Percentage, change and discount calculator
Enter any two values in a row and the answer updates as you type. Each result shows the exact formula used, including how zero and negative values are handled.
Free to useRuns in your browser — files are not uploadedInstant results · computed in your browser
How to use it
- Pick the calculation that matches your question.
- Fill in the two known values.
- Read the result and the formula line; copy the numbers you need.
Limits & formats
Plain arithmetic only — no rounding beyond 10 significant digits. A zero denominator shows an explicit error instead of a wrong answer. Percentage change uses the first value as the base.
Privacy
Everything is computed locally in this browser tab; nothing is sent or stored.
Related tools
More tools are on the way.
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