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Percentage Calculator

Free all-in-one percentage calculator. Work out what is X% of Y, what percent one number is of another, percentage increase or decrease, and add or subtract a percentage.

✓ Free ⚡ Instant 🔒 100% private
What is X% of Y?
What is % of ?
Enter both numbers to see the result.
X is what percent of Y?
is what % of ?
Enter both numbers to see the result.
Percentage increase / decrease
From to
Enter both numbers to see the change.
Add / subtract a percentage
± %
Enter both numbers to add or subtract.
X is P% of what?
is % of what?
Enter both numbers to find the whole.

🔒 All calculations run in your browser — nothing is uploaded.

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Free Percentage Calculator

This free online percentage calculator answers every common percentage question in one place — what is X% of Y, what percent one number is of another, the percentage increase or decrease between two values, how to add or subtract a percentage (handy for GST, tax and tips), and the reverse question “X is P% of what?”. It’s free, instant and private — every calculation runs in your browser and nothing is ever uploaded.

How to use the percentage calculator

  1. Pick the calculator that matches your question — each card is independent.
  2. Type your numbers into the blanks in the sentence.
  3. The result updates live as you type, or press Calculate.
  4. Leave a box blank and the result simply waits — no errors, no guessing.

How to calculate percentages (the formulas)

A percentage is just a fraction out of 100. The three formulas behind this tool are simple:

  • X% of Y = (X ÷ 100) × Y
  • X is what % of Y = (X ÷ Y) × 100
  • Percent change = ((new − old) ÷ old) × 100

Worked examples: 15% of 200 = (15 ÷ 100) × 200 = 30. To check the reverse, 30 is what percent of 200 = (30 ÷ 200) × 100 = 15%. For change, going from 200 to 250 = ((250 − 200) ÷ 200) × 100 = +25%. And to add a percentage, 200 + 18% = 200 + (18 ÷ 100 × 200) = 236.

Frequently asked questions

Is this percentage calculator free and private?
Yes. It’s completely free with no sign-up, and every calculation happens in your browser with JavaScript. Your numbers are never sent to a server.
How do I find what percent one number is of another?
Divide the part by the whole, then multiply by 100. For example, 30 out of 200 is (30 ÷ 200) × 100 = 15%. Use the “X is what percent of Y?” card to do it instantly.
How do I calculate a percentage increase or decrease?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 200 to 250 is ((250 − 200) ÷ 200) × 100 = +25%. A negative answer means a decrease.
How do I add GST, tax or a tip as a percentage?
Multiply the amount by the percentage and add it on. To add 18% GST to 200, calculate 18% of 200 = 36, then 200 + 36 = 236. The “Add / subtract a percentage” card shows both the plus and minus results at once.
What is the difference between percentage and percentage points?
A percentage point is the plain arithmetic gap between two percentages, while a percentage change is relative. If a rate rises from 10% to 15%, that is a 5 percentage point rise but a 50% increase, because 5 is half of the original 10.
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