Find what percentage one number is of another — the most basic percentage question.
This covers the three percentage calculations people search for most often, since "percentage calculator" actually means different things depending on what you're solving for. "X% of Y" answers a direct question like "what is 15% of 2400?" "% Change" answers "what's the percentage increase or decrease between two numbers?" (useful for comparing prices, scores, or any before/after figures). "X is what % of Y" answers "82 out of 100 is what percentage?" — the reverse of the first mode.
Percentage change is calculated as (new − old) ÷ old × 100, correctly showing a negative result for a decrease rather than just the absolute difference.
All calculations happen instantly in your browser as you type.
(New value − Old value) ÷ Old value × 100. A decrease correctly shows as a negative percentage, not just an absolute difference.
The first computes a value from a known percentage (15% of 2400 = 360). The second computes a percentage from two known values (82 out of 100 = 82%) — they’re inverse operations.
Yes, all three modes work with negative inputs where it makes mathematical sense, such as percentage change involving a negative starting value.