Cash Flow and Business Finance

It is tempting to think that a business making a profit is safe and one losing money is failing, but both ideas can mislead. Profit is an accounting summary of a period — revenue earned minus costs incurred, whether or not the money has actually moved. Cash is the real balance in the bank on a given day, and it is cash that pays wages, rent, and suppliers this month. Because money owed and money paid arrive on different schedules, a company can report a healthy profit and still be unable to meet Friday's payroll. Reading both numbers, and seeing where they diverge, is one of the most practical financial skills a founder or manager can hold, and it is the difference between a business that is genuinely healthy and one that merely looks hopeful on a spreadsheet.

Profit on paper is not cash in the bank

When you make a sale, the profit is often recorded the moment the deal is agreed, but the cash may not arrive for weeks. Meanwhile your own bills fall due on their own timetable. A firm can be profitable across a year yet spend long stretches with almost nothing in the account, simply because money goes out before it comes in. Profit tells you whether the model works; cash tells you whether you survive long enough to find out.

Runway and working capital

Runway is how many months a business can keep operating before its cash runs out. Hold 60,000 pounds and spend 10,000 more than you earn each month, and you have roughly six months of runway. Working capital is the everyday money tied up in operating — cash customers owe you, stock on the shelves, and bills you owe suppliers. When customers pay slowly while suppliers demand payment quickly, cash grows tight even as sales rise.

Unit economics

Unit economics asks a blunt question: does a single sale make money once you count everything it costs to deliver? If each order costs more to fulfil than the customer pays, growth makes the losses larger, not smaller. A business with sound unit economics earns more on each sale than that sale consumes; without them, it is buying revenue at a loss and hoping scale will fix arithmetic that only worsens.

A design studio lands a 40,000-pound project in March and records the profit that month. The client pays in June. But the studio's staff, software, and rent — say 12,000 a month — must be paid in March, April, and May regardless. On paper the studio is thriving; in practice it needs 36,000 pounds of cash to bridge three months before the invoice clears. If that cash is not there, a profitable project can sink the firm.

Cash can flatter too. A gym that collects a year of membership fees upfront in January holds a full account while having barely earned any of it — most of that money is owed back as service across the coming months. A founder who mistakes that early cash for profit and spends it will watch the account drain all year with no new income to replace it. Healthy cash today is not the same as money truly earned.

Analyses of why startups fail — the widely cited post-mortem collections compiled by CB Insights among them — repeatedly place running out of cash and failing to raise more near the top of the list, alongside building something the market did not want. These are self-reported, overlapping reasons rather than controlled findings, so treat the exact rankings with caution. The durable pattern is well documented, though: many businesses that closed were not absurd ideas run by careless people. They ran out of money before the model could prove itself, often while still reporting a notional profit.

• "Profit means we are safe." Profit is an accounting figure; an empty account ends the business regardless.
• "Growing sales fixes cash problems." If unit economics are negative or customers pay late, growth drains cash faster.
• "Cash in the account is profit." Money collected in advance is often owed back as future service.
• "Runway only matters to startups." Any business with uneven income needs to know how long its cash lasts.

Adjust a small firm's cash in, cash out, and payment timing, then watch how many months of runway remain. Find the point where a profitable month still empties the account.

Think Like a Maester: Profit is an opinion about a period; cash is a fact about a day. Businesses die on the days, not the periods.

1. In one sentence, how does profit differ from cash?
2. What is runway, and how would you estimate it?
3. Explain how a profitable business can fail to pay its staff.
4. What does it mean for a sale to have negative unit economics?
5. Why can a full bank account from upfront payments be misleading?

Profit and cash answer different questions: profit asks whether the model earns more than it spends over a period, while cash asks whether there is money in the bank to meet today's obligations. The gap between them — created by the timing of money in and out, the working capital tied up in daily operations, and the unit economics of each sale — is where otherwise healthy businesses quietly fail. Watching cash and runway as closely as profit is what keeps a good idea alive long enough to work.

• Revenue, Cost and Profit
• Finance