---
title: Password Strength Checker: Free Online Tool | Relic
description: Free password strength checker. Estimate how strong a password is, its entropy, and roughly how long it would take to crack, all in your browser. Nothing is sent anywhere.
canonical: https://relic.space/tools/password-strength-checker
source: https://relic.space/llms.txt
---
# Password Strength Checker

See how strong a password really is, its entropy in bits, and roughly how long it would take to crack. All in your browser, nothing transmitted.

Runs entirely in your browser. Nothing you type is uploaded.

...

Length

0

Character pool

0

Entropy

0 bits

Estimated time to crack (fast offline attack, \~100 billion guesses/sec)

Type a password above

At least 12 characters

Has lowercase (a to z)

Has uppercase (A to Z)

Has a number (0 to 9)

Has a symbol

No obvious patterns

Everything is computed on this page. Your password is never sent or stored anywhere.

## How the strength score works

There is no magic here, just math you can check. The tool looks at which character types you used (lowercase, uppercase, digits, symbols) to estimate the size of the pool an attacker would have to guess from, then computes **entropy** as `length * log2(pool)`. More length and more variety mean more bits, and each extra bit doubles the work. The crack-time estimate assumes a fast offline attack of about 100 billion guesses per second against a poorly protected hash, which is deliberately pessimistic. It runs entirely in your browser, so the password you type is never sent across the network.

## A strong password still needs a safe home

The catch with a genuinely strong password is that it is impossible to remember, so it ends up in a sticky note, a chat to yourself, or a plain text file. **Relic** is the end-to-end encrypted memory for everything you copy, masked by default and readable only by you, so the long random strings you generate stay both safe and one search away. Test a password here for free, then keep it somewhere only you can open.

## Frequently asked questions

How does this password strength checker work?+

It looks at which character types you used (lowercase, uppercase, digits, symbols) to estimate the pool an attacker would guess from, then computes entropy as length times log2(pool). It also runs pattern checks for common passwords, sequential runs, and repeated characters, and caps the score when it finds one so the rating stays honest.

What does entropy in bits actually mean?+

Entropy in bits measures how many guesses it takes to find your password: each extra bit doubles the work. So a 60-bit password is not slightly harder than a 50-bit one, it is roughly a thousand times harder. That is why the meter rewards length and variety, since both add bits.

How is the crack-time estimate calculated?+

It assumes a fast offline attack of about 100 billion guesses per second against a poorly protected hash, and that an attacker finds the password after guessing through half the keyspace on average. That is deliberately pessimistic, so a real attacker facing a properly hashed password would take much longer. Treat it as a worst-case guide, not a promise.

Why is my long password still rated weak?+

Raw entropy assumes the characters are random, but this tool also checks for real weaknesses. If it spots a common word like "password", a sequence like "1234", or the same character three or more times in a row, it caps the effective strength, because an attacker's dictionary and pattern rules crack those long before brute force does.

Is it safe to type my real password here?+

Yes. Everything is computed on this page in your browser, with no network request, so the password you type is never sent, logged, or stored anywhere. If you want a safe home for the strong passwords you settle on, Relic keeps everything you copy in an end-to-end encrypted vault that only you can open.

You just copied that. What if you never lost it?

**Relic** remembers everything you copy, forever, searchable on every device, and  end-to-end encrypted so only you can read it.

 250 MB free

[Download forWindows](https://relic.space/download/windows)[Download formacOS](https://relic.space/download/macos)[Download forLinux](https://relic.space/download/linux)[Download forAndroid](https://play.google.com/store/apps/details?id=relic.space.app&referrer=utm%5Fsource%3Drelic.space%26utm%5Fmedium%3Dwebsite%26utm%5Fcampaign%3Dcontent)[Download foriPhone](https://apps.apple.com/us/app/relic-clipboard-vault/id6800556025)

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