Go to the BP_MasterInventory then create a new function called CheckFreeSlotCount then add an Integer output called FreeSlots.

Then create a local variable called FreeSlotsL and set it to an Integer then copy the image below.

Next go to the BP_PlayerInventory and create a new function called PlayerInventoryFreeSlotCount and add an Integer output called FreeSlots.

Then create a local variable called FreeSlotsL and set it to an Integer then copy the image below.

The PlayerInventoryFreeSlotCount function can be used to count the number of empty slots in the players pockets and current equipment they are wearing.

The CheckFreeSlotCount can check a single inventories number of empty slots like a storage chest or a equipment inventory such as a backpack.