Model your repair shop's monthly profit by separating labor billings from parts markup — and see exactly what per-job profit looks like after rent, wages, and overhead.
Ask most shop owners what they made last month and they'll tell you the deposit total. Ask how much of it came from parts versus labor and you get a shrug — which is wild, because those are two completely different businesses sharing one lift. One sells your time at an hourly rate; the other quietly marks up an alternator 45% while you sleep. This calculator splits them apart. Enter Jobs Per Week, average labor per job, average parts cost per job, and your Parts Markup percentage, and you get a full income breakdown showing gross revenue from labor, gross parts margin, and net profit after rent, wages, and overhead.
The default inputs — 20 jobs per week, $200 average labor, $180 average parts at a 45% markup — represent a mid-volume independent shop. A shop at those inputs is billing roughly $15,600 in labor per month and generating about $5,600 in parts margin before expenses. Whether that $21,200 gross supports a profitable operation depends entirely on what's sitting in rent, wages, and overhead. Change those three numbers to yours and the model becomes real.
Parts markup: the margin line most shops underprice
At a 45% markup on $180 in parts per job, you're generating $81 in parts margin per vehicle. On 20 jobs per week, that's $1,620 per week — $6,994 per month — from parts alone. Many independent shops mark parts up only 30-35%, leaving $810-$1,080 per month in margin on the table relative to a 45% markup on the same volume. Before hiring another technician or raising labor rates, audit your parts markup against your actual supplier costs.
Dealerships and chains typically mark parts up 60-100% and use volume pricing with suppliers to protect their gross profit. Independent shops competing on labor rate often inadvertently subsidize their parts pricing too. The rule of thumb in the trade is that parts revenue should contribute 40-50% of total gross revenue; if it's below that, your markup rate is likely the issue rather than volume.
What the per-job profit number reveals
Per Job Profit is net profit divided by total jobs for the month. It answers a simple question: after paying all fixed costs, what does the shop average per completed repair? A shop netting $4,200 per month on 90 jobs is averaging $46 per job. A shop netting $4,200 on 60 jobs is averaging $70 per job — working less and making the same total because each job carries more margin.
This metric matters when evaluating whether to take low-value work. A tire rotation at $25 labor occupies a bay for 30 minutes and contributes almost no margin after parts and overhead allocation. Turning away routine maintenance at slow times to prioritize $400 transmission jobs improves per-job profit without requiring volume growth. Track this number quarterly and set a floor — say $40 per job as a minimum to even schedule — and let the calculator show you what that filter does to total monthly net.
The wage-to-revenue ratio and when it goes wrong
At $5,000 in wages and $2,500 in rent with $1,200 in overhead, a shop's fixed monthly cost is $8,700. At 20 jobs per week and a combined labor/parts gross of roughly $22,000, the shop has $13,300 in gross profit to cover those $8,700 in fixed costs and generate net income. Gross margin of 60% looks healthy — until job volume drops to 14 per week in a slow month and the $8,700 fixed cost base doesn't flex.
The risk point is when employee wages are sized for peak volume. If your shop does 22 jobs per week in summer and 12 in January, wages designed for summer output create a loss in winter. Modeling the calculator at your slowest realistic monthly volume — not your average — shows you the true floor of your profitability and whether your fixed cost base is sustainable through a seasonal trough.
Labor rate increases and what the math looks like
Raising your labor rate from $95/hour to $110/hour on a 2.1-hour average job increases average labor per job from $200 to $231. At 20 jobs per week, that's an additional $6,000/month in labor revenue on the same job count. If competitors in your market are at $100-$115/hour and you're still at $95, a rate adjustment may produce more total net than adding two jobs per week with the same cost structure.
The psychology of price increases is that customers notice the rate on the invoice. What they remember is whether the repair was done right the first time. Shops that hold below-market labor rates to compete on price often have the same customer retention problems as higher-priced shops, without the margin to invest in better tools or faster technicians. Run the calculator at your proposed new labor rate, confirm the per-job profit improvement, and use that number to evaluate whether the pricing conversation with existing customers is worth having.
Breakeven job count and seasonal planning
Your breakeven — the job count where gross profit exactly covers fixed costs — is straightforward to find using the calculator: reduce jobs per week until net profit reaches zero. At $2,500 rent, $5,000 wages, and $1,200 overhead with the default labor and parts inputs, breakeven falls around 12 jobs per week. That's the minimum sustainable operating pace. Anything below that and the shop is drawing down on reserves.
For seasonal businesses — especially in northern markets where winter weather affects driving behavior and repair patterns — knowing the breakeven job count lets you make staffing decisions in advance. Reducing to one technician instead of two below the breakeven job count preserves cash. Knowing the breakeven number before winter hits rather than discovering it in February is the difference between a managed slowdown and an unpleasant surprise. Most owners run this before a hire or a lease — it's a 60-second gut check worth running before your next big decision.
How to use it
- Enter Jobs Per Week — use a realistic monthly average, accounting for slow periods, not just your best stretch.
- Set Avg Labor Per Job from your actual average invoice labor portion and Avg Parts Per Job from your average cost-of-parts per repair.
- Adjust Parts Markup (%) to your standard markup on parts sold to customers.
- Enter Monthly Rent, Employee Wages ($/mo), and Monthly Overhead from your actual books.
- Read Gross Revenue, Parts Margin, Net Profit, and Per Job Profit — then use the jobs-per-week slider to locate your breakeven point.
Who it's for
- Two-tech shop evaluating whether to add a third bay — Models adding 8 more jobs/week against $1,200 in new overhead for the third bay, sees net profit increase of $2,900/month — confirming the expansion makes sense if the job volume materializes.
- Owner-operator considering a labor rate increase from $95 to $110/hour — Raises average labor per job from $200 to $231 and checks the net profit impact: $4,800/month additional revenue on the same job count, making the rate adjustment the easiest growth lever available.
- Shop owner reviewing parts markup after supplier renegotiation — Reduces parts cost per job from $180 to $155 after a better supplier deal, runs the calculator to see the $460/month margin improvement that results from the lower cost base at the same markup rate.
- Investor evaluating acquisition of an independent shop — Enters the target shop's job volume, labor, and overhead to compute normalized net profit independently of the owner's reported figures — uses the per-job profit output to identify whether current pricing supports the asking multiple.
Key terms
- Parts markup percentage
- The percentage added to the dealer cost of parts before billing the customer. A 45% markup on a $100 part produces a $145 customer charge and $45 in gross parts margin.
- Billable jobs
- Completed repair and maintenance orders that generate customer invoices. The primary volume metric driving gross revenue in a time-and-materials shop model.
- Gross parts margin
- The total dollar contribution from parts markup across all jobs in a period. Calculated as (markup rate divided by total markup rate plus one) times total parts revenue — or simply the markup dollars on all parts sold.
Frequently asked questions
Should I include sublet work in the jobs per week count?
If you send work to a specialty shop and bill the customer through your business, include it at the revenue you collect minus what you pay the sublet shop. The net margin on sublet is typically lower than in-house work, so it's worth tracking separately if it's a significant portion of your volume.
What is a typical parts markup percentage for an independent shop?
Independent shops commonly run 40-55% markup on hard parts and 25-40% on fluids and consumables. Specialty parts for older or rare vehicles can carry higher markup. The right number balances what your local market tolerates with what your supplier cost structure requires to maintain margin.
How should I handle fleet accounts in this model?
Fleet accounts typically get volume discounts on both labor and parts — if fleet work represents 30%+ of your volume, use a blended average across fleet and retail rates for your labor and parts inputs. Or run the calculator separately for fleet versus retail work to see their respective margins side by side.
What net profit margin is healthy for an auto repair shop?
Well-run independent shops typically achieve 12-22% net margin after a real owner salary is included. Below 10% usually means labor cost or parts pricing needs attention. Above 25% in a mature operation often indicates the owner is not drawing a market-rate wage, which flatters the margin.