The three numbers everything else is built on, and the difference between the money that comes in and the money you keep.
10 min read · Level 1
Founders quote revenue because it is the number that sounds like success, and experienced people immediately ask about margin because revenue tells you nothing about whether the business works. A million in revenue against one-point-four million in costs is worse than two hundred thousand against a hundred and fifty. The four-line structure below is the whole of company finance; everything else is detail hanging off it.
Revenue is everything customers paid you. The top line.
Subtract COGS — the direct cost of delivering what you sold — and you get gross profit.
Subtract operating expenses — salaries, rent, software, marketing — and you get operating profit. If that number is negative, you made a loss.
That is the whole structure. Everything else in company finance is detail hanging off these four lines.
Because founders quote revenue and investors immediately ask about margin — and if you cannot answer, the conversation is effectively over.
More practically: revenue tells you nothing about whether the business works. A company with $1M of revenue and $1.4M of costs is in worse shape than one with $200k of revenue and $150k of costs.
A SaaS company in March:
Revenue — $40,000
COGS (hosting, payment fees, support) — $8,000
Gross profit — $32,000 (80% margin)
OpEx (salaries, rent, tools, marketing) — $55,000
Operating profit — −$23,000
Strong gross margin, and still losing $23,000 a month. That combination is completely normal for a growing startup — and it is exactly why runway matters more than revenue.
First-time founders often put everything into one bucket called 'expenses'. That hides the most important question in the business: does each sale make money before overheads?
The split matters because COGS and OpEx behave differently. COGS rises automatically as you sell more. OpEx is a decision you make.
Only money actually earned from customers. Not investment, not loans — those are financing, not revenue.
Hosting, per-seat API costs, payment processing, direct support. These are COGS: sell twice as much and they roughly double.
Salaries, rent, tools, marketing, legal. These do not move automatically when you make one more sale.
Revenue − COGS = gross profit. Gross profit − OpEx = operating profit. Write both down.
High gross margin with an operating loss means the model works and you are investing in growth. Low gross margin means the model itself needs fixing, and no amount of scale rescues it.
Monthly, for ever. It is the base layer of every other financial conversation you will have.
Do not spend time perfecting the split before you have revenue. Pre-revenue, the only number that matters is what you are spending.
A recognisable shape in early e-commerce and agency businesses: impressive top-line growth, celebrated internally and externally, sitting on a gross margin in the low twenties. The company needed roughly four times the revenue of a software business to fund the same team, and nobody had made that comparison explicitly.
Never quote revenue without knowing the margin behind it. The pair is the fact; the single number is a headline.
The most common bookkeeping shortcut is a single cost category. It hides the only question that matters early — whether each sale makes money before overheads — and it cannot be fixed retrospectively without re-categorising every historical transaction by hand.
Split costs into those that rise per sale and those that do not, from your first month. It is the split every useful metric depends on.
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