Read your P&L in one sitting
Your accountant sends you a P&L every month and you nod at it. This lesson is the five-line tour: revenue, cost of sales, gross profit, operating expenses, and net profit — what each one is really telling you, and the two ratios that turn the statement from paperwork into a dashboard.
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The five lines that matter
A P&L is subtraction stacked on subtraction. Revenue minus cost of sales is gross profit. Gross profit minus operating expenses is net profit. That's the whole machine — everything else is detail inside those buckets.
| Line | What it is | What it tells you |
|---|---|---|
| Revenue | Money from sales, before anything | Size of the engine — not health |
| Cost of sales | Direct cost of delivering the work | How expensive your product is to make |
| Gross profit | Revenue − cost of sales | The real money the business model makes |
| Operating expenses | Rent, software, insurance, admin | What it costs to keep doors open |
| Net profit | Gross profit − opex | What's left for you, taxes, and growth |
Gross margin: the one number to memorize
Gross margin is gross profit ÷ revenue. A 40% margin means every $1 of sales leaves 40 cents to pay the bills and you. Track it monthly. Falling margin with flat revenue means your delivery costs are creeping up (suppliers, subcontractors, your own unpaid hours hiding in 'cost of sales').
Nobody approves a margin decline — it happens one small raise at a time: a supplier +8%, an extra hour of polish, one un-billed change. Only the monthly margin ratio catches the pattern.
Opex: the line you actually control
Operating expenses move slowly and predictably — which is why they're the honest place to cut when needed. Review the list twice a year: every subscription, every insurance, every 'small' monthly fee. A $29 tool nobody uses is $348/year of someone's hourly wage.
- Fixed opex (rent, insurance): negotiate annually, not monthly.
- Variable opex (software seats, ads): re-justify every quarter — 'what does this earn?'
- Watch creep: new recurring tools should displace old ones, not stack.
Net profit: the truth, if the books are honest
The classic small-business lie is the owner's 'salary' hiding inside expenses (or not in the books at all). Net profit only means something when your own pay is a real line. Profit after paying yourself a market wage is the only number that says whether the business is a business.
Read the P&L like a dashboard, not a report card — trends and ratios first, story later.
The JK23 Ledger Letter, issue 3
Frequently asked questions
How is this different from my bank balance?
The bank balance is cash at one moment — the P&L is performance over a period. You need both: cash tells you if you can pay Friday's payroll; the P&L tells you whether the model works. (See our cash flow lesson for the first half.)
What's a 'good' net margin?
Depends entirely on the industry — a grocery store at 2% and a software consultancy at 20% can both be healthy. Compare to your own history and your sector's typical range, not to a universal number.
Should owner pay be in expenses?
Yes — as a salary line if you pay yourself regularly, or as an owner draw noted separately. Books that hide owner compensation make the business look better than it is, usually to the owner's own detriment.