Percentage Calculator Online Free — 6 Calculation Modes
Calculate percentages instantly. 6 modes including change, add/subtract %, and find what % X is of Y.
🔒 Your file never leaves your browser. All calculations run locally.
How to Calculate Percentages Online
- 1
Choose a calculation mode
Select one of the 6 modes: find X% of Y, find what % X is of Y, percentage change, add/subtract %, or reverse percentage.
- 2
Enter values
Fill in the input fields. The result and formula update instantly.
- 3
Copy the result
Click the result to copy it to your clipboard.
Percentage problems are rarely hard — they are ambiguous. "What's 20% off 80?", "80 is 20% of what?", and "what percent of 80 is 20?" are three different calculations that sound nearly identical in English. That ambiguity is why this calculator offers distinct modes rather than one input box: pick the question you are actually asking, and the formula is applied correctly every time.
The everyday cases: discount math while shopping (price minus X%), tip calculation, VAT or sales tax in either direction (adding tax to a net price, or extracting the tax already inside a gross price), and grade or score conversion — 38 out of 45 as a percentage, without reaching for long division.
The one everyone gets wrong: percentage change. A rise from 50 to 75 is a 50% increase, but the fall from 75 back to 50 is only a 33% decrease — the reference value changes, so the percentages are not symmetric. This is also why a 50% loss needs a 100% gain to break even. The change mode uses the correct base automatically, which matters for anything from stock returns to year-over-year comparisons.
Percentage points vs. percent: when a rate moves from 10% to 12%, it rose two percentage points but twenty percent. Knowing which one a headline means is half of numeric literacy. For date-based proportions — how much of a year has elapsed — pair this with the age calculator, and for unit-based rates, the unit converter.