Find what percentage your exam marks are out of the total — e.g. 425 out of 500.
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.
Worked examples: 15% of 2400 = 0.15 × 2400 = 360. If a price rises from 2400 to 2760, the change is (2760 − 2400) ÷ 2400 × 100 = 15%. And 82 is (82 ÷ 100) × 100 = 82% of 100. A common mistake in the "% change" mode is dividing by the new value instead of the old one — the old value is always the base you're measuring the change against, regardless of whether it's bigger or smaller than the new one.
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.