What it means
The measure has three parts: days inventory outstanding, days sales outstanding and days payable outstanding. The first two represent cash going out and staying out, while the third represents cash the business is allowed to hold on to a little longer.
It matters because growth consumes cash. A company that has 70 days of working capital tied up needs roughly ten weeks of trading funded before it sees a return, so doubling revenue can create a serious funding requirement even while the business is profitable.
In practice each component is calculated by dividing the relevant balance sheet figure by an average daily flow. Receivables and revenue for collection days, inventory and cost of goods sold for stock days, and payables and cost of goods sold for payment days.
Improving the figure is one of the cheapest sources of funding available. Taking ten days out of the cycle in a business turning over $18,000,000 a year releases roughly half a million dollars of cash permanently, with no interest to pay and no equity given away.
The nuance is that not every reduction is good. Stretching suppliers too far damages relationships and can cost more in lost discounts than it saves in interest, and cutting stock too hard shows up as lost sales rather than as an improved ratio.
In practice
Real-world examples.
Example
A hardware retailer cuts slow-moving lines and reduces days inventory outstanding from 75 to 55. With daily cost of goods sold of $20,000, that releases $400,000 of cash which funds two new store fit-outs without borrowing.
Example
A staffing agency has almost no inventory but 52 days sales outstanding against 7 days payable outstanding, because contractors are paid weekly while clients pay monthly. Net working capital days of 45 explains why the agency needs an invoice finance facility to grow.
Example
A supermarket sells stock in about 20 days, collects from card customers within 2 days and pays suppliers in 45. Net working capital days of negative 23 means suppliers fund the business, which is why expansion needs little working capital.
Think of it
“Working capital days shows how long cash is tied up in operations-your cash cycle length.
Formula
Calculation
Net Working Capital Days = Days Inventory Outstanding + Days Sales Outstanding - Days Payable Outstanding, where each component divides the balance by the relevant daily flow.
A specialist equipment distributor has annual revenue of $18,250,000 and cost of goods sold of $10,950,000. That gives daily revenue of $18,250,000 / 365 = $50,000 and daily cost of goods sold of $10,950,000 / 365 = $30,000.
Average accounts receivable is $2,250,000, so days sales outstanding = $2,250,000 / $50,000 = 45 days.
Average inventory is $1,800,000, so days inventory outstanding = $1,800,000 / $30,000 = 60 days.
Average accounts payable is $1,050,000, so days payable outstanding = $1,050,000 / $30,000 = 35 days.
Net working capital days = 60 + 45 - 35 = 70 days. In balance sheet terms, net working capital is $2,250,000 + $1,800,000 - $1,050,000 = $3,000,000 of cash locked in the trading cycle.Case study
Seen in the real world.
This illustrative story features Halverton Instruments, a fictional distributor of laboratory equipment. Revenue grew from $12,000,000 to $18,000,000 in two years, profit stayed healthy, and yet the overdraft was permanently at its limit.
The finance director calculated net working capital days and found 82: stock was sitting for 68 days because the sales team wanted every item available immediately, customers were taking 49 days against 30 day terms, and suppliers were being paid in 35 days to secure early settlement discounts that were worth less than the interest cost.
Over a year Halverton cut stock days to 52 by agreeing consignment terms on the slowest lines, brought collection days to 38 with earlier reminders and monthly statements, and moved suppliers to 45 day terms after dropping the settlement discounts. Net working capital days fell to 45, releasing roughly $1,800,000 of cash and clearing the overdraft entirely.
Watch out
Common mistakes.
- Calculating payable days on revenue instead of cost of goods sold, which understates the figure and makes the cycle look shorter than it is.
- Using a single year-end balance in a seasonal business, when a date chosen after the quiet period gives a flattering and misleading answer.
- Assuming a lower number is always better, when it can simply mean the business is out of stock or paying suppliers so slowly that terms are about to be withdrawn.
Questions
People also ask.
Is this the same as the cash conversion cycle?
Yes, the two names describe the same calculation, though some businesses include only trade balances in the working capital version.
Can the figure be negative?
Yes, and it is common in supermarkets and subscription businesses that collect from customers before paying suppliers, which is a genuine funding advantage.
How often should it be measured?
Monthly, using average balances rather than a single snapshot, so seasonal swings and one-off shipments do not distort the trend.
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