Percentage Calculator
About the Percentage Calculator
Answer the three questions people search for most: what is X% of Y, X is what percent of Y, and the percentage change from one number to another. Switch modes and read the result instantly. Everything is computed locally in your browser — no sign-up, no data sent anywhere.
This tool works in your browser: the files and text you use are processed on your device and are not uploaded.
How to use it
- Pick a mode: “X% of Y”, “X is what % of Y”, or “% change”.
- Enter the two numbers.
- Read the answer below — it updates as you type.
Frequently asked questions
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100: (part ÷ whole) × 100. For example, 30 out of 200 is (30 ÷ 200) × 100 = 15%.
How is percentage change calculated?
Percentage change = ((new − old) ÷ old) × 100. Going from 100 to 150 is a +50% change; from 100 to 50 is −50%. A positive result is an increase, a negative one a decrease.
What is the difference between percentage change and percentage points?
A change from 10% to 15% is a 5 percentage-point rise, but a 50% relative increase. Percentage points compare the values directly; percentage change compares them proportionally.
How do I find the original number before a percentage was added?
Divide by (1 + rate). If a price is 117 after 17% tax, the original is 117 ÷ 1.17 = 100. The GST/VAT tool does this automatically in “remove tax” mode.