Calculating Your Fuel Cost for an RV Road Trip

Planning a road trip? Whether you’re crossing the country in a diesel-pusher motorhome, towing a fifth wheel across state lines, or simply heading out for the weekend in a camper van, one thing is certain: Fuel will be one of your biggest travel expenses. And with gas and diesel prices fluctuating regularly, calculating your fuel cost for an RV road tip ahead of time can help you budget better — and avoid budgetary surprises mid-trip.

So, before you hit the road, let’s break down how to estimate fuel costs accurately, what factors affect fuel economy, and how to plan efficiently.

 

Why Fuel Cost Planning Matters

Point blank, fuel is one of the top three recurring expenses for RV travelers. (The other two are camping fees and food.) While some travelers use rough ballpark estimates, taking a little time to run the numbers can make a big difference in how you plan your route, stops, and even your travel pace.

This is especially true if:

• You’re towing a heavy trailer or fifth wheel;
• You drive a Class A or diesel pusher with lower miles per gallon (MPG);
• You’re planning a long-distance trip with limited fuel stations; or
• You’re on a tighter travel budget.

The good news? Once you understand a few simple metrics, calculating fuel costs becomes quick and easy.

 

The Formula to Estimate Fuel Costs

Here’s the basic equation:

(Total Trip Miles ÷ Miles Per Gallon) × Cost Per Gallon = Estimated Fuel Cost

Now, let’s turn it into a real-world example from a trip my wife and I are about to take. We’re heading on a weeklong adventure through one of our absolute favorite regions — the Eastern Sierras. We’ll be hitting Mammoth Lakes, Yosemite, and Lake Tahoe, and we’re bringing one of our best friends along for the ride. That means a bit more human weight (very minimal extra weight … so they don’t kill me … lol), a few more miles, and a lot more fun.

Here’s what I calculated:

• Distance (with day trips): 1,200 miles round-trip
• Rig: Diesel Class C towing a Jeep Grand Cherokee
• Adjusted MPG (mountain terrain + towing): Roughly 9 MPG
• Diesel cost in California: Approximately $5.25/gallon

(1,200 ÷ 9) × 5.25 = ~$700

Yep, it’s a little higher than average — but completely worth it for the experience, the scenery, and the memories. By accounting for terrain, weight, and how we’ll switch to the Jeep for local exploring, the estimate is much closer to what we’ll actually spend. I intentionally left the fuel cost a little higher on the average, so that I would feel comfortable knowing that estimate is likely on the higher end. (I prefer to be a little off and save than be a little off and go over budget.)

 

Step-by-Step: Calculating Fuel Cost for a Trip

1. Know your miles per gallon.

This is the most important variable. Here’s a general range to give you a rough idea:

• Class A gas motorhomes get around 6–10 MPG
• Class A diesel motorhomes average 7–12 MPG
• Class B vans can get 14–20+ MPG
• Class C RVs typically get 9–13 MPG
• Towing a fifth wheel or travel trailer usually yields 8–12 MPG, depending on your tow vehicle

Not sure what your MPG is? Use your trip computer if equipped, or manually track miles and fuel during a test trip. You’ll quickly get a good average.

 

2. Know the distance of your trip.

I use Google Maps, but other options like RV Trip Wizard, or a similar route planning tool to calculate your total mileage, works. Be sure to factor in any detours, scenic byways, or side-trips.

Pro Tip: Add 10–15 percent cushion for spontaneous detours or scenic stops. That’s what I did, and by leaving the price per gallon at the higher diesel cost instead of adjusting for lower gas prices in the Jeep, I know that I should be more than good on my budget.

 

3. Use current fuel prices.

Gas and diesel prices vary widely by region, and diesel is often more expensive — especially in places like California. A simple Google search for the specific region can work, but you can also use one of the following apps or sites to check real-time fuel costs along your route:

• GasBuddy
• Gas Guru
• Pilot Flying J or Love’s apps
• RV LIFE Trip Wizard (includes fuel cost estimator)

 

Factors that Affect Fuel Economy

Even if your rig averages 10 miles per gallon, that number can shift depending on conditions. Consider these variables:

• Speed: Driving 70 mph vs. 60 mph can reduce fuel efficiency significantly — especially when towing.
• Wind and Elevation: Strong headwinds or steep climbs = lower MPG.
• Tire Pressure: Underinflated tires can reduce fuel economy and lead to blowouts.
• Weight: The more gear or passengers you’re carrying, the harder your engine works.
• Driving Style: Gentle acceleration and cruise control help improve efficiency.

 

Gas vs. Diesel: What’s the Difference?

There’s a common myth that diesel always saves you money. The truth is more nuanced. Here’s how they compare:

• Fuel Cost: Gas is usually cheaper per gallon, while diesel can cost significantly more — especially on the West Coast.
• Miles Per Gallon: Diesel rigs generally go farther on a gallon, averaging 8–12 MPG vs. 6–10 MPG in gas rigs.
• Maintenance: Diesel engines tend to require more expensive service, but at longer intervals.
• Power and Torque: Diesel engines have better low-end torque, which makes them ideal for towing and climbing hills.

So, while diesel may seem like a better deal for long hauls, the higher price per gallon and maintenance costs often balance things out over time.

 

Quick Tools to Help You Estimate Fuel Costs

Instead of doing math manually every time, try one of these:

• RV LIFE Fuel Cost Calculator: Integrated with trip planning
• GasBuddy Trip Cost Estimator: Free and easy to use
• Roadtrippers Plus: Great for mapping and cost planning in one tool
• Fuelly (App): Tracks your actual MPG and cost data over time

 

Budgeting Tips to Save on Fuel

So, you’re done calculating fuel cost for your trip, but still want to stretch your fuel dollars a bit further? Try these tips.

• Drive slower: Reducing your speed from 70 to 60 mph can boost MPG significantly.
• Travel during off-peak hours: Avoid traffic and idle time.
• Stay longer per stop: Fewer drive days = fewer fill-ups.
• Use membership cards or apps: Memberships like Pilot Flying J’s RV Plus Card or Good Sam fuel discounts can save you per gallon, while apps like Upside can get you cash back at certain pumps.
• Travel lighter: Ditch excess gear or empty your tanks before travel days if possible.

 

Sample Fuel Budget by RV Type

Here’s a rough idea of what it might cost to drive 1,000 miles at an average fuel cost of $4.00 per gallon:

• A Class A gas motorhome averaging 7 MPG would cost around $571
• A Class A diesel rig getting 10 MPG would cost about $400
• A Class B van with 17 MPG would come in closer to $235
• A truck towing a fifth wheel at 9 MPG would cost approximately $444
• A truck towing a travel trailer and averaging 11 MPG would be about $364

These are ballpark estimates, but they help you plan with realistic numbers when calculating the fuel cost for your trip.

 

Don’t Let Fuel Costs Surprise You

Calculating fuel costs isn’t about scaring yourself out of traveling—it’s about being informed so you can budget better and make the most of every gallon.

Planning ahead gives you flexibility. Want to take a longer route with more scenic stops? Go for it. Prefer to boondock and save campground fees? That might help offset the fuel cost.

Either way, knowing what to expect at the pump means fewer surprises—and more peace of mind while you enjoy the ride.

And at the end of the day, every mile brings you somewhere new. So, grab your map, run your numbers, and get back to planning the fun stuff.