How to Check If Your Password Is Strong Enough (and Fix It)
A weak password is an open invitation to hackers. But how do you know if your password is truly secure? Toolzo’s free Password Strength Checker analyses any password you type — measuring entropy in bits, estimating how long it would take to crack, and providing actionable tips. Best of all, the password never leaves your browser. This guide explains what makes a password strong and how to use the checker.
What makes a password weak?
Short length, missing character variety, and common words are the biggest culprits. An attacker using a dictionary attack or brute force can crack a simple 6‑letter lowercase password in seconds. Adding uppercase, numbers, and symbols expands the character pool and increases entropy exponentially. The checker estimates crack time based on a billion guesses per second scenario — a conservative estimate of modern hardware.
- See in real‑time how adding a single character boosts security.
- Understand “entropy” — the mathematical measure of randomness.
- Get specific tips like “add uppercase letters” or “use symbols”.
Step‑by‑step: check your password
- Open the Password Strength Checker tool.
- Type any password into the field. The strength bar changes colour and width.
- Read the entropy bits and estimated crack time. The tool also lists improvement tips if the password is weak.
- Try variations — add a symbol or lengthen it — and see the meter jump. When ready, generate a strong password with our Password Generator.
How the checker calculates crack time
It estimates the character pool size (lowercase = 26, +uppercase = 52, +digits = 62, +symbols = 94). Entropy = length × log2(pool). Then it divides 10^9 guesses/second into 2^entropy possibilities to give a time estimate. This is a simplification — real‑world attacks use smarter algorithms — but it provides a useful relative measure.
Frequently Asked Questions
Does the tool store my password?
No, the analysis is entirely client‑side. The password is never transmitted or saved.
What’s a good entropy score?
Aim for at least 60 bits for strong security; 80 bits or more is excellent.
Can I test a password I already use?
Yes, but ensure you’re on a private, trusted device and never test on public computers.
Why does it say “centuries” for crack time?
That means even with massive computing power, the password would take impractically long to break by brute force.
What if I need a new strong password?
Use our Password Generator to create one with a click — it includes customisable length and character sets.
Try Password Strength Checker