About SqFt Math
By Rohit GaurLast updated October 1, 2026Report a mistake
SqFt Math is a free square footage calculator. It measures rooms, adds them up, takes off what is not floor, and shows the answer in the units the person on the other end of the conversation uses.
Why it exists
Most area calculators are a box, a button and an answer. That is fine until the answer matters — when you are ordering flooring, checking a quote, or deciding whether a flat is as big as the listing says. Then you want to see the working, and you want to know where the numbers came from.
So this one shows its working. Every room prints its own arithmetic, every drawing is to scale, and the methodology page lists every formula and conversion constant with its source. Nothing is a rounded approximation of something that has an exact value.
Who builds it
It is built and maintained by Rohit Gaur. Pages are drafted with an AI assistant and held to the checks below before they go live. Questions, corrections and bug reports all go to the same address: contact@sqftmath.com.
How it is kept honest
- Every formula has fixed test cases and property tests that run against thousands of random inputs on every change.
- The drawings are tested against the maths: the outline on screen must enclose exactly the area the calculator reports, or the build fails.
- Every page is checked for accessibility problems automatically, and the whole site is checked for unfinished content — filler copy, missing images, broken links — before it can ship.
- Corrections are dated on the changelog.
What it does not do
It calculates floor area for practical work: materials, quotes and sanity checks. The whole-house calculator applies the rules of ANSI Z765 — as Fannie Mae’s Selling Guide and the Appraisal Institute restate them — to the measurements you give it: what counts as finished area, what never does, and above and below grade kept apart. It cannot take those measurements for you, so its figure is only as good as the tape behind it.
It keeps nothing you type on a server: the arithmetic runs in your browser. The one thing typed that leaves it is an address searched for on the acreage map, which goes to Esri to find the place. The rules and where each one was read are on the methodology page, and what is kept where is in the privacy policy.