What it means
Unlike modern digital setups that update automatically every time an item scans through a till, the periodic approach relies on a physical stocktake at set dates. During the accounting period, businesses record all purchases in a temporary purchase account.
When they want to know their profit or inventory value, staff physically count everything left on the shelves. This method is popular with smaller businesses because it is cheap and simple to set up.
You do not need expensive barcode scanners, specialized software, or constant database updates. You simply look at what you started with, add what you bought, and subtract what is physically left at the end to calculate your cost of goods sold.
The main drawback is the lack of real-time visibility. If a customer asks if an item is in stock mid-month, staff might have to check the shop floor rather than a computer screen.
Furthermore, because cost of goods sold is calculated in bulk at the end of the period, businesses cannot easily track losses from theft, damage, or administrative errors until the physical count reveals a discrepancy.
In practice
Real-world examples.
Example
A local bookstore counts its remaining novels on the last day of every month. By doing this physical check, the owner calculates how many books were sold and works out the monthly profit.
Example
A small hardware shop reviews its stock of nails and hammers once a quarter. This periodic count helps the manager prepare quarterly financial accounts without needing complex tracking software.
Example
A boutique clothing maker takes stock of fabric rolls twice a year. This schedule aligns with their tax reporting deadlines, keeping administration simple for the sole trader.
Think of it
“Imagine tracking your household groceries by looking in the pantry once a month rather than keeping a daily receipt log. You start with ten tins of soup, buy twenty more during the month, and find five left at the end, meaning you used twenty-five.
Formula
Calculation
Cost of Goods Sold (COGS) = Beginning Inventory + Purchases - Ending Inventory
Example:
- Beginning Inventory: 1,000 pounds
- Purchases: 5,000 pounds
- Ending Inventory (counted): 1,500 pounds
COGS = 1,000 + 5,000 - 1,500 = 4,500 poundsCase study
Seen in the real world.
Oak Furniture Emporium uses a periodic inventory system to manage its wooden tables and chairs. At the start of the financial year, the owner records an opening stock value of 20,000 pounds. Throughout the year, the business purchases an additional 50,000 pounds worth of inventory.
Because sales are not logged individually against stock items, the business has no exact digital record of inventory levels during the year. On the final day of the year, staff spend the evening physically counting every item in the warehouse. They determine that the ending inventory has a total cost value of 15,000 pounds.
To calculate the cost of goods sold for the annual accounts, the accountant applies the standard formula: 20,000 pounds beginning inventory, plus 50,000 pounds purchases, minus 15,000 pounds ending inventory, resulting in a cost of goods sold of 55,000 pounds. This figure is then matched against total sales revenue to find the gross profit. While this approach saved the business money on software setup costs, the owner notes that any stock theft or breakage during the year is hidden inside the final cost of goods sold figure, making loss prevention harder.
Watch out
Common mistakes.
- Assuming inventory levels shown in the accounts are up-to-date during the middle of an accounting period.
- Forgetting to include carriage costs paid on incoming stock purchases within the total purchase calculation.
- Failing to conduct an accurate physical count at the end of the period, which distorts both profit and tax figures.
Questions
People also ask.
Why would a business choose a periodic system over a perpetual one?
It is much cheaper, simpler to run, and requires minimal administrative effort, making it ideal for small shops with low transaction volumes.
How do you know what items were stolen or lost?
Under this system, you generally cannot track shrinkage easily because losses are simply lumped into the final cost of goods sold calculation.
Is this system compliant with standard accounting rules?
Yes, provided that a thorough and accurate physical inventory count is conducted at the end of every accounting period.
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