Percentage Calculator 🔒 Your data never leaves your browser.
Three common percentage questions: X% of Y, X is what % of Y, and % change.
About this tool
A percentage calculator answers three closely related but different everyday questions: “what is X% of Y” (20% of 50 is 10), “X is what percent of Y” (10 is 20% of 50), and “what is the percentage change from X to Y” (going from 50 to 60 is a 20% increase, while going from 60 to 50 is about a 16.67% decrease). Mixing these up is one of the most common small math mistakes, so this tool keeps them as three separate, clearly labelled tabs — there's never any doubt about which question you're actually asking.
Percentages show up constantly: tips and sales tax, discounts and markups, exam grades, interest rates, and month-over-month or year-over-year comparisons in a spreadsheet. Pick the tab that matches your question, type in the two numbers, and the sentence-style result updates instantly as you type — entirely in your browser, with nothing sent to a server. Each tab remembers its own last inputs, so switching between them never loses what you typed.
Frequently asked questions
Why is "50 to 25" a -50% change, not a -100% change?
Percentage change is always measured relative to the STARTING value, not the ending value: (25 − 50) / 50 = -0.5 = -50%. A drop to zero would be -100% (since you'd lose the entire starting amount), but dropping only halfway to 25 is exactly a 50% loss of the original 50, hence -50%. This is a common point of confusion — always divide by the "from" number.