The formula
The operating cycle is how many days your cash is tied up between paying for stock and getting paid by customers. Days inventory outstanding is average inventory divided by cost of goods sold, times 365. Days sales outstanding is average receivables divided by net credit sales, times 365. The cycle is the first leg plus the second. A cycle of 152.08 days means cash is tied up for 152.08 days between buying stock and collecting from customers.
Step 1 — Find the average inventory and cost of goods sold
Start with the average inventory, from the balance sheet. Average inventory is (opening inventory + closing inventory) ÷ 2. Then find the cost of goods sold, from the income statement. The inventory leg uses ONLY the cost of goods sold — never revenue, because revenue is what you sell, not what the stock cost you. On the worked example the average inventory is $150,000.00 and the cost of goods sold is $900,000.00.
Step 2 — Work out the days inventory outstanding
Divide the average inventory by the cost of goods sold, then multiply by 365: how many days the stock on hand lasts at the current selling rate. On the worked example it is $150,000.00 ÷ $900,000.00 × 365 = 60.83 days. That is the first leg: cash sits in stock for 60.83 days before the stock is sold.
Step 3 — Find the average receivables and net credit sales
Now find the average receivables, from the balance sheet. Average receivables is (opening receivables + closing receivables) ÷ 2. Then find the net credit sales, from the income statement. The receivables leg uses net credit sales ONLY — never total revenue, because cash sales are already collected. On the worked example the average receivables are $300,000.00 and the net credit sales are $1,200,000.00.
Step 4 — Work out the days sales outstanding
Divide the average receivables by the net credit sales, then multiply by 365: how long, on average, a dollar of credit sales waits before the customer pays it. On the worked example it is $300,000.00 ÷ $1,200,000.00 × 365 = 91.25 days. That is the second leg: cash sits in unpaid invoices for 91.25 days after the stock is sold.
Step 5 — Add the two legs
Add the two legs. On the worked example it is 60.83 + 91.25 = 152.08 days. That is the operating cycle: your cash is tied up for 152.08 days. There is no third leg to subtract — that comes later, when you turn the operating cycle into the cash conversion cycle by taking off what you owe suppliers.
Step 6 — Check the result
Retail often runs 30 to 60 days, manufacturing 60 to 120 days, construction longer. On the worked example the cycle is 152.08 days, so the business sits above the manufacturing line — long, and worth watching. A cycle near zero means customers pay almost as soon as the stock is sold, and the business barely waits for its cash at all.
Three worked examples
The headline example: $150,000.00 of average inventory, $900,000.00 of cost of goods sold, $300,000.00 of average receivables and $1,200,000.00 of net credit sales. The days inventory outstanding is 60.83 days, the days sales outstanding is 91.25 days, and the operating cycle is 60.83 + 91.25 = 152.08 days. The target example: how much stock must the business hold for a 100.00-day cycle. The average inventory needed is (100.00 − 91.25) × $900,000.00 ÷ 365 = $21,575.34. The reverse example: the smallest whole-dollar inventory for a 160.00-day cycle. It is $169,521; at $169,520 the inventory is $1 short of the $169,521 needed. Use the operating cycle calculator for your own numbers.
One reverse to check your answer
The smallest whole-dollar average inventory for the OC to reach 160.00 days is $169,521 — at $169,521 the cycle is 160.00 days; at $169,520 the inventory is $1 short of the $169,521 needed. The average inventory needed for a 100.00-day cycle is $21,575.34. If your own numbers give a cycle far from the one you expected, work the two legs separately: a wrong leg is usually a wrong input, and the most common mistake is using total revenue where the formula needs net credit sales.
What average inventory is, and why it is an average
Average inventory is (opening inventory + closing inventory) ÷ 2: the stock at the start plus the stock at the end, divided by two. A single snapshot misleads: a business that stocks up in December and sells through in January shows huge inventory in December and small inventory in February. The average is steadier, because stock levels swing through the year. The same averaging idea applies to receivables: use (opening + closing) ÷ 2 for both legs, and use the same period for the cost of goods sold and the net credit sales.
What a high cycle means — and what a low cycle means
A high cycle means cash is tied up in stock and unpaid invoices, and the business usually needs more working capital. A low cycle means cash comes back fast, and the business needs less working capital. A cycle near zero is the best of all — customers pay almost as soon as the stock is sold — but a cycle that is too short can mean stockouts, rushed orders and strained suppliers. The goal is a healthy cycle, not the shortest possible one. Compare within an industry, not across them: a retailer and a builder with the same cycle are in very different positions.
What to do when the cycle is long
A 152.08-day cycle means each dollar of costs takes about five months to come back as cash. Shorten it by attacking the longest leg first: on the worked example the days sales outstanding is 91.25 days, longer than the 60.83 days in stock, so collecting from customers faster is the quickest win. Tighten credit terms, offer early-payment discounts, and chase overdue invoices weekly instead of monthly. Then look at the stock leg: order just in time and clear slow-moving stock. The inventory the business must hold for a 100.00-day cycle is only $21,575.34 — far less than the $150,000.00 it holds now — which shows how much cash is sitting on the shelves.
How the operating cycle differs from the cash conversion cycle
The operating cycle is days inventory plus days sales: 60.83 + 91.25 = 152.08 days on the worked example. The cash conversion cycle is the operating cycle minus days payable: 152.08 − 73.00 = 79.08 days, where the 73.00-day gap is exactly the days payable outstanding. The operating cycle is always at least as long as the cash conversion cycle, because payables can only shorten the wait, never lengthen it. Days sales outstanding is one leg: it tests how fast customers pay you, and 91.25 days on the worked example. Inventory turnover is the stock leg in different units: it tests how many times a year the stock sells through. The operating cycle is the picture before suppliers are paid; the cash conversion cycle is the picture after. See the cash conversion cycle calculator and the guide to calculating the cash conversion cycle, and the guide to calculating days sales outstanding.