All tools

Password Entropy Estimator

Encode / Decode

Calculate a password's actual entropy in bits and estimated crack time

Paste a password and get its actual entropy in bits, computed as length times log2 of the character pool it draws from (lowercase, uppercase, digits, symbols, or other/Unicode), rather than the coarse 0-4 strength score the password generator tool shows during generation. That entropy figure then drives a strength label and estimated crack time across four scenarios, from a throttled online login form up to an offline GPU cracking cluster, so you can see roughly how much brute-force resistance a given password actually buys you. Because entropy alone overestimates resistance for guessable patterns, it also flags a few structural giveaways separately: repeated character runs, keyboard-adjacent sequential runs, passwords under 8 characters, and passwords using only one character class. It measures resistance to brute force over the theoretical character space, not real-world guessability against a breach database or dictionary of common passwords, so a password like "Password1!" can score reasonably here while still being one of the first guesses a real attacker tries. Everything runs in your browser; the password you type is never transmitted anywhere.

passwordentropysecuritystrengthcrack-time

How to use Password Entropy Estimator

  • 1.Type or paste a password to see its entropy in bits, computed from length and the character classes it actually uses.
  • 2.Check the estimated crack time across four attack scenarios, from a throttled login form to an offline GPU cracking cluster, to judge how much real protection the entropy figure buys.
  • 3.Read the warnings for structural giveaways like repeated or sequential characters that make a password easier to guess than its raw entropy suggests.

Frequently asked questions

How is this different from the strength meter on the password generator tool?
That meter is a coarse 0-4 score based on length brackets and which character types are present. This tool computes actual entropy in bits (length times log2 of the character pool) and translates it into crack-time estimates at several attack speeds.
Does this check my password against known breaches or common password lists?
No. It only measures brute-force resistance over the theoretical character space. A password can score well here while still being a well-known weak password in practice, which is why the pattern-based warnings (repeats, sequences, short length, single character class) are shown separately.
Is my password sent to a server?
No, the calculation runs entirely client-side in your browser and the password is never transmitted.
What does "average case" crack time mean?
It assumes an attacker finds the password after searching half of the total possible combinations on average, which is the standard convention used by most public entropy calculators, not a worst-case guarantee.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/password-entropy-estimator \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"password":"Tr0ub4dor&3xyzKL9!"}'

Get an API key from your dashboard · Full API docs →

Related tools

BcryptHash and verify bcrypt passwordsHashCSP Header BuilderBuild Content-Security-Policy headers with presets and validationNetworkhtpasswd GeneratorGenerate Apache .htpasswd entries with bcrypt, SHA-1, MD5, or plain password hashingHash