The money that comes in the door isn't the money you keep. Confusing the two is one of the most expensive misunderstandings in small business. Ask an owner how the business is doing and you'll often hear a revenue number. It's the figure that feels like success — sales are up, the top line is growing. But revenue is only half the story. Revenue is what comes in; profit is what's left after the costs of expenses for running your business. A business can bring in more than ever and still keep less — or nothing at all. Revenue Is Scale. Profit Is What's Left. Revenue is your total income before a single expense is subtracted — the top line. Profitability is what remains after all of your costs. Subtract the cost of what you sell and you have gross profit; subtract the rest of your operating expenses, taxes, and interest and you reach net profit, the bottom line. It's most useful as a margin: at a 20% net margin, you keep twenty cents of every dollar you bring ...