PIN Security: 4-Digit vs. 6-Digit PINs
Last Updated: May 19, 2026
A personal identification number (PIN) is a numeric code used to verify user identity and control access to systems and devices. Choosing the right PIN length is an important part of a secure print environment — shorter PINs are faster to enter but are significantly more vulnerable to brute-force attacks.
Key Points
- A 4-digit PIN has 10,000 possible combinations, while a 6-digit PIN has 1,000,000 — 100 times more.
- Automated tools can cycle through all 4-digit combinations in minutes. The same attack against a 6-digit PIN can take days or weeks.
- Common PINs like 1234, 0000, and 1111 are among the most frequently chosen combinations, and automated attacks typically start with these. Avoiding predictable sequences is as important as PIN length.
- For most enterprise environments, a PIN length of 6 to 8 digits offers a good balance of usability and protection.
How It Works
The primary threat to numeric PINs is brute-force attack, where an automated tool attempts every possible combination in sequence. As the number of possible combinations increases, the time required to perform an exhaustive brute-force attack increases proportionally.
To directly increase the time required for a successful brute-force attempt, increasing the length and randomness of a PIN is the most effective control. A 4-digit PIN offers a relatively small attack surface for modern automated tools. A 6-digit PIN expands that surface 100-fold, making attacks significantly less practical, particularly in environments without hardware lockout mechanisms.
It's worth noting that PIN length alone does not guarantee security. Users tend to favor certain combinations, meaning the theoretical advantage of 6-digit PINs is reduced when users choose predictable patterns like 123456 or repeated digits. A randomly selected 6-digit PIN is meaningfully more secure than a patterned one.
Requirements
- Use a minimum 6-digit PIN wherever the system supports it.
- Avoid sequences, repeated digits, or patterns based on personal information such as birthdates.
- Where available, enable account lockout after a defined number of failed attempts to limit brute-force exposure.
Additional Resources
Refer to the following external resources for more information about PIN security standards: