Percentage Calculator
The three percentage questions people actually ask, answered instantly: what percent, what amount, or what changed.
Last updated: August 5, 2026
Three questions, three formulas
Almost every percentage question in daily life is one of these three, and each has a tiny formula worth knowing:
- What percent of Y is X? — divide X by Y, multiply by 100. Useful for "what grade is this?", "what share of the budget is rent?", "how much of the month is left?"
- What is X% of Y? — multiply Y by X, divide by 100. The classic "18% of $75" question, handy for tips, discounts and taxes.
- Percent change from X to Y? — (Y − X) ÷ X × 100. Used for price rises, weight loss, population growth, salary bumps.
Each mode changes the labels of the two fields and the result automatically, so you never have to translate your question into a format the tool expects.
The formulas
Worked examples
30 out of 120 → 25% (the share of 120 that 30 represents).
18% of 75 → 13.5 (a tip on a $75 bill).
From 50 to 60 → +20% (a salary rise from $50,000 to $60,000).
Beware the last one going in reverse: falling from 60 back to 50 is −16.7%, not −20%. Percentage changes are measured against the starting value, and percentages going down are always measured from a larger base.
Related calculators
The questions people usually ask right after this one.
| Tip Calculator | Split a bill and figure the tip, per person, without the maths. |
|---|---|
| Discount Calculator | See the sale price after a percent off, and exactly how much you save. |
| Sales Tax Calculator | Add tax to a price or pull the tax out of a total you have already paid. |
| Age Calculator | Work out an exact age in years, months and days from any birth date. |
Frequently asked questions
What does 50% of 100 equal?
50. In general, X% of Y equals Y% of X, which is a handy mental shortcut: 8% of 25 is the same as 25% of 8, i.e. 2.
How do I find the original price after a discount?
If the final price is F after a D% discount, the original was F ÷ (1 − D ÷ 100). For example $80 after 20% off means the original was $100. Our Discount calculator does this for you.
Why is a 50% drop followed by a 50% rise not back to the start?
Because each change is measured from where you are. 100 drops 50% to 50, then rises 50% of 50, to 75. Percentages are relative; that is why they trip people up in bargains and markets alike.