Category 9 — Cryptography / Security

Password Strength Meter

Real-time entropy analysis, crack-time estimation, and improvement suggestions.

0 bits

How to use this tool

  1. Type or paste a password into the Type a password… field — the analysis updates on every keystroke.
  2. Read the entropy total in bits and the color-coded strength label next to the meter.
  3. Check estimated crack times under the three scenarios: Online attack (1k/s), Offline fast hash (10B/s), and Offline slow hash (10k/s).
  4. Open the Score Breakdown panel to see how length, character classes, and sequence/repeat penalties add up.
  5. Follow the Suggestions list to raise a weak score, and use Show/Hide to reveal the field.

Why this tool is helpful

Audit passwords before reuse

Get an instant entropy and crack-time read on an existing or candidate password instead of relying on "looks strong enough".

Estimate real-world attack cost

See the gap between a slow online guess, a fast GPU hash, and a slow KDF — the same password can crack in seconds or centuries depending on the scenario.

Follow length-over-complexity guidance

NIST now favors long passphrases over forced character classes. Watch how added length raises entropy far faster than a single symbol.

Spot weak patterns

Sequence and repeat penalties plus a top-100 common-password check surface 123456, password, and keyboard walks that pure length misses.

Explain security decisions to others

Show teammates or clients the concrete bit count and crack time behind a password-policy decision.

Stay private

Analysis runs entirely in your browser. Passwords are never uploaded, logged, or sent anywhere.

FAQ

What does the meter actually measure?

It estimates a password's entropy in bits — the logarithm of the number of possible guesses — then converts that into a crack-time estimate for three attack speeds.

How is entropy calculated?

The tool counts the character pool you use (26 lowercase, 26 uppercase, 10 digits, 33 symbols), multiplies length by log2(pool), then subtracts penalties for sequential runs like abc or 123 and for repeated characters.

What do the three crack-time scenarios mean?

Online attack (1k/s) models guessing against a live login form. Offline fast hash (10B/s) models a GPU cracking a fast hash like MD5. Offline slow hash (10k/s) models a slow KDF like bcrypt or Argon2. Each divides 2^bits by its guesses-per-second rate.

Why does a long password still score low?

If it's built from sequences (123456), repeated characters, or appears in the top-100 common list, the sequence/repeat penalty and the common-password flag reduce its effective entropy.

What's a good score to aim for?

The meter labels Good at roughly 36 bits and Strong/Very Strong above 50/70 bits. Aim for 50+ bits with a long, unique passphrase or a password manager.

Is this a guarantee that my password is safe?

No. It's a heuristic estimate based on character classes and common patterns — it can't know if the password is reused, leaked, or targeted. Use it as guidance, not proof.

Does my password leave my browser?

Never. All analysis runs locally in JavaScript, and the password is never transmitted to or stored on any server.