The Founder's Guide to Reading a Profit and Loss Statement

The structure

A P&L has three main sections: revenue at the top, expenses in the middle, and profit (or loss) at the bottom. Revenue is what you earned. Expenses are what you spent to earn it. The difference is your profit. That's the simple version. The nuance is in how revenue and expenses are categorised, and what the relationships between those categories tell you.

A P&L statement has a standard structure: revenue at the top, costs to produce that revenue (COGS) next, gross profit after that, operating expenses below, operating income, then non-operating items like interest and taxes, ending with net income at the bottom. Each section answers a different question about business performance.

The order matters because it builds a layered view. Revenue tells you about demand. Gross profit tells you about production efficiency. Operating income tells you about the business as a whole before financing decisions. Net income tells you what actually grew or shrank the business in dollar terms. Reading them in order gives you context for each number.

Gross profit and why it matters

Gross profit is revenue minus the direct costs of delivering your product or service, what's called cost of goods sold or cost of revenue. If you're a service business, this typically includes the labour and tools directly used to serve clients. Gross profit margin, gross profit as a percentage of revenue, tells you how efficiently you're delivering your core offering. A 60% gross margin means for every dollar you bring in, you keep 60 cents after delivering the service.

Gross profit is revenue minus the direct costs of producing it. For a product company, that is materials, manufacturing labor, and shipping. For a SaaS company, it is hosting costs, customer support, and payment processing. Gross margin (gross profit divided by revenue) shows how much of each revenue dollar is left after producing what was sold.

High gross margin businesses have more room to invest in growth. A 70% gross margin business generates $70 of gross profit on every $100 of revenue. That $70 has to cover sales, marketing, engineering, G&A, and still leave profit. A 30% gross margin business has $30 to cover the same costs, which is much harder. Gross margin is often the most important single number in the P&L.

Operating expenses

Below gross profit come your operating expenses, the costs of running the business: salaries, software, rent, marketing, professional services. Subtract these from gross profit and you get your operating profit (EBITDA is a variation of this). This number tells you whether the business is generating more than it costs to run.

Operating expenses are the costs of running the business that are not tied to producing the product. Sales and marketing, research and development, general and administrative (G&A). These are the categories most founders spend the most time managing because they are the most controllable in the short term.

Each category tells a different story. Sales and marketing growing faster than revenue often means CAC is deteriorating. R&D growth tracks engineering hiring. G&A growth beyond a certain size signals bureaucracy. Good P&L review looks at each category as a percentage of revenue to see if any is drifting outside of expected ranges.

What to focus on each month

Three numbers matter most in a monthly P&L review: revenue trend (is it growing, flat, or declining?), gross margin trend (are you getting more or less efficient at delivery?), and operating expense growth relative to revenue growth. If expenses are growing faster than revenue, you need to understand why and whether it's intentional investment or drift.

Monthly P&L review should focus on three things: did revenue come in at plan, are margins holding, and did any expense line move unexpectedly. Start from the top and move down. Most months, the answer is "everything is within 5%" and the review is fast. The months where something moves meaningfully are where the commentary and investigation matter.

Avoid focusing only on net income. Net income can look fine because of offsetting moves higher in the P&L. Revenue up 10%, gross margin down 5%, operating expenses flat could produce the same net income as revenue flat, gross margin flat, operating expenses down 3%. These tell very different stories about the business. Always read the whole P&L, not just the bottom line.