Working Capital Explained: How Much a Business Really Needs

Working capital is the cash a business can actually put to work right now — and it is the fastest read on whether a company can survive the next 90 days without borrowing. Get it in one line: working capital = current assets − current liabilities. If that number is comfortably positive, the business can pay its bills. If it is thin or negative, you need to know why before you judge it.

Here is what most explainers get wrong. A negative number is not automatically a red flag. Some of the strongest companies on the planet — Amazon, McDonald's, Costco — deliberately run negative working capital, and it is a competitive weapon. This is working capital explained the way an analyst actually uses it: the formula, what positive versus negative really signals, and how much a business genuinely needs. If you want the full toolkit behind reading a balance sheet, our structured fundamental analysis course walks through every line.

What is working capital, in plain terms?

Working capital is what a company owns that will turn into cash within a year, minus what it owes within that same year. Current assets are cash, receivables (money customers owe) and inventory. Current liabilities are payables, accrued costs and short-term debt. Subtract one from the other and you have the buffer the business runs on day to day.

Think of it as the financial equivalent of the cash in your account after this month's bills are accounted for. A healthy buffer means the firm can fund payroll, restock shelves and ride out a slow quarter without reaching for a credit line.

The reason this matters to you as an investor is simple: profit is an opinion, but working capital is closer to a fact. A company can report strong earnings and still run out of cash if its money is locked inside unsold inventory and invoices no one has paid. That is what "what is working capital" really answers — can this business actually pay its way?

The word "current" is doing heavy lifting here. Accounting defines current assets and current liabilities as those expected to convert to cash, or fall due, within twelve months. So working capital is not a measure of long-term wealth — a company can own a billion-dollar factory and still be short on working capital if its near-term bills outrun its near-term cash. It is a timing measure, and timing is what kills otherwise profitable businesses.

The working capital formula (with a worked example)

The working capital formula never changes: current assets − current liabilities. What changes is what sits inside each bucket. Let's run a concrete example so the number stops being abstract.

Take a mid-sized retailer, "Northgate Supply." On its balance sheet it holds $0.40m in cash, $0.60m in receivables and $1.40m in inventory — $2.40m of current assets. Against that it owes $1.60m in current liabilities. Working capital is $2.40m − $1.60m = +$0.80m, and its current ratio is 2.40 / 1.60 = 1.5.

What to do with this: notice that $1.40m — more than half of Northgate's current assets — is inventory. That is working capital in the least liquid form there is. If those goods stop selling, the cushion evaporates even though the balance-sheet number still looks positive. Always ask what the working capital is made of, not just what it totals.

There are only two levers that move this number. A company can change its current assets — collect invoices faster, carry less stock, hold more cash — or it can change its current liabilities, chiefly by negotiating longer time to pay suppliers. Every working-capital improvement you will ever read about in an annual report is one of those two moves. The best-run companies pull both at once, and that is exactly how they engineer the negative working capital we look at next.

Positive vs negative working capital: which is better?

The honest answer: it depends entirely on the business model. Positive working capital is the default expectation and the safer read for most companies. Negative working capital — where current liabilities exceed current assets — sounds alarming but can signal a dominant, cash-generative operator. The table below is how to tell them apart.

The rule of thumb: positive working capital that keeps growing faster than sales is often a warning, not comfort — it usually means receivables or inventory are piling up. Negative working capital is only healthy when it comes from fast sales and long supplier terms, never from a company that simply cannot pay.

Why strong companies run negative working capital

This is the counter-intuitive part. When you buy on Amazon, the cash leaves your account the instant you click "Buy Now." Amazon then pays many of its suppliers 60 to 90 days later. For that gap, it is holding billions of your dollars — and financing its own operations with supplier money, interest-free.

That is why Amazon's cash conversion cycle was roughly -37 days in fiscal 2024: it collects from customers well over a month before it settles with suppliers. McDonald's and Costco run the same playbook. Negative working capital here is not distress — it is leverage over the supply chain that a weaker competitor could never negotiate.

Source: PwC Working Capital Study 24/25; Amazon fiscal 2024 filings via DiscoverCI.

What this means for you: before you flag a negative number, check the direction of the cash. If customers pay first and suppliers wait, negative working capital is a sign of pricing power. If the business is negative because it simply owes more than it owns and cannot sell its stock, that is the danger zone.

The cash a company frees from working capital does not vanish — it funds growth, buybacks or dividends without a single new loan. That is why the PwC figure matters: the €1.56 trillion sitting idle across public companies is money that could be reinvested if those firms collected faster and cleared inventory quicker. A business steadily shrinking its working-capital needs is, in effect, giving itself an interest-free credit line that grows with the company.

How much working capital does a business actually need?

There is no single "right" number, because the requirement is set by how fast money moves through the business. The tool analysts use is the cash conversion cycle (CCC): how many days cash is tied up between paying for stock and collecting from customers.

The formula is CCC = days inventory outstanding + days sales outstanding − days payable outstanding. A short or negative cycle means the business needs very little working capital because it is barely out of pocket at any moment. A long cycle — slow-selling inventory and slow-paying customers — means it needs a large buffer just to keep the lights on.

Put numbers on it. Suppose Northgate holds stock for 40 days before selling it, collects from customers 5 days after the sale, and pays its own suppliers 50 days after buying. Its cash conversion cycle is 40 + 5 − 50 = −5 days. Even a small positive working-capital balance is plenty here, because the business is cash-positive on timing alone. Now stretch inventory to 90 days and customer payment to 45, while suppliers still want paying in 30: the cycle balloons to 105 days, and the same company suddenly needs a far larger buffer to bridge the gap. Same business, same product — only the timing changed, and the working-capital requirement more than doubled.

Why the buffer keeps growing across the market

The trend is not in companies' favour. PwC found that global days sales outstanding rose 6.6% over the last five years, meaning customers are paying slower and more cash is stuck in receivables. For the most cash-intensive sectors, net working capital sat at 69.2 days in 2024, barely changed from 68.3 days back in 2015 — the pressure never really eased.

The practical guide: a business needs enough working capital to cover its cash conversion cycle plus a margin for a bad quarter. A company shortening its CCC is freeing cash; one whose CCC is lengthening is quietly consuming it, even if profits look fine.

Working capital vs the current ratio: what's the difference?

Working capital is an absolute dollar figure; the current ratio is the same idea expressed as a proportion. Working capital tells you the size of the buffer ($0.80m for Northgate); the current ratio (current assets ÷ current liabilities, or 1.5) tells you how many times over the company can cover its short-term bills.

Use them together. A $50m working-capital cushion sounds huge until you learn the company has $500m of current liabilities — a current ratio of 1.1, dangerously thin. The dollar number alone hides that; the ratio exposes it. For the sharper liquidity read, our breakdown of the current ratio versus the quick ratio shows when to strip inventory out of the calculation entirely.

Mistakes investors make when reading working capital

• Reading the total, ignoring the mix. Positive working capital stuffed with stale inventory is weaker than a smaller buffer held in cash.
• Treating negative as automatically bad. For a fast-inventory retailer, negative working capital is often the sign of a dominant business, not a failing one.
• Missing the trend. A single snapshot tells you little. Working capital ballooning faster than revenue usually means receivables or inventory are building up unsold — a classic warning covered in our guide to financial-statement red flags.
• Confusing working capital with cash generation. Cash released from working capital shows up in the cash flow statement; our explainer on free cash flow connects the two.
• Comparing across industries. A software firm and a supermarket have completely different working-capital needs. Only compare a company to its own history and its direct peers.

Frequently asked questions

This article is educational content, not investment advice. Company financial figures change each reporting period — always verify against the latest filings before making decisions.