Percentage Calculator

Percentage change measures movement from a starting value to a new one, so it depends on which came first. Percentage difference compares two values symmetrically against their average and gives the same answer whichever order you enter them.

Because each percentage applies to a different base. 100 rises to 150, then 50% of 150 is 75 — so you end up 25% below where you began. It is the single most common percentage mistake.

Margin is profit as a percentage of the selling price; markup is profit as a percentage of the cost. An item bought at 50 and sold at 100 has a 50% margin but a 100% markup — the same money, two very different numbers.

Divide by 1 plus the rate, do not subtract the percentage. For 20% tax, a total of 120 came from 100 (120 ÷ 1.2), not 96. The tax tab handles this both ways.

Yes, completely. There is no account to create, no trial that expires, no watermark on the output and no feature held back behind a paywall. The site is supported by unobtrusive advertising, not by charging you.

No. Percentage Calculator runs entirely inside your browser, so your input never leaves your device. You can confirm this by opening your browser's network tab — there is no upload request.

Yes. Because processing happens locally, there is no copy of your data on any server to leak, subpoena or lose. Nothing is logged and nothing is stored.

Yes. The interface is built mobile-first, with touch-friendly controls and layouts that adapt to small screens. Everything that works on a desktop works on a phone.

Once the page has loaded, yes. All processing is local, so you can carry on working if your connection drops.

Any current version of Chrome, Edge, Firefox, Safari or Opera, on desktop and mobile. If something behaves oddly, updating your browser resolves it in almost every case.

Yes. Whatever you produce here is yours — use it in client work, products, packaging or publications. There is no watermark, no licence to accept and no attribution required.

No. There is nothing to keep: your data is never transmitted, and it is cleared from memory as soon as you close or reload the page.