Percentage Calculator

Percentages are one of those school-maths topics that keep coming back in everyday life: the discount in a shop window, the pay rise, comparing two offers, the tax. And every single time you juggle proportions and decimal points in your head, even though it always comes down to a handful of basic questions. The percentage calculator sorts exactly those questions into five clear modes and calculates the moment you have typed two values. No button, no waiting.

Mode one is the classic: X% of Y. What is 19% of 100? What does an 8% rise add to your gross pay? Enter the rate and the base value, and the calculator gives you the amount. Mode two flips it: share in percent. X is what percentage of Y? Perfect when you want to know what share an expense takes of your budget, or how much of a task is already done.

Mode three is the percentage change from an old value to a new one. Exactly what you need when the rent goes from 800 to 880 euros and you want to quantify the increase, or when you compare turnover across two years. The calculator shows a green up arrow or a red down arrow so the sign never flips the wrong way.

Mode four combines markup and discount. Add X% onto a base value or subtract it by simply putting a minus in front of the percentage. That gets you the final price after a 20% discount, or the gross amount after a percentage surcharge, in seconds. Mode five works out the percentage difference between two equal values when neither is the clear starting point.

Every mode shows you not just the result but the formula behind it. That is not decoration, it helps you follow the calculation and maybe do it yourself next time. And where maths hits a wall, like division by zero or a change measured from a starting value of exactly zero, the calculator tells you clearly why there is no meaningful answer instead of spitting out a cryptic error.

Enter numbers however you like: with a comma as is usual in Germany, or with a dot, with or without thousands separators. The calculator understands both and formats the result to match the language. One click copies the number to your clipboard, a tap on Escape resets everything. It all runs in the browser, no account, no data transfer, and works offline too.