The Problem With Human-Chosen PINs
Analyses of leaked PIN databases show staggering concentration: about 1 in 10 four-digit PINs in the wild is 1234, and the twenty most common choices (1111, 0000, 1212, birth years…) cover more than a quarter of all PINs in use. A thief who finds a wallet with a card and a driver's license will try birthdays first — and statistically, they'll often be right. A random PIN removes every one of those shortcuts.
When you have the choice, prefer 6 digits over 4: it multiplies the search space from 10,000 to 1,000,000, which matters most on devices that don't aggressively lock out attempts.
PIN Safety Basics
Use a different PIN for each card and device, never store a PIN in the same wallet or phone case as the card it protects, and shield the keypad with your other hand at ATMs and checkouts — hidden cameras aimed at keypads remain the most common skimming companion. If a bank assigns you a PIN and lets you change it, change it to a random one, not a memorable date.