. It is instant (areas update as you type, no reload) and private: every measurement is calculated in your browser, so nothing about your home is uploaded, stored, or shared. No account, no email, no app.

Frequently asked questions