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Open toolPercentage Calculator
Calculate a percentage of a value, a ratio percentage or signed percentage change.
Maximum 200,000 characters. Input is not stored.
Ready. Use Ctrl/⌘ + Enter to run.
Completed and failed run counts are stored only on this device.
How to use this tool
For percent-of, enter a value and percentage. For what-percent, enter a part and total. For percent-change, enter the initial and final values.
Supported input and limits
Finite JavaScript numbers only. Ratio total and change initial value cannot be zero. Negative initial values use absolute(initial) as the change denominator. Decimal rounding applies.
Frequently asked questions
Why is an increase from -100 to -50 +50%?
Change is (final − initial) / absolute(initial) × 100, so the sign reflects numerical increase or decrease.
Is my input uploaded?
No. Processing happens in a disposable worker on your device. Only local success/failure counts are saved; input is never stored.
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