If no PIM value is specified, VeraCrypt will use the default parameters used in versions prior to 1.12 for PBKDF2-HMAC (see Header Key Derivation). For Argon2id, default parameters are equivalent to PIM = 12:

• PBKDF2-HMAC defaults:
  • For system partition encryption (boot encryption) that uses SHA-256, BLAKE2s-256 or Streebog, 200000 iterations are used which is equivalent to a PIM value of 98.
  • For system encryption that uses SHA-512 or Whirlpool, 500000 iterations are used which is equivalent to a PIM value of 485.
• For non-system encryption and file containers, all derivation algorithms will use 500000 iterations which is equivalent to a PIM value of 485.
• Argon2id defaults: Memory Cost = 416 MiB, Time Cost = 6 iterations (equivalent to PIM = 12) //

The PIM minimal value for short passwords is 98 for system encryption that doesn't use SHA-512 or Whirlpool and 485 for the other cases. For password with 20 characters and more, the PIM minimal value is 1. In all cases, leaving the PIM empty or setting its value to 0 will make VeraCrypt use the default high number of iterations as explained in section Header Key Derivation.