How Strong Is Your Password? Use Our Free Password Strength Checker

You probably know that "password123" is a bad password. But do you know whether your actual passwords are strong enough to survive a real attack? Most people cannot answer that question confidently — and neither strength meters on sign-up forms nor gut instinct are reliable guides. This article explains how password strength is genuinely measured and how to check any password in seconds.

What actually makes a password strong?

Password strength comes down to a single concept: entropy — the number of possible combinations an attacker would have to try to guess your password by brute force. Every bit of entropy doubles the number of guesses required.

Four factors drive entropy:

• Length: the single most powerful factor. Going from 12 to 16 characters is vastly more effective than adding a symbol to an 8-character password.
• Character variety: using uppercase letters, lowercase letters, numbers, and symbols expands the pool of possible characters at each position.
• Unpredictability: substitutions like "P@ssw0rd" are already in attacker dictionaries. Random sequences are far stronger than modified words.
• Uniqueness: a strong password that you reuse across sites is only as safe as the weakest site you used it on.

The seven criteria that matter

Criply's free password strength checker scores your password against seven specific criteria:

1. Length ≥ 8 characters — the minimum threshold for any meaningful resistance
2. Uppercase letters — adds a second character set (A–Z)
3. Lowercase letters — the baseline (a–z)
4. Numbers — adds digits 0–9
5. Special characters — symbols like !@#$%^&* further expand the character pool
6. Not a common password — checks against the most frequently attacked passwords
7. No repeated runs — flags patterns like "aaa" or "111" which dramatically reduce entropy

The resulting score maps to four strength levels — Weak, Fair, Strong, Very Strong — each with an estimated crack time ranging from "Instantly" to "Centuries."

Why common passwords are catastrophically bad

When attackers breach a site and obtain a hashed password database, they do not try every possible combination. They start with the most common passwords — there are published lists of billions of real passwords leaked in past breaches. "password", "123456", "qwerty", and "letmein" are tried in the first few seconds of any attack.

A 10-character common password like "sunshine99" offers almost no protection despite its length, because it matches patterns attackers try early. A random 10-character password with all character types, by contrast, would take years to crack.

The length vs. complexity trade-off

Many websites enforce complexity requirements (at least one uppercase, one number, one symbol) but allow short passwords. This is backwards. Here's why:

• An 8-character password with all character types has about 52 bits of entropy
• A 16-character password using only lowercase letters has about 75 bits
• A 16-character password using all character types has over 100 bits

At 100 bits of entropy, even a system trying a trillion passwords per second would take millions of years. At 52 bits, it takes hours to days with modern GPU clusters.

The practical conclusion: aim for 16+ characters. Use all character types for maximum entropy. Random generation is safer than patterns.

How to check and improve your password

1. Go to criply.co/security/password-strength-checker
2. Type or paste your password — it stays entirely in your browser, never transmitted anywhere
3. Review the strength score and the criteria checklist
4. If the password is weak, click Generate strong password to instantly create a 16-character cryptographically random password and copy it to your clipboard

For any password you want to keep using, the checklist tells you exactly what to improve: add length, add a character type, avoid the common-password list.

Frequently asked questions

Does typing my password into a checker make it less safe?
Only if the checker sends it to a server — which many do. Criply's checker runs entirely in your browser using JavaScript. Your password is never transmitted. You can verify this by turning off your internet connection and testing — it still works.

What is a realistic "time to crack" estimate?
The estimates assume a modern GPU cluster running billions of guesses per second. "Instantly" means crackable in under a second. "A few hours" means hours to days on dedicated hardware. "Years" means decades with current technology. "Centuries" means effectively uncrackable for any realistic attacker.

I have a strong password but it's the same everywhere — is that OK?
No. Password reuse is one of the most common causes of account takeovers. When a site is breached (and breaches happen constantly), your email and password combination gets tested against hundreds of other services automatically. Use a password manager to maintain a unique strong password for every site.

Related tools

• Password Strength Checker — Test any password instantly, free
• Password Generator — Generate cryptographically random strong passwords