Working capital explained: inventory, receivables and payables

Working capital is the money a business needs to fund its day-to-day operations: buying inventory, waiting for customers to pay, and paying suppliers. It sits between earning a sale and collecting the cash, and growth usually makes it larger. For investors, working capital explains why a profitable, growing company can still find itself short of cash.

Two definitions

The term is used in two slightly different ways.

Net working capital (accounting) = Current assets - Current liabilities

Operating working capital = (Accounts receivable + Inventory) - Accounts payable

The first, from the balance sheet, includes everything due within a year, including cash and short-term debt. It is a measure of liquidity. The second removes cash and debt-like items and focuses on the operating cycle: what customers owe, what is sitting in stock, and what is owed to suppliers. It is the version usually used in cash flow analysis and valuation, though analysts vary in whether to include items such as accrued expenses and deferred revenue.

The three moving parts

• Accounts receivable. Money customers owe for goods or services already delivered. Faster collection means less cash tied up.
• Inventory. Raw materials, work in progress and finished goods waiting to be sold. Lean inventory frees cash; bloated inventory ties it up and risks write-downs.
• Accounts payable. Money the company owes suppliers. Paying later keeps cash in the business longer, effectively a free loan from suppliers, though it cannot be stretched without limit.

Each is commonly measured in days:

Days sales outstanding (DSO)   = Receivables / Revenue x 365
Days inventory outstanding (DIO) = Inventory / Cost of revenue x 365
Days payables outstanding (DPO)  = Payables / Cost of revenue x 365
Cash conversion cycle = DIO + DSO - DPO

The cash conversion cycle summarizes how many days cash is tied up between paying for inputs and collecting from customers.

Example (illustrative numbers)

A company has annual revenue of $3,650 million, cost of revenue of $2,190 million, receivables of $450 million, inventory of $360 million and payables of $270 million.

• DSO = 450 / 3,650 x 365 = 45 days.
• DIO = 360 / 2,190 x 365 = 60 days.
• DPO = 270 / 2,190 x 365 = 45 days.
• Cash conversion cycle = 60 + 45 - 45 = 60 days.
• Operating working capital = 450 + 360 - 270 = $540 million.

Now suppose revenue grows 10% and the day counts stay the same. Each balance rises by about 10%, so operating working capital increases by roughly $54 million. That is a cash outflow, even though the company is growing and presumably profitable. It appears on the cash flow statement as a negative adjustment in operating cash flow. See operating cash flow vs net income.

How changes affect cash

Rapid growth therefore tends to absorb cash first and release it later. A shrinking business may do the opposite, releasing cash from working capital, which can flatter its cash flow temporarily even as sales decline.

How to read it

Rules of thumb:

• Look at days, not dollars. The dollar balances grow with sales. DSO, DIO and DPO show whether the company is getting slower or faster.
• Compare against revenue growth. Receivables or inventory rising much faster than sales can signal slow collections, weaker demand or stock that may need to be written down.
• Compare with peers. Grocers and restaurants can run with very little working capital. Equipment makers and industrial distributors usually need much more.
• Negative operating working capital is not always a problem. Businesses that collect from customers before paying suppliers, or that bill in advance, can have negative working capital that funds growth. See deferred revenue. The flip side is that if growth stalls, the funding benefit fades.
• Check liquidity separately. For short-term solvency, the current and quick ratios are the usual tools.

Common mistakes and limits

• Treating a low current ratio as automatically bad. Some strong businesses run low or negative working capital by design.
• Treating high working capital as safe. It may consist of slow-moving inventory or uncollectable receivables.
• Relying on year-end snapshots. Balances can be seasonal. A retailer's inventory peaks before the holiday season, so use averages or compare the same quarter across years.
• Overlooking one-off effects. Acquisitions, currency moves and changes in supplier terms alter working capital without reflecting underlying efficiency.
• Missing the manipulation risk. Pushing out supplier payments or selling receivables can improve cash flow in the short term without improving the business. Look for consistency over time.
• Ignoring definitions. Whether cash, debt or accrued items are included changes the figure, so use the same definition when comparing.
• Using ratio levels without context. Days inventory of 60 means different things for a grocer and a shipbuilder. See asset and inventory turnover.

Where to see it on StocksXray

Working capital items appear in the balance sheet and cash flow statement in the SEC filings linked from each stock page. Changes in working capital flow into operating cash flow and therefore into free cash flow.

Key takeaways

• Working capital is cash tied up in receivables and inventory, partly financed by payables.
• Net working capital measures liquidity; operating working capital measures the cash needed to run the business.
• DSO, DIO, DPO and the cash conversion cycle show how efficiently working capital is managed.
• Growth normally absorbs cash through working capital, so profitable companies can still face cash pressure.
• Judge changes against sales growth, peers and seasonality rather than the dollar balance alone.