PIN Strength Checker Form
Example Data Table
These are sample values for demonstration only. Do not reuse them.
| Sample PIN | Length | Detected Notes | Score | Rating |
|---|---|---|---|---|
| ••34 | 4 | Below policy length, Common PIN list match, Sequential run detected, Keypad walk detected | 0/100 | Very Weak |
| ••80 | 4 | Below policy length, Common PIN list match, Keypad walk detected | 0/100 | Very Weak |
| ••78 | 4 | Below policy length, Date-like structure | 28/100 | Weak |
| ••••51 | 6 | Keypad walk detected | 58/100 | Moderate |
| ••••90 | 6 | Repeated block pattern, Keypad walk detected, Low digit uniqueness | 0/100 | Very Weak |
| ••••••42 | 8 | Keypad walk detected | 74/100 | Strong |
Formula Used
This calculator combines entropy, uniqueness, transition variety, and structured-pattern penalties. It estimates both brute-force exposure and common predictability mistakes.
Search Space: 10^L, where L is PIN length.
Raw Entropy: H = L × log2(10)
Uniqueness Ratio: U = unique digits / L
Transition Ratio: T = unique step changes / max(L - 1, 1)
Entropy Score: min(60, (H / 40) × 60)
Uniqueness Score: min(20, U × 20)
Transition Score: min(20, T × 20)
Final Score: clamp(0, 100, Entropy Score + Uniqueness Score + Transition Score - Penalties + Bonus)
Average Guess Time: (10^L / 2) / guess rate
Penalties are added for short length, common PIN matches, repeated digits, repeated blocks, sequential runs, keypad walks, low uniqueness, mirrored patterns, and date-like values.
How to Use This Calculator
- Enter a numeric PIN in the analysis field.
- Set the minimum policy length you want to enforce.
- Adjust uniqueness, sequence, and date-detection settings if needed.
- Provide online and local guess rates for your risk model.
- Press Check PIN Strength to generate the score.
- Review the detected patterns, estimated attack times, and improvement steps.
- Use the Plotly chart and export buttons for reporting.
FAQs
1) What makes a PIN strong?
A strong PIN is longer, uses more distinct digits, avoids dates, sequences, repeated chunks, and keypad paths, and does not appear on common-PIN lists.
2) Why is a four-digit PIN usually weak?
A four-digit PIN has only 10,000 combinations. That space is small, and many people choose obvious values like years, repeated digits, or ascending runs.
3) Does entropy alone decide strength?
No. Entropy estimates brute-force space, but humans pick patterns. This checker also penalizes sequences, keypad walks, date-like values, and popular PINs.
4) Why are birthdays and years risky?
Attackers often try personal dates early because they are memorable and widely reused. A year or date format can collapse real-world guessing effort.
5) What is a keypad walk?
A keypad walk follows nearby keys such as 2580 or 159. These shapes are easy to remember, easy to observe, and common in user-chosen PINs.
6) Why compare online and local guess rates?
Online systems often throttle attempts, while local attacks can be far faster. Seeing both helps you understand best-case and worst-case exposure.
7) Should I display my real PIN in results?
Only on a trusted personal device. Masking is safer, especially when screens are shared, recorded, or visible to people nearby.
8) What score should I aim for?
Aim for Strong or Very Strong. In practice, random six-to-eight digit PINs with no visible patterns are far better than memorable four-digit choices.