What does this tool do?
Entropy Calculator measures the mathematical strength of a password in bits and shows the estimated time to crack it by brute force. It's built for users, sysadmins and developers who want to understand password security in concrete numbers rather than vague labels.
How to use it
- Choose the required options or length.
- Generate the secure result.
- Copy and store the result safely.
How entropy is calculated
The tool uses the formula: entropy = length × log₂(charset size). The charset size depends on whether your password contains lowercase (26), uppercase (26), digits (10), symbols (32) and other special characters (20). Longer, more varied passwords produce exponentially higher bit values; for example, a short digits-only PIN scores far lower than a long mix of letters, numbers and symbols.
Crack-time estimate
Results appear in four cards: bit entropy, charset size, strength level (from Very Weak to Very Strong) and estimated crack time. The time assumes 10 billion guesses per second, representing a modern GPU attack. As a rule of thumb, under 60 bits is weak, around 80 bits is reasonable, and 128 bits or more is considered very strong.
Frequently asked questions
Does high entropy always mean a secure password?
Not exactly. Entropy measures character variety and length, but it can't recognize dictionary words, keyboard sequences or common patterns like "P@ssw0rd"; those may be guessable despite a high bit score.
Why is the time based on 10 billion guesses per second?
That's a realistic assumption representing the offline brute-force speed of a powerful GPU. A faster rig could shorten the real time, so treat the estimate as an approximate upper bound.
Is my password sent anywhere?
No. The calculation runs entirely in your browser; the password you type is never transmitted to any server. A show/hide button lets you control its visibility while typing.
Is Password Entropy Calculator free?
Yes. Password Entropy Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Password Entropy Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.