Password Strength Checker

How Password Strength Checker works

Estimate password entropy and offline crack time, with feedback on length and character pool. Everything happens inside this page: the tool reads your input, runs the calculation or conversion locally, and hands the result back to you. Nothing is transmitted, because there is no backend to transmit it to.

That design choice is deliberate. Most free tool sites upload your files to a server, process them there, and quietly keep a copy. Toolcin cannot do that — the site is a set of static files. If your connection dropped the moment the page finished loading, every tool would still work.

How the estimate is made

The checker measures the character pool your password draws from: 26 for lowercase, 26 for uppercase, 10 for digits and 33 for symbols, added together for whichever classes appear. Entropy is then length × log₂(pool).

That is an upper bound, not a measurement. “password123” has a large nominal pool and is cracked instantly, because it is a dictionary word plus a suffix — and no amount of pool arithmetic models that.

What the crack time assumes

The time shown assumes ten billion guesses per second against a fast offline hash. That is realistic for a stolen database of unsalted MD5 or SHA-1, and wildly pessimistic for a site that rate-limits logins to five attempts.

So the same password can be “instantly” in one context and “centuries” in another. The number describes the hash, not your account.

Why length wins

Each extra character multiplies the search space by the pool size. Adding a symbol to an eight-character password multiplies it by a factor of about 33 ÷ 62; adding a ninth character multiplies it by 62. Length is the lever that compounds.

What this tool deliberately does not do is check breach databases. That needs the password to be sent somewhere, which defeats the purpose of a local checker — use a service that hashes locally if you need that check.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions