Password Strength Checker
Check length and character variety without sending your password anywhere.
Check password strength safely
Your typed password stays in this tab and is never sent to analytics or a server.
Generated and checked locally in your browser with zero server transmission.
Understand Your Password Strength Estimate Safely
Many online password meters transmit what you type to a remote API or log keystrokes in third-party analytics scripts — turning a security check into a credential leak. The Pass Key's Password Strength Checker evaluates character length, pool diversity, and structural patterns 100% locally inside your browser tab so your typed string never leaves your device, meeting strict data-minimization standards under US CCPA/CPRA, Canadian PIPEDA, and European GDPR / UK GDPR.
If a password scores below Strong, replace it immediately using our Password Generator or Passphrase Generator. For deeper guidance, read our guide to checking password strength safely and how to create a strong password.
Password Score, Entropy & Attack Resistance Reference Table
A password's real-world security depends on whether it must resist online rate-limited login attempts or offline GPU hash cracking after a third-party database breach. Use the benchmark table below to interpret your strength score and entropy estimate:
| Strength Score | Estimated Entropy | Typical Example Pattern | Offline GPU Crack Time (100B/s) | Recommended Action |
|---|---|---|---|---|
| 0–39 / 100 (Weak) | < 45 bits | 8-char word or name + year (Summer2026) |
Instant – Minutes | Replace immediately |
| 40–69 / 100 (Moderate) | 45 – 65 bits | 10–11 mixed characters or 3 random words | Hours – Months | Upgrade to 16+ characters |
| 70–89 / 100 (Strong) | 66 – 95 bits | 14–15 random characters or 5-word passphrase | Thousands – Millions of years | Safe for standard unique logins |
| 90–100 / 100 (Very Strong) | 96 – 130+ bits | 18–24+ random characters across all 4 sets | > 1012 years (Uncrackable) | Ideal for email, banking & master vaults |
Password Entropy Calculator Formula & Multi-Hash GPU Crack Speeds (MD5 vs. SHA-256 vs. bcrypt vs. Argon2id)
Direct Answer: Cryptographic password entropy is calculated as H = L × log2(N), where L is character length and N is the character pool size (26 lowercase, 52 mixed-case, 62 alphanumeric, or 94 full printable ASCII). A password must have at least 75–100+ bits of entropy because you never know whether a website hashes passwords with a slow memory-hard function (Argon2id or bcrypt) or a fast legacy hash (MD5 or SHA-256).
| Password Type ( Entropy ) | Fast Hash: MD5 / NTLM (~180B/s) | Fast Hash: SHA-256 (~25B/s) | Slow KDF: bcrypt cost 12 (~120K/s) | Memory-Hard: Argon2id (~25K/s) |
|---|---|---|---|---|
| 8 chars alphanumeric (47.6 bits) | ~10 minutes | ~1.2 hours | ~29 years | ~138 years |
| 12 chars all 4 sets (78.6 bits) | ~83 million years | ~600 million years | ~1.2 × 1014 years | ~6.0 × 1014 years |
| 16 chars all 4 sets (104.9 bits) | ~6.8 × 1012 years | ~4.9 × 1013 years | > 1019 years | > 1020 years |
| 20 chars all 4 sets (131.1 bits) | > 1020 years | > 1021 years | > 1027 years | > 1028 years |
How Our Browser-Only Client-Side Strength & window.crypto.getRandomValues() Architecture Works
When you test a password in this tool or generate a replacement with our toolkit, every operation stays strictly inside your local browser sandbox:
- 100% Local JavaScript Evaluation: As you type into the password input field, an in-memory client-side function inspects character length, character-class breadth (lowercase, uppercase, digits, symbols), and repetitive or sequential weaknesses without ever making an HTTP request.
- Cryptographic Replacement Generation: When you switch to our generator tools to replace a weak credential, new secrets are created locally via
window.crypto.getRandomValues()using your operating system's hardware CSPRNG entropy pool. - How to Verify Zero Network Transmission Yourself: Open your browser's Developer Tools (
F12→ Network tab), type any test string into the checker, and click Clear. You will observe zero network requests (0 Fetch/XHR) and zero entries inlocalStorage,sessionStorage, or cookies.
Frequently asked questions
Is it safe to type my real password into an online strength checker?
Because The Pass Key evaluates length and character entropy strictly inside your local browser tab with zero network requests, nothing leaves your device. However, for maximum caution, you can also test a similar-pattern sample password.
How is password strength calculated by this tool?
The checker evaluates total character length, character-set diversity (lowercase, uppercase, digits, symbols), and common predictable patterns such as repeated characters or sequential runs.
Why does password length matter more than special symbols?
Each additional random character multiplies the total search space exponentially (by up to 94x per character), whereas adding a predictable symbol at the end of a short word is easily guessed by modern cracking rules.