Generate Numbers Only Password

An 8-character mixed password with 95 possible characters has about 52 bits of entropy. To match this with digits only (10 possible characters), you would need approximately 16 digits. Each digit provides only 3.3 bits of entropy compared to 6.5 bits for a mixed-character password.

Numeric-only passwords are required for ATM PINs, phone voicemail boxes, building access keypads, hotel room safes, some alarm systems, and certain legacy banking phone verification systems. Many IoT devices and smart locks also use numeric-only codes for simplicity.

Many modern systems block obviously weak PINs like 0000, 1234, and 1111. However, not all do. Always use a randomly generated numeric password rather than choosing one yourself, since humans tend to pick patterns and dates that attackers check first in dictionary attacks.

Most online services require at least one letter in addition to numbers, so a purely numeric password will not be accepted. If a service does accept numbers only, it is a sign of poor security practices on their part. Use mixed characters whenever the system allows it.