Password Strength Checker
Check password strength, calculate entropy bits, and estimate crack time based on length and character sets.
Run tool
The Password Strength Checker evaluates password candidate strings to help you analyze composition, pattern risks, and length benchmarks. When you type or paste text into the password field, the tool inspects character sets across lowercase letters, uppercase letters, numeric digits, and non-alphanumeric symbols. It awards higher score points as your input reaches thresholds of 8, 12, 16, and 20 characters, while giving credit for diverse character types. The scoring model simultaneously checks for structural flaws, applying deductions when three or more identical characters repeat in a row or when recognized three-character sequences appear. Common passwords from standard lists receive an immediate zero rating along with targeted advisory feedback. Alongside the final score spanning zero through seven and its categorical label from Very Weak to Perfect, the evaluation displays an estimated entropy value in bits and a crack time estimate calculated at one billion attempts per second.
Instructions
- Enter or paste your candidate password text into the password field.
- Run the check to evaluate length, character categories, and repeating patterns.
- Review the strength score, rating label, entropy estimate, crack time, and feedback.
Examples
- Evaluating 'Tr0ub4dor&3' detects uppercase letters, lowercase letters, numbers, and symbols, returning an estimated entropy calculation and a multi-year crack time estimate.
- Evaluating 'password123' identifies a recognized sequence and common phrase, assigning a score of 0 and providing feedback about predictable patterns.
FAQ
How is the strength score calculated?
The tool scores passwords from 0 to 7 based on reaching length milestones of 8, 12, 16, and 20 characters, mixed character types, and deductions for sequential characters or three consecutive repeating characters.
What does the estimated crack time represent?
The crack time estimates how long exhaustive guessing would take assuming a fixed testing rate of one billion guesses per second, formatted into readable units from seconds to centuries.
What happens if I submit an empty field?
An empty input produces an instant baseline evaluation with a score of zero, zero entropy bits, and no detected character types or feedback warnings.
Why does a long password still receive a low score?
Passwords that appear on common password lists or contain repeated characters and predictable numeric or alphabetical sequences receive penalties that reduce the final score.