Every owner wants the benchmark number. But a shop's gross margin is really two margins in a trench coat, and the split plus the trend will tell you more than any industry average ever will.
Type this question into a search engine and you will find a dozen confident answers, most of them different, none of them showing their work. That is not because the industry is hiding the number. It is because the question, asked as a single blended percentage, does not have one honest answer. Gross margin for a repair shop depends on your parts-to-labor mix, whether you sell tires, how your bookkeeper defines cost of goods sold, and what market you operate in.
So instead of handing you an unsourced benchmark, this piece shows you how the number is actually built, why it moves, and which comparisons are valid. Those turn out to be far more useful than a target you cannot verify.
A repair shop sells two things: technician hours and parts. Labor gross margin is what remains of labor revenue after technician cost. Parts gross margin is what remains of parts revenue after what the supplier charged you. Labor normally carries the stronger margin of the two; parts are a markup on a real invoice, and the market caps how far that markup can go.
Your blended gross margin is just the weighted average of those two numbers, weighted by mix. That has an important consequence: the blended number can move without either margin changing.
Here is a simplified, illustrative example. Same shop, two months. Labor margin stays at 62%, parts margin stays at 40%. The only thing that changes is the mix of work.
| Line | Labor-heavy month | Parts-heavy month |
|---|---|---|
| Labor revenue | $65,000 | $45,000 |
| Parts revenue | $40,000 | $60,000 |
| Labor margin | 62% | 62% |
| Parts margin | 40% | 40% |
| Blended gross margin | 53.6% | 49.4% |
Four points of blended margin gone, and nothing is wrong. Nobody discounted, no supplier raised prices, no technician slowed down. The shop just did more parts-heavy work that month. If you only watch the blended number, you will chase ghosts in months like this, and worse, a real margin problem can hide behind a favorable mix shift in the other direction.
Never diagnose from the blended margin. It is a scoreboard, not a gauge. The gauges are labor margin, parts margin, and mix, read separately. If your P&L cannot show you those three, fix the P&L first: here is how a shop P&L should be structured.
Labor margin has two moving parts: what you realize per billed hour and what a technician hour costs you.
Industry benchmarks have a definitional problem: you rarely know whether the shops behind the average book technician pay in COGS the way you do, include tires the way you do, or share your mix. Comparing your 53% to someone else's 58% may be comparing two different formulas. Two comparisons do not have that problem:
1. You versus you, over time. Your own books hold their definitions constant. A three-point slide in labor margin over two quarters is a real signal regardless of what any benchmark says, and it is the kind of slide that costs a full quarter when it is caught late (we walked through that math in how multi-shop groups catch a sliding location early).
2. Your shops versus each other. If you own several locations, you have something better than a benchmark: a peer group with identical accounting definitions, the same ownership, and comparable markets. When Shop 3 runs labor margin six points below its sisters, that is not a definitional artifact. That is a real gap with a findable cause, usually realization or a pay plan. Ranking locations this way is its own discipline, covered in which of your shops is actually most profitable.
None of this works if computing the split margins per location takes your bookkeeper three weeks. The point of the read is speed: margin by shop, split by parts and labor, same definitions, every month, without anyone assembling anything. That is precisely the consolidated view FinLoom's Multi-Shop tier maintains across every location, with weekly checks that flag a shop whose margin moves before the quarter absorbs it.
FinLoom puts every location's gross margin on one page, trended, side by side, with weekly alerts when one compresses. Import from QuickBooks, Xero, or straight from Mitchell and Omnique. White-glove setup in 4 weeks.
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