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.
🔒 All calculations run in your browser — nothing is uploaded.
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
- Pick the calculator that matches your question — each card is independent.
- Type your numbers into the blanks in the sentence.
- The result updates live as you type, or press Calculate.
- 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.