Password Strength Checker
Check a password's strength based on its length and character variety.
Inputs
Saved Scenarios
— select 2+ to compare| Metric | |
|---|---|
Strength Score
0
Rating
Empty
Spark says
Formula
- Classes
- — Count of character types used: lowercase, uppercase, digits, symbols
What is the Password Strength Checker?
This is a composition-based heuristic — it rewards both length and character variety (lowercase, uppercase, digits, symbols), which are the two factors most guidance agrees matter most for resisting guessing attacks. For a bits-of-entropy calculation instead, see the Password Entropy Calculator.
How to use it
- 1 Type a password to see its strength score and rating.
Worked examples
Limitations
- •This runs entirely in your browser and is never sent anywhere — but it's still a heuristic score, not a guarantee: a long password made of a common phrase can score well here while still being easy to guess for an attacker with a dictionary of common phrases.
Frequently asked questions
Is my password sent to a server when I use this?
No — this calculator computes entirely client-side in your browser; the password never leaves your device or gets transmitted anywhere.
How is this different from the Password Entropy Calculator?
Entropy measures theoretical randomness in bits, useful for comparing generated passwords. This strength check is a simpler, composition-based heuristic closer to what many signup forms show you.