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Min-Entropy Calculator
Estimate the min-entropy implied by a most-probable outcome, and see what that number does — and does not — tell you about an entropy source.
This tool runs entirely in your browser. Nothing you enter is sent to QRNG.io, iQrypto, an AI service or any third party.
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Used only to compare against the theoretical maximum bits per symbol.
How to read the result
Min-entropy answers a conservative question: if an attacker always guesses the single most likely outcome, how surprising is the source? A fair coin has p_max = 0.5 and therefore 1 bit of min-entropy per sample; a biased source with p_max = 0.25 yields 2 bits per sample. The further p_max is above 1/alphabet-size, the less min-entropy each sample carries.
The calculator does not model source physics, dependencies between samples, restart behavior, health tests or conditioning. A full SP 800-90B assessment uses dedicated estimators on large, carefully collected datasets — see the reading below and the local assessment kit for that workflow.
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Get a copy of your calculation and the interpretation notes as a downloadable report. The on-screen result above is free either way; the report file is generated in your browser — your numbers are never sent anywhere.
Primary sources
- NISTFinal2018-01SP 800-90B: Recommendation for the Entropy Sources Used for Random Bit Generation
NIST lists identified errata to be corrected in a future update/revision.