The values that KIS historically used were chosen for convenience, given there was no big choice in the containers. It's now time to fix the situation. In nutshell, the outer volume of the containers should be defined via the geometrical size of the part vs assigning an arbitrary "convenient" size via the volume override. And maximum inventory volume must be a slightly less value of the outer volume. Also, the mass of most KIS parts should decrease, assuming their scale and aluminum as material.

Here are the new values, calculated from the real world physics:

• SC-62 Portable Container
  • Mass: 100 kg => 10 kg
  • Inventory volume: 1000 L => 280 L
• SM-62 Container Mount
  • Mass: 25 kg => 5 kg
• ILC-18k Container
  • Mass: 1.5 t => 500 kg
  • Inventory volume: 18000 L => 8800 L
• ISC-6K Container
  • Mass: 500 kg => 300 kg
  • Inventory volume: 6000 L => 3900 L
• Kerbal's inventory:
  • Inventory volume: 300 L => 110 L

In order to rollback the new behavior to the legacy values, find file kis_legacy_containers.txt in the KIS installation and rename it to kis_legacy_containers.cfg. Keep in mind that this file will not be kept in the release for long. So either copy it into a safe location or simply get used to the new limits.