Password Strength Checker
Test password strength in real time. See crack-time estimates, character requirements, and tips to create stronger passwords.
Our free Password Strength Checker evaluates any password in real time and tells you how strong it is, which character requirements it meets, and approximately how long it would take an attacker to crack it… Paste or type your input above; results update immediately. The tool runs in your browser and we don't store your data.
About This Calculator
Our free Password Strength Checker evaluates any password in real time and tells you how strong it is, which character requirements it meets, and approximately how long it would take an attacker to crack it using brute-force methods. Use it when creating new passwords for email, banking, social media, or work accounts to make sure they are resistant to common attacks. The tool checks for length, uppercase and lowercase letters, numbers, and special characters, then calculates entropy and estimated crack time. Everything runs locally in your browser — your password is never transmitted over the network or stored anywhere.
How It Works
As you type, the checker analyzes your password against several criteria: minimum length (12+ characters recommended), character diversity (uppercase, lowercase, digits, special characters), and overall entropy (a measure of unpredictability). Entropy is calculated as log2(character_set_size ^ password_length). The estimated crack time assumes an attacker performing 10 billion guesses per second (a realistic speed for a GPU-based attack). A password with 60+ bits of entropy is considered strong; 80+ bits is very strong. The strength meter, color-coded feedback, and crack-time estimate update instantly as you modify the password.
How to Use
- Enter your values in the calculator fields above
- Click the calculate button or let the calculator auto-update
- Review your results instantly
- Adjust values as needed to see different scenarios
Frequently Asked Questions
What makes a strong password?
Length is the most important factor — aim for at least 12 characters, ideally 16+. Include a mix of uppercase letters, lowercase letters, numbers, and special characters (!@#$%^&*). Avoid dictionary words, names, dates, keyboard patterns (qwerty, 12345), and anything related to your personal information. A passphrase like "correct-horse-battery-staple" is both strong and memorable.
How is the estimated crack time calculated?
The tool estimates the character set size (26 for lowercase only, 52 for mixed case, 62 with digits, 95 with special characters) and raises it to the power of the password length to get the total number of possible combinations. It then divides by 10 billion (guesses per second for a modern GPU rig) to estimate the time to brute-force the password. Real-world attacks may also use dictionaries and patterns, which can be faster — so the estimate is an upper bound.
Is my password sent to any server?
No. All analysis happens locally in your browser using JavaScript. Your password never leaves your device — it is not transmitted, logged, or stored. This is the safest way to check password strength online.
Should I use a password manager instead of memorizing passwords?
Yes. A password manager generates and stores unique, strong passwords for every account, so you only need to memorize one master password. This eliminates password reuse, which is the number-one cause of account breaches. Popular options include Bitwarden, 1Password, and KeePass.
What is two-factor authentication and should I use it?
Two-factor authentication (2FA) adds a second layer of security beyond your password — usually a code from an app (Google Authenticator, Authy) or a hardware key (YubiKey). Even if your password is compromised, an attacker cannot log in without the second factor. Enable 2FA on every account that supports it, especially email, banking, and social media.
How often should I change my passwords?
Current security guidance (NIST SP 800-63B) says you should change passwords only when there is evidence of a breach — not on a fixed schedule. Frequent forced changes lead to weaker passwords (people just increment a number). Instead, use a long, unique password for each account and enable 2FA.
Why Use Our Free Password Strength Checker Online?
Our Password Strength Checker runs in the browser so you can format, convert, or generate without sending data to our servers. No account needed—paste or type, get your result. We offer more dev tools (JSON, Base64, JWT, UUID, timestamps, and more) in the list below.