About this password strength checker
Estimate how strong a password is from its length and character variety, without ever sending it anywhere. Type or paste a password, and this tool detects which character types it uses — lowercase, uppercase, numbers, and symbols — estimates its entropy in bits from that character pool and length, and labels it Weak, Fair, Good, or Strong against common entropy thresholds. Use this workspace to prepare a result you can review before putting it to use. All processing takes place on your device, without an account or an upload of your inputs. Check the examples to understand the expected output, read the limitations for the supported scope, and reset the form when you want to start a separate task.
How it works
Entropy (bits) = length × log2(character pool size), where pool size adds 26 for lowercase, 26 for uppercase, 10 for digits, and 33 for symbols found in the password. Below 28 bits is Weak, below 36 is Fair, below 60 is Good, and 60 or above is Strong.
Try these examples
"abc"
Weak (≈14.1 bits)
"Tr0ub4dor&3"
Strong (≈72.3 bits)
Limitations & privacy
This is a length-and-variety heuristic, not a check against known breached-password lists or dictionary words — a long but common phrase can score well here while still being guessable. Up to 256 characters.
Inputs and results stay in this browser. Only tool identifiers are stored for your recently used tools. You can clear that history from the directory.
A few good questions
How is the result produced?
Entropy (bits) = length × log2(character pool size), where pool size adds 26 for lowercase, 26 for uppercase, 10 for digits, and 33 for symbols found in the password. Below 28 bits is Weak, below 36 is Fair, below 60 is Good, and 60 or above is Strong.
Are my inputs sent to a server?
No. Inputs and results are processed locally and are not uploaded or included in telemetry. Copying or downloading is your choice.
What are the limits of this tool?
This is a length-and-variety heuristic, not a check against known breached-password lists or dictionary words — a long but common phrase can score well here while still being guessable. Up to 256 characters.
Updated September 19, 2026