Password Entropy
Calculate the entropy and estimated crack time of a password by character set and length
About this calculator
Calculate the entropy and strength of any password based on its length and character set. Entropy measures unpredictability in bits — more bits mean a harder password to crack by brute force.
How to use the Password Entropy tool
- Enter or paste your input into the field.
- Read the output — it updates instantly as you type.
- Adjust the options, if any, to fit your use case.
- Copy the page URL to share the exact result.
Common examples
- 8 lowercase = 37.6 bits (weak)
- 12 mixed-case + digits = 71.5 bits (strong)
- 16 all types = 105 bits (very strong)
- 4-digit PIN = 13.3 bits (very weak)
- 20 lowercase = 94.0 bits (strong)
Frequently asked questions
How does the Password Entropy tool work?
Enter or paste your input and the tool processes it directly in your browser, showing the result immediately. Nothing you type is uploaded to a server — the entire computation happens on your device.
When would I use the Password Entropy tool?
It is handy for development, debugging, design and administration tasks — whenever you need this transformation or check done quickly without installing anything or trusting a third-party service with your data.
How reliable are the results?
The tool implements the relevant standard or specification directly, so its output matches what compliant software produces. Edge cases such as empty or malformed input are reported clearly instead of failing silently.
Can I share a specific result with someone else?
Yes. Your input updates the URL, so copying the address bar and sharing the link reopens the tool in the same state for whoever clicks it.