About CalcPercentages
A small, independent site that does one thing: percentage arithmetic, quickly, with the working shown, and without getting in your way.
What this site is
CalcPercentages is an independent project, not a company. It exists because most percentage calculators online bury a simple tool under pop-ups, forced sign-ups and three screens of scrolling before the input fields appear.
The design goal is that the calculator is usable within a second of the page loading, on a phone, on a slow connection. Everything else on the page — the explanations, the reference tables, the worked examples — sits below the tool, where it helps if you want it and stays out of the way if you do not.
The second goal is that the site should be worth reading, not only worth using. Anyone can put four input boxes on a page; the part that takes work is explaining why dividing a gross price by 1.2 is not the same as subtracting 20% from it, and why that distinction costs money on every invoice where it is got wrong.
What it deliberately does not do
- No account, no sign-up, no email address required for anything.
- No cookie banner beyond the consent message that advertising law requires in the EEA, the UK and Switzerland.
- No transmission of the numbers you type. There is no server that could receive them.
- No advertising inside or above the calculator itself. Ads sit below the tool, after the content.
- No interstitials, no newsletter overlay, no "read the rest" gate.
These are constraints rather than features, and some of them cost traffic or revenue. They are kept because a calculator you have to fight is not a calculator.
How it works
The site is a static, pre-rendered application. Every page is plain HTML delivered from a CDN, with the interactive calculator taking over once the JavaScript loads. There is no backend and no database.
Calculations happen entirely on your device. Nothing you type is sent anywhere, logged, or stored. The only thing kept between visits is your choice of decimal separator, held in your browser's local storage.
Accuracy
The formulas used are documented openly on the methodology page and repeated on each calculator, and the tool shows its working with your own numbers so you can check the result rather than trust it. If you find a result that looks wrong, please report it — see the contact page.
How the content is made
Pages are written by hand. Worked examples are calculated and checked against the tool they sit next to, and reference tables are recomputed rather than copied. Each page carries the date it was last reviewed.
How it is funded
The site is free and is funded by advertising placed below the calculator and outside the article text. There are no affiliate links, no sponsored content, and nothing on the site is written to sell a product. The reference tables and recommendations are not influenced by any commercial relationship, because there are none.
The privacy policy sets out what the advertising involves and how to opt out of personalised ads.
Related tools
The same approach is applied to a sibling calculator built by the same person: a matrix calculator at matrixcalc.net. It shares the design and the principle — the tool first, the explanation below it — but no data of any kind is shared between the two sites.
Last reviewed