Perpetual inventory system updates inventory accounts after each purchase or sale.
Inventory subsidiary ledger is updated after each transaction. Inventory quantities are updated continuously.
Periodic Inventory System
Periodic inventory system records inventory purchase in "Purchases" account. "Purchases" account is updated continuously, however, "Inventory" account is
updated on a periodic basis, at the end of each accounting period (e.g., monthly,
quarterly)
Inventory subsidiary ledger is not updated after each purchase or sale of inventory.
Inventory quantities are not updated continuously. Inventory quantities are updated on a periodic basis.
Example:
Analyze transactions of the company A:
On May 1, 2014: Purchased 1,000 units of merchandise at $30 per unit on credit.