Let's Move a Three-Bedroom House from Phoenix to Portland
A moving truck fuel cost calculatorearns its keep in the ten seconds it takes to prove the counter's MPG figure wrong. You've reserved a 26-foot truck for the 1,330-mile run up to Portland, the reservation sheet says the truck gets 10 miles per gallon, and the arithmetic looks easy: 133 gallons, about $440 in gas. Budget set. Except that's not what you'll spend.
The 10 mpg on that sheet describes an emptytruck. Yours won't be empty. A 26-footer weighs roughly 12,000 lb with nothing in it and is rated to carry up to 26,000 lb, so a load that fills it to the roof more than doubles the mass the engine has to push. Real MPG lands near 7.5. That's 177 gallons for the loaded leg, another two or three collecting and dropping off the truck, and $584 at $3.25 a gallon. The sheet was $144 light before you turned a wheel.
Here's how that $584 actually gets spent on the road. You'll stop for fuel four times, because 51 usable gallons at 7.5 mpg gives you about 385 miles of range and the trip is 1,330. That works out to roughly 43 cents a mile — a number worth holding onto, because it makes every detour and every wrong exit instantly priceable. And if you're dragging your car up there too, add it now: a tow dolly costs about $50 more in fuel over this route, a full car carrier about $102, because the carrier lifts all four wheels, adds around 2,200 lb, and puts a second flat face into the airstream.
One more lever before you leave. A box truck is a brick, so aerodynamic drag eats a bigger share of its fuel than it does in a car, and speed is the input you fully control. Holding 62 mph instead of 70 across this haul is worth roughly $70 — the Department of Energy's driving-efficiency data puts the penalty for every 5 mph above 50 at the equivalent of paying substantially more per gallon, and that curve is steeper for a shape like this.
So Why Does the Counter Say 10 MPG?
Because it's true, for a truck with nothing in it. Rental fleets publish one MPG number per truck size and it's measured the only way a fleet can measure it consistently: unloaded. Nobody is lying to you. They just aren't answering the question you're asking, which is what the truck burns with your dining table in it.
The gap scales with how full you pack. A quarter-loaded truck gives up about 6% of its rated MPG, half-loaded around 14%, and packed to the roof roughly 25%. That last figure is where most real moves land, and it's why owner reports for a loaded 26-footer cluster at 6 to 8 mpg against a claimed 10. The calculator above applies that penalty for you — pick the load level honestly rather than optimistically, because "packed to the roof" is what a three-bedroom house does to a truck.
Weight is also the constraint people discover too late. Every rental truck has a payload rating, and a full load of books, tools, or a garage's worth of gear will hit it before the box looks full. If you're close to the line, run the numbers through our truck payload capacity calculator first — an overloaded truck doesn't just burn more, it brakes worse.
Moving Truck MPG by Size — and the Surprise in the Middle
Here's every common rental size against the same 1,330-mile move, packed full, with gas at $3.25 and diesel at $3.75. Read the middle of this table twice, because it contradicts the advice everyone gives.
| Truck | Fits | Rated MPG | Loaded MPG | Tank | Fuel Cost |
|---|---|---|---|---|---|
| Cargo van | Studio / dorm | 18 | 13.5 | 25 gal | $325 |
| 10-12 ft truck | 1 bedroom | 12 | 9.0 | 31-33 gal | $487 |
| 15 ft truck | 1-2 bedroom | 10 | 7.5 | 40 gal | $584 |
| 20 ft truck | 3 bedroom | 10 | 7.5 | 40 gal | $584 |
| 26 ft truck, gas | 4+ bedroom | 10 | 7.5 | 57 gal | $584 |
| 26 ft truck, diesel | 4+ bedroom | 11 | 8.3 | 50 gal | $613 |
Rated MPG is the rental fleets' own unloaded estimate. Loaded MPG applies the 25% full-load penalty. Costs cover 1,330 loaded miles plus 25 empty miles for pickup and drop-off.
The 15-footer, the 20-footer and the 26-footer cost exactly the same to fuel. All three are rated at 10 mpg by the fleets, so "rent smaller to save on gas" buys you nothing across that entire range. The savings only appear when you drop two whole classes into a 12-footer or a van. If your stuff needs a 20 and you talk yourself into a 15 to save fuel, you've saved zero dollars and gained a packing problem.
The diesel row is the second surprise. It genuinely gets better mileage — 8.3 loaded against 7.5 — and it still costs $29 more, because a 10% mileage advantage doesn't cover a 15% price premium. The break-even is precise and easy to check at the pump: diesel wins only when it's priced within about 33 cents of regular, or roughly 10% above. Wider than that and the gas truck is cheaper. Check the current spread on the EIA's weekly fuel price series before you take the fuel type as a given.
The Trip Nobody Budgets: Driving It Back Empty
Everything above assumes a one-way rental — you drop the truck off in Portland and walk away. A local move works completely differently, and the difference is where most fuel budgets fall apart.
A local rental has to come home. Say your new place is 18 miles away and your stuff needs two loads in a 15-footer. You drive 18 miles loaded, 18 back empty, 18 loaded again, 18 back empty, plus about 25 miles collecting and returning the truck. That's 97 miles driven for an 18-mile move, and 61 of them are with an empty box. At 7.5 mpg loaded and 10 mpg empty, the fuel comes to $35 — and 56% of it is spent moving nothing but air.
Now do the same move in one load with a 26-footer. Eighteen miles loaded, 43 empty, 61 miles total, $22 in fuel. And here's the part that dwarfs both figures: local rentals bill a per-mile charge on top of the day rate, commonly around 99 cents. Those 97 miles cost $96 in mileage; the 61 miles cost $60.
| 18-mile local move | Miles driven | Fuel | Mileage @ $0.99 | Total |
|---|---|---|---|---|
| Two loads, 15 ft truck | 97 | $35 | $96 | $131 |
| One load, 26 ft truck | 61 | $22 | $60 | $82 |
The bigger truck wins by $49, and it wins on the exact axis people expect it to lose. Its day rate typically runs $10 to $15 above the 15-footer, so you're still $35 or so ahead. On a local move, the number that matters is how many times you cross town, not how big the box is. One trip in a truck that's too big beats two trips in one that fits.
Three Charges People Read as One
The fuel estimate above is one line on a contract that has several, and conflating them is how a $584 fuel budget turns into a $900 surprise.
Fuel is yours to buy. You collect the truck at some fuel level and you return it at that same level. Nothing about the day rate or the mileage charge covers a single gallon.
Mileage is billed separately, and only on local rentals. One-way contracts include a fixed mileage allowance sized to your route, so the per-mile field in the calculator should stay at zero for those. Local contracts meter every mile — including the empty ones — which is why the 97-mile version of an 18-mile move costs what it does.
Returning it low is the expensive mistake.Hand back a 26-footer a quarter tank light and the refuelling service bills around $9.50 a gallon. That's 14 gallons at about $135, against $46 if you'd stopped at a station — a $90 premium, and most contracts stack a service fee on top of it. The last fill-up before drop-off is the highest-return ten minutes of the whole move.
Two smaller notes worth planning around. If you're following the truck in your own car rather than towing it, that car has its own fuel bill — price the same route in the trip gas calculator and add it, because two drivers usually beats a car carrier on fuel and always beats it on parking. And if you are towing, our towing fuel cost calculator breaks the trailer penalty down by weight and frontal area if you want a tighter number than the flat percentages used here. For a multi-day haul with hotels and meals stacked on top, the road trip cost calculator will give you the whole picture rather than just the pump.