Percentage Calculator
Work out percentages, increases and decreases instantly.
Percentages come up constantly: tips, discounts, grades, taxes, raises, and price changes. This free percentage calculator answers the three questions people ask most. What is X percent of Y? What percent is X of Y? And how much did something change in percent? Type two numbers and get the answer instantly, with the steps shown so you can check the math. It runs entirely in your browser, with no account and no signup.
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About Percentage Calculator
Percentages are everywhere and quietly easy to get wrong. Is it X percent of Y, X as a percentage of Y, or the percentage change from X to Y? Mixing up those three is behind most everyday percent mistakes, the tip that overshoots, the “50% off, then 50% back on” confusion, the raise that looks bigger than it is. This tool keeps the three modes separate and clearly labeled: pick the question you're actually asking, enter the two numbers, and get an instant answer that updates as you type.
The mode that trips people most is percentage change, because the denominator is always the starting value. Going from 80 to 100 is a 25% increase; coming back from 100 to 80 is a 20% decrease, the same $20 move, different percentages, because the base changed. That asymmetry is why “down 50%, up 50%” doesn't return you to where you started (it leaves you 25% short). Once you see the base rule, percent-change headlines get much easier to read critically.
Small habit worth building: reverse-check any percentage that matters. If the tool says 18% of a $64 bill is $11.52, confirm that $11.52 is indeed 18% of $64 by running it backward in the second mode. Two seconds of verification catches the typos that turn a good tip into an awkward one.
How to use Percentage Calculator
- Pick the calculation you need.
- Enter the two numbers.
- Read the answer and the steps shown.
- Change the numbers to try another calculation.
Why use this tool?
- Three percentage modes in one tool
- Instant answers as you type
- Free with no signup
Tips for best results
- Pick the mode before typing numbers, most percent mistakes come from answering the wrong question, not bad arithmetic.
- For percent change, the denominator is always the original value; a 50% drop then a 50% rise leaves you 25% below the start.
- Reverse-check important results: compute the percent forward, then verify it backward in “X as % of Y” mode.
- When estimating tips mentally, compute 10% (move the decimal) and scale: 20% is double, 15% is 10% plus half again.
- Round only at the end, rounding mid-calculation on chained percentages compounds the error.