Fixed vs Variable Costs for Owner-Operators: The Full Breakdown

By Erkan Ozturk — owner-operator, HAWD Trucking LLC (USDOT 4436030), Chattanooga TN · Last updated July 11, 2026

What are fixed costs for a semi truck?

Fixed costs are the bills that arrive whether the truck moved or sat. The truck payment doesn’t know you spent three days waiting on a reload. Insurance doesn’t care that diesel spiked or that the board went quiet. The ELD subscription, the parking spot, the phone plan, the accountant — they all bill by the calendar, not by the odometer.

That calendar-billing is exactly what makes fixed costs dangerous in a slow week. Every one of those dollars still has to come out of the miles you actually ran, so the fewer miles you run, the more each mile has to carry. A truck payment never gets bigger — but on a 1,500-mile week it gets a lot heavier per mile.

What are variable costs in trucking?

Variable costs are the ones the odometer creates. Every mile burns fuel, wears tires, uses up the engine’s life, and moves you closer to the next PM service. Park the truck and these costs stop; run 3,000 miles and they run right alongside you. Fuel is usually the largest of them, and it prices cleanly per mile: diesel price divided by MPG. At the EIA weekly U.S. on-highway average of $4.578 per gallon (published July 6, 2026) and 7.5 MPG, fuel alone is about $0.61 per mile — the full mechanics live in how do I calculate fuel cost per mile for a truck?

Maintenance and tires behave the same way, just on a slower clock: you don’t pay them every mile, but every mile earns a slice of the next bill. The honest way to carry them is as a per-mile reserve — money set aside now for a repair that hasn’t happened yet. Tolls are variable too, but they belong to specific loads rather than to your base cost per mile, so they get counted per trip.

Which owner-operator expenses are fixed and which are variable?

Here is the full stack — every recurring cost of running one truck, sorted by how it bills and where it lands in your cost per mile. Print it, and check your own bank statement against it line by line.

Two nuances worth naming. First, a truck lease charged per mile instead of per month belongs on the variable side — it scales with the odometer, so it rides in variable CPM, not fixed. Second, the tax-and-permit stack is genuinely mixed: IRP, UCR, and HVUT are flat annual bills, while IFTA settles on fuel burned and the New York, Kentucky, New Mexico, and Oregon weight-distance taxes charge by the mile — which is why the cleanest bookkeeping move is to spread the whole stack across your miles as one per-mile tax line.

LoadWizz’s wizard covers this full owner-op cost stack, item by item, when it builds your base CPM.

Why does the fixed vs variable split matter?

Because only one side of the ledger responds to how much you drive. Variable cost per mile is roughly the same whether you run 1,500 or 3,000 miles this week. Fixed cost per mile is pure division — the same pile of bills spread over however many miles you actually ran — and division punishes small denominators:

fixedCPM = weeklyFixed ÷ weeklyMileGoal

Read that middle column slowly. Nothing about the truck changed between the rows — same payment, same insurance, same parking spot. The only thing that moved was the denominator, and it swung the total cost of a mile by 74 cents, from $1.85 to $2.59. A load paying $2.20 per mile clears the 3,000-mile truck by 35 cents and buries the 1,500-mile truck by 39. Same truck, same rate, opposite outcomes. That’s also why weekly mile goals deserve their own honest conversation — set the goal too optimistically and every fixed-CPM number under it is fiction.

For scale on what real trucks run: owner-operator tax and accounting firm ATBS reported its average client netted $71,800 on roughly 95,000 miles in its 2025 figures — about 1,800 miles a week averaged across all 52, including the slow ones. And ATRI’s “An Analysis of the Operational Costs of Trucking: 2025 Update” (July 2025, 2024 data) put the industry’s average total marginal cost at $2.260 per mile — a fleet figure that includes driver wages, useful as a landmark rather than a target. Your own split is the number that decides your week.

How do fixed and variable costs feed your cost per mile?

The split isn’t bookkeeping trivia — it is the exact architecture of your base cost per mile. Fixed costs get summed weekly and divided by your mile goal; variable costs arrive already priced per mile; fuel gets its own line because it moves weekly with the diesel market:

baseCPM = fixedCPM (weeklyFixed ÷ weeklyMileGoal) + variableCPM + fuelCPM (price ÷ MPG)

Building each of those three components with your real numbers is its own walkthrough: how do I calculate cost per mile for a semi truck? covers the full build. And base CPM is the numerator of the next number that matters — the floor rate that actually covers you once dispatch and factoring take their percentage of gross: how do I calculate my break-even rate per mile?

The order of operations is the whole game: sort every bill into fixed or variable, spread the fixed side over honest miles, price the variable side per mile, and only then look at a load board. More of the math — deadhead, tolls, dollars per estimated hour — lives in the Learn library.