Password Strength Checker — How Strong Is Your Password?

A password strength checker measures how resistant your password is to cracking attempts. It analyzes length, character diversity, pattern detection, and entropy to estimate how long an attacker would need to guess it — from milliseconds to longer than the age of the universe.

What "Password Strength" Actually Means

Strength is not about having a capital letter and an exclamation point. It is about entropy — the mathematical measure of how many possible combinations an attacker must try to find your password through brute force.

The formula is straightforward: combinations = character_set_size ^ password_length. A password that uses only lowercase letters (26 characters) at 8 characters long has 26^8 = ~208 billion combinations. Switch to the full printable ASCII set (95 characters) and that same 8-character password jumps to 95^8 = ~6.6 quadrillion combinations.

But raw combinations only tell part of the story. Real attackers do not try every combination sequentially. They use dictionary attacks, pattern matching, and known breach data to shortcut the process. That is why "P@ssw0rd" — despite using uppercase, lowercase, digits, and symbols — is cracked instantly. It is in every attacker's dictionary.

How the Checker Scores Your Password

Open the Password Strength Checker and type any password. The tool evaluates:

• Length — the single most important factor. Every additional character multiplies the total combinations exponentially
• Character variety — using lowercase + uppercase + digits + symbols expands the character set from 26 to 95
• Pattern detection — keyboard walks (qwerty, 12345), repeated characters (aaa, 111), sequential patterns (abc, 789)
• Common password matching — checked against lists of the most commonly used and breached passwords
• Dictionary word detection — single dictionary words are trivially crackable regardless of length

Your password never leaves your browser. The entire analysis runs locally — no server requests, no data transmitted, no logs.

Real Crack Time Estimates

These estimates assume a single modern GPU cracking at ~10 billion hashes per second (bcrypt is dramatically slower, but many sites still use faster hashing):

Password	Type	Entropy (bits)	Estimated Crack Time
password	Dictionary word	~0 (in every list)	Instant
P@ssw0rd	Common substitution	~0 (in every list)	Instant — in top 100 most-used passwords
Summer2026!	Season + year + symbol	~28	Under 3 hours
tr0ub4dor&3	XKCD example (modified word)	~28	Under 3 hours
correct horse battery staple	4 random common words	~44	~550 years at 1,000 guesses/sec (online)
Gx7!mK2@pL9#	12-char random mixed	~79	~19 million years
j4H!x9Qm2@kL5nR7	16-char random mixed	~105	Longer than the age of the universe
diceware six word passphrase here ok	6 random diceware words	~77	~4 million years

Important caveat: these times assume truly random passwords. If your password follows any human-chosen pattern — a word with substitutions, a name plus a date, a keyboard pattern — attackers exploit those patterns with targeted dictionaries that crack orders of magnitude faster.

Privacy: Browser-Based vs Online Checkers

Not all password checkers are equal in how they handle your input:

Checker	Processing Location	Sends Password?	Privacy Rating
This tool	✓ Your browser (JavaScript)	✓ Never leaves your device	✓ Maximum privacy
Have I Been Pwned	✓ k-anonymity model	✓ Sends only first 5 chars of hash	✓ Excellent — widely trusted, audited
Bitwarden Strength Tester	✓ Your browser	✓ Never leaves your device	✓ Maximum privacy
NordPass Checker	~Server-side claimed local	~Unclear on implementation	~Moderate — trust the vendor
Kaspersky Password Checker	~Server-side processing	✗ Sends to Kaspersky servers	Limited — vendor receives your password
Random "check my password" sites	✗ Unknown	✗ Likely sent to server	✗ Avoid — no audit trail

A note on Have I Been Pwned: it is trustworthy. Troy Hunt's service uses k-anonymity — your browser hashes your password locally with SHA-1, sends only the first 5 characters of the hash to the API, and receives back all matching hash suffixes. Your full password hash never leaves your device. It is an elegant solution and is recommended by security researchers worldwide. The tradeoff: HIBP tells you if a password has appeared in a breach, while a strength checker tells you how resistant it is to brute-force cracking. They answer different questions.

Strength Checker Comparison

Feature	This Tool	Bitwarden	NordPass	HIBP Password	Kaspersky
Crack time estimate	✓ Yes	✓ Yes	✓ Yes	✗ No (breach check only)	✓ Yes
Breach database check	✗ No	✗ No	✓ Yes	✓ Yes — 900M+ passwords	✗ No
Entropy score shown	✓ Yes	✗ No (just meter)	✗ No	✗ No	✗ No
Pattern detection	✓ Common patterns	✓ zxcvbn library	~Basic	✗ N/A	~Basic
Runs locally in browser	✓ Yes	✓ Yes	~Claimed	✓ k-anonymity hash	✗ Server-side
Account required	✓ No	✓ No	✓ No	✓ No	✓ No
Ads	✓ None	✓ None	~Upsells NordPass	✓ None	~Upsells Kaspersky

What to Do After Checking

If your password scored poorly, here is the practical workflow:

1. Generate a new one — use the Password Generator to create a random 16+ character password or a 5-word passphrase
2. Store it properly — save it in a password manager (Bitwarden, 1Password, KeePassXC). Do not memorize 50 random passwords.
3. Enable 2FA — even a strong password can be phished. Two-factor authentication (TOTP app or hardware key) is your second layer.
4. Check for breaches — visit Have I Been Pwned to see if your email or old passwords have appeared in data breaches
5. Audit your other accounts — if you reused the weak password elsewhere, change it everywhere

Security Tools That Work Together

• Password Strength Checker — test any password's resistance to cracking
• Password Generator — create cryptographically random passwords and passphrases
• Hash Generator — generate SHA-256, MD5, and other hashes for verification
• Text Encryptor — encrypt sensitive text with AES-256 before sharing
• File Encryptor — encrypt files locally before uploading to cloud storage
• UUID Generator — generate unique identifiers for tokens and session IDs
• QR Code Generator — share Wi-Fi credentials securely via QR code
• Email Validator — verify email addresses when setting up new accounts