Security

Entropy Calculator

Estimate text entropy in bits using input length and a character-set model, entirely in your browser.

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Entropy estimate

Choose “Estimate entropy” to see the result here.

Processed locally in your browser. Inputs and results are not uploaded or saved by this page.

Estimated bits = code-point length × log2(character set size). Present ASCII classes contribute 26 lowercase, 26 uppercase, 10 digits, 32 punctuation and 1 space; other distinct observed code points add one each.
This character-set-model estimate assumes independent, uniformly chosen characters. It is not measured randomness, a cracking-time prediction or a security guarantee.

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What does this tool do?

Estimate text entropy in bits using input length and a character-set model, entirely in your browser. Inputs: Text or password. Outputs: Length, Character set size, Estimated entropy in bits.

How to use it

Enter the text or password to estimate. Choose “Estimate entropy”, then copy the result if needed. Clear removes text, secrets, file selection and results, and restores option defaults.