Home › Tools › Home & Construction
Free Square Footage Calculator
Calculate area for rectangles, triangles, circles and trapezoids in several units.
What is the Square Footage Calculator?
Calculate area for rectangles, triangles, circles and trapezoids in several units.
It applies the matching area formula: length times width, half of base times height, pi times radius squared, or the average of two parallel sides times height. The area is multiplied by the number of shapes and shown in square feet, square metres, square yards and acres.
Home and building jobs are easier to price when you know how much material you really need. A quick estimate also helps you avoid buying too little or too much.
How to use the Square Footage Calculator
Using the square footage calculator takes a minute or two. Your entries are saved in this browser, so you can come back later and carry on.
Step 1
Enter the measurements of the area you are working on.
Step 2
Read the amount of material needed, including a waste allowance where relevant.
Step 3
Round up when you buy, and check the figures with your supplier.
Tips for better results
Split an irregular room into simple shapes, calculate each and add the results. Measure to the same unit throughout before comparing totals.
Add 5 to 10 percent for waste, cuts and mistakes.
Measure twice, order once, and check quantities with your supplier.
Privacy and where your data goes
Everything you type into the square footage calculator stays on your own device. Zapxa does not receive your numbers or documents. If you clear your browser data, your saved entries will be removed, so download a PDF of anything you want to keep.
Frequently asked questions
How do I measure an L-shaped room?
Split it into two rectangles, calculate each one, and add the results. Run the calculator once per rectangle, or set the number of identical shapes if the parts match.
For a circle, what do I enter?
Enter the diameter in the first field. The calculator halves it to get the radius and uses pi times radius squared.
Is the square footage calculator free?
Yes. It is free to use with no signup, no watermark and no usage limits.
Is my data private?
Yes. Your inputs are processed in your browser and saved only in its local storage. They are not uploaded to our servers.
Does it work on mobile?
Yes. Zapxa works on phones, tablets and desktops. Use the print button or download a PDF to keep a copy.
Related Home & Construction tools
- Concrete Calculator — Estimate cubic yards or cubic metres of concrete for a slab, plus bags and cost.
- Paint Calculator — Estimate gallons or litres of paint for a room's walls, ceiling and number of coats.
- Tile Calculator — Work out how many tiles and boxes you need for a floor or wall area.
- Flooring Calculator — Calculate how many boxes of flooring a room needs, with waste and cost.
- Roofing Calculator — Estimate roof area, roofing squares and shingle bundles from the house footprint and pitch.
- Gravel Calculator — Estimate cubic yards and tons of gravel for a given area and depth.