Revenue rank and profit rank are two different lists, and in most businesses they don't match. The line that brings in the most money is often not the line that keeps the most of it. Until you've seen margin by service line, you're steering by the wrong list.
What is margin by service line?
It's simply how much each product or service keeps, not just how much it brings in. Take each line and write down two numbers: what it billed, and what it kept after the direct costs of delivering it, including the labor hours behind it. The second number as a percentage of the first is that line's margin.
I often see something like this:
| Service line | Billed | Margin | Kept |
|---|---|---|---|
| Retainers | $45,000 | 54% | $24,300 |
| Projects | $28,000 | 33% | $9,240 |
| Hourly | $11,000 | 18% | $1,980 |
*Illustration only.* By revenue, retainers merely lead. By what actually stays in the business, retainers carry the whole company, and the hourly line, which feels like easy incremental money, keeps less than a fifth of what it brings in.
Why owners rarely see this
The P&L most owners receive shows costs in categories, payroll, materials, software, not attached to the work those costs delivered. So the statement is accurate and the question stays unanswered. Getting the answer means allocating the direct costs of each line to that line. Start by estimating your hours per line last month, even if you have to reconstruct it from your calendar, then attach the materials and subcontractor costs that clearly belong to each. This is directional, not accounting-grade precision, and that's fine. Rough allocation beats no allocation. You're looking for the shape, and the shape is usually unmistakable.
What to do with a leaky line
When a line turns out to keep very little, you have four honest options: raise its price, reduce its delivery cost, restructure it into a better shape (hourly work converting to a retainer is the classic move), or retire it and give its hours to a line that earns more. What I'd caution against is the fifth option most owners pick by default, which is doing nothing because the line is familiar. Familiar is not the same as profitable, and every hour spent on an 18-cent line is an hour unavailable to a 54-cent one.