Turn your weekly job volume and average job value into a monthly profit picture — materials cost, labor, truck expenses, and overhead all factored in.
Twelve jobs a week at a $480 average sounds like a six-figure shop — and it is, on the top line. But the diesel, the journeyman's wages, the materials that crept from 28% to 34% when your supplier quietly repriced PVC, and the truck that needs brakes all come out before you see a dime. This calculator runs jobs per week times average job value, then subtracts the real cost of doing the work, and hands you a monthly net you can read in under two minutes.
The model handles both solo owner-operators and multi-technician shops. Enter your jobs at the business level, load your actual cost percentages and fixed expenses, and read the result. Change one variable — say, raise average job value by $75 — and see exactly what that does to the bottom line before you update your service pricing.
How job volume translates into monthly gross revenue
Monthly gross is Jobs Per Week times Working Weeks Per Month times Average Job Value. A two-technician shop running 12 jobs per week at $480 average job value on a 4.3-week month generates roughly $24,768 in monthly gross. The calculator uses 4.3 as the default working-week multiplier, which reflects the actual average across a full year — slightly more accurate than a flat 4.
Average job value is the input with the most upside per unit of effort. Plumbing jobs range from $150 emergency service calls to $8,000 repiping projects, and the mix matters more than raw volume. A shop doing 8 jobs per week at $650 average outperforms one doing 14 jobs at $350 average, net of proportionally higher labor and vehicle costs. Track your actual average from invoices, not a target rate.
Working Weeks Per Month handles the fact that plumbing demand is seasonal and not every week runs full. A shop that takes two weeks in December at reduced capacity should enter a realistic annual average rather than peak-season numbers. The net profit figure is only as useful as the accuracy of the volume inputs.
Materials cost: the variable that swings with every job
Materials and Parts Cost (%) is applied as a percentage of gross revenue to produce a dollar figure for parts and supplies consumed in the field. For a general plumbing shop, materials typically run 25–40% of job revenue depending on the mix of service calls versus installation work. Pure service and diagnostic calls have low materials cost — parts might be a $45 flapper and a wax ring. Full bathroom rough-in or water heater installation can push materials to 35–40% of the job value.
Set this percentage to your actual average across all job types, pulled from your job costing records or a review of last quarter's invoices. If you do not currently job-cost, a field-by-field estimate — what did materials cost on your last 20 jobs as a percentage of each job price? — gets you close. Understating materials cost is the most common error in plumbing revenue models, and it inflates net profit by several thousand dollars a month on an active shop.
Price increases from suppliers often hit without warning. A 5-point increase in materials cost percentage on a $25,000 monthly gross is $1,250 in lost margin. If you have not reviewed your parts pricing and job pricing alignment in the last six months, run the calculator with your old materials percentage and then bump it by 5 points — the difference is the exposure you are carrying.
Labor, vehicles, and the fixed cost floor
Monthly Labor Cost should include wages for all technicians plus any office or dispatch staff. For a shop with one journeyman at $5,200 a month and a part-time dispatcher at $1,400, total labor is $6,600 before the owner's draw. This number does not flex with job volume — a slow week still costs $6,600. It is the fixed floor that gross revenue must clear before anything else gets paid.
Monthly Vehicle and Fuel costs are often underestimated because they are paid incrementally — a tank of diesel here, a tire rotation there. Add up your truck payments or depreciation, fuel, oil changes, and maintenance for all vehicles in service. A two-truck shop often runs $1,800–$3,200 a month in vehicle costs. That number belongs in the model because it is real cash out the door.
Monthly Overhead rounds out the fixed cost structure: liability insurance, tools and equipment, software for scheduling and invoicing, and professional licenses. For most plumbing shops, overhead excluding labor and vehicles runs $1,000–$2,500 a month. Monthly Marketing, if you run Google Local Services Ads, a website, or direct mail, is entered separately and belongs in the model too — it is a deliberate cost of growth.
What net margin to target in plumbing
A healthy plumbing business should target 15–25% net margin after all costs including the owner's full market wage. Above 25% and the business is either underloaded on growth investment or the owner is not paying themselves properly. Below 10% and the model is fragile — one slow month or an unexpected truck repair wipes out the cushion.
Residential service plumbing tends to generate higher margins per dollar of revenue than large commercial projects because billing rates are less compressed by competitive bidding. A shop that does 70% residential service calls and 30% new construction installation typically runs better margins than one doing the inverse, even at lower gross revenue. The calculator lets you see this by adjusting average job value and materials cost percentage to reflect different job mixes.
Pricing a rate increase before you announce it
Raise Average Job Value by $50 in the calculator. On 12 jobs per week over 4.3 weeks, that is $2,580 in additional monthly gross at almost no incremental cost — materials and labor do not increase because the work is the same. The full $2,580 minus the materials cost percentage flows to net profit. On a 30% materials cost assumption, you keep roughly $1,800 in additional net per month from a $50 price adjustment.
If you have not raised rates since materials and labor costs went up, the calculator shows the exact margin gap you have been absorbing — in dollars per month, not percentages. Run the numbers before you commit new prices to the service menu. Start a free trial to save the model and revisit it each time your supplier sends a price notice.
How to use it
- Enter Jobs Per Week and Working Weeks Per Month based on your actual schedule, not peak capacity.
- Set Average Job Value to the mean revenue across all job types using your last quarter of invoices.
- Enter Materials and Parts Cost (%) to reflect your real blended parts-to-revenue ratio.
- Fill in Monthly Labor Cost, Monthly Vehicle and Fuel, and Monthly Overhead as flat dollar figures.
- Add Monthly Marketing if applicable, then read net profit and margin — adjust one input at a time to test pricing or cost changes.
Who it's for
- Solo plumber evaluating whether to hire a technician — Increases jobs per week by 6 and adds $5,500 in monthly labor cost, then checks whether the added gross revenue outpaces the new overhead.
- Shop owner reviewing after a materials cost increase — Raises materials percentage from 28% to 34% to reflect supplier price increases and sees how many additional jobs are needed to hold the same net profit.
- Plumbing business setting service call pricing — Tests raising average job value from $420 to $480 to see the net profit gain before updating the service price menu.
- Two-truck shop modeling a fleet expansion — Adds a third truck to Monthly Vehicle cost and increases jobs per week proportionally to check whether the incremental gross revenue justifies the vehicle expense.
- Owner preparing a bank loan application — Uses the monthly net profit output as part of a cash flow projection, adjusting inputs to show conservative, mid-range, and optimistic scenarios.
Key terms
- Average job value
- The mean revenue earned across all completed plumbing jobs in a given period, used as the primary revenue-per-unit input.
- Materials cost percentage
- Parts, supplies, and materials used in the field expressed as a percentage of job revenue — the primary variable cost in a plumbing business.
- Net margin
- Net profit as a percentage of gross revenue after all costs including labor, vehicle, overhead, and marketing.
- Working weeks per month
- The average number of productive billing weeks in a month; typically 4.3 on an annual basis, adjusted for seasonal or operational variation.
Frequently asked questions
What average job value should I enter if my jobs vary widely?
Use the arithmetic mean from your last 3 months of closed invoices. If your job range is $180 to $4,000, a simple average will include both extremes proportionally. If you want to model a specific job mix change — say, adding more water heater replacements — adjust the average ticket to reflect that shift.
Should I include my own pay in Monthly Labor Cost?
Yes, always. An owner-operator who leaves their own wage out of labor makes the business look more profitable than it is. Load at least the wage you would pay a licensed journeyman plumber to do your work — that is your real cost of production.
How do I account for unbillable time in the model?
Unbillable time — quoting, driving to jobs that do not close, warranty callbacks — reduces your effective jobs per week. If you book 15 jobs but 2 per week are unbillable service or callback hours, enter 13 as your effective billed jobs per week. The model outputs are only as accurate as the billed job count.
What materials cost percentage is typical for plumbing?
Service calls with small parts typically run 15–25% materials. Fixture installation runs 30–40%. Full rough-in or repiping work can approach 40–50% depending on pipe and fixture specification. A blended rate of 28–35% is common for a residential service shop with a mix of call types.
Does this model work for a commercial plumbing contractor?
Yes, with one adjustment: commercial projects have longer payment cycles. The revenue model holds, but you may want to run it conservatively on working weeks and average job value to account for payment delays on commercial invoices that stretch 30–60 days.