A percentage means “out of 100”. 20% means 20 out of every 100. Percentage Calculator uses two values to answer several different percentage questions at once.
Start with easy numbers
Set Value A to 20 and Value B to 100. Read these rows separately:
- 20% of 100:
20. This asks for a piece of 100. - 20 is what % of 100:
20%. This asks what share 20 is of 100. - Change from 20 to 100:
400%. This asks how much the value increased relative to where it started. It grew by 80, and 80 is four times the starting value 20.
The last answer is not 80% because the starting value matters. To find a decrease, swap the two values: a change from 100 down to 20 is -80%. This does not undo a 400% rise; each change uses a different starting value.
If you see an unusual result
Check which number you put in A and B, then read the whole label beside each output. Different rows answer different questions. With zero as the starting value, a percentage change cannot be calculated by dividing by zero; the tool shows a dash for that row. Do not treat a percentage without its starting value as enough information to make a decision.
Where your input goes
Processing runs in your browser. The tool does not upload your input to ilham.dev.
Related guide
For more background, read Calculators and Unit Conversion.
Questions you might have
- Why do a percentage rise and fall not cancel out?
- Because they are relative to different bases. A 50% rise followed by a 50% fall leaves you at 75% of where you started, not back at the beginning.