Gas is often the single biggest variable expense on an RV trip. The exact cost will depend on your rig’s fuel efficiency, how far you’re going, and where you’re filling up. But you can still get a solid estimate before you leave the driveway. Here are the formulas and information you need to calculate your fuel cost for your next trip.
RV Gas Costs At A Glance
| RV Type | Avg. MPG | Typical Tank Size | Cost Per Fill-Up (at $4.50/gal) | Range Per Tank |
| Class A Motorhome | 6–8 MPG | 70–150 gallons | $315–$675 | 420–1,200 miles |
| Class C Motorhome | 10–13 MPG | 25–55 gallons | $113–$248 | 250–715 miles |
| Class B Campervan | 15–18 MPG | ~25 gallons | ~$113 | 375–450 miles |
| Travel Trailer | 12–16 MPG* | 15–30 gallons* | $68–$135* | 180–480 miles* |
*Fuel efficiency and tank size for travel trailers reflect the tow vehicle, not the trailer itself.
Why Gas Costs Vary So Much for RV Trips
Gas prices in 2026 are running significantly higher than in prior years. The national average as of May 7, 2026 is $4.52 per gallon — up about 23% compared to the same period in 2025. California has the most expensive gas at $5.84 per gallon, while Oklahoma offers the lowest average at $3.38. If you’re planning a cross-country trip, your fuel costs will shift considerably depending on the states you pass through.
Beyond price at the pump, several other variables affect your real-world RV fuel costs:
- RV type and size: A Class A diesel pusher burns fuel at a completely different rate than a Class B campervan.
- Load weight: The heavier your rig — food, water, gear, passengers — the harder the engine works and the worse the mileage.
- Terrain: Mountain passes and steep grades can significantly impact your fuel economy.
- Speed: Fuel efficiency drops sharply when you go past 60–65 MPH for most RVs.
- Wind and weather: Headwinds can add serious resistance to a large, boxy vehicle.
How to Calculate Your RV Gas Costs
Use these formulas to estimate your total fuel cost before any trip:
| Calculation | Formula | Example (Class C at $4.50/gal) |
|---|---|---|
| Miles per full tank | MPG × Tank size | 10 MPG × 40 gal = 400 miles |
| Cost to fill up | Tank size × Price per gallon | 40 gal × $4.50 = $180 |
| Tanks needed for trip | Miles to destination ÷ Miles per tank | 1,050 ÷ 400 = 2.63 tanks |
| Total fuel cost | Tanks needed × Fill-up cost | 2.63 × $180 = $473 |
Plug in your own MPG, tank size, current local gas price, and trip distance to get a personalized estimate. GasBuddy is a useful free tool for checking current prices along your route before you leave.
RV Gas Mileage by Class
Here’s what you can expect for gas mileage, depending on which class of RV you’re driving.
Class A Motorhomes
Class A motorhomes are the heaviest rigs on the road. Between premium appliances, slide-out mechanisms, and a substantial powertrain, these coaches put real demand on their engines. On average, expect 6–8 MPG under normal highway conditions, and as low as 4 MPG on steep or hilly terrain. Class A tanks are sized accordingly — ranging from about 70 gallons on smaller Class As to over 100 gallons on large coaches, with some diesel pushers capable of holding up to 150 gallons.
At current prices, filling a 100-gallon Class A tank from empty costs approximately $450 at the national average.
Class C Motorhomes
Class C motorhomes are the sweet spot for families — they have more room than a van, and they’re more fuel-efficient than a Class A. These motorhomes get substantially better mileage than Class As, averaging 10–13 MPG under normal conditions. Tank sizes typically run from 25 to 55 gallons, though this varies by manufacturer and model length.
A mid-size Class C with a 40-gallon tank costs roughly $180 to fill at current national average prices.
Class B Campervans
Class B campervans offer the best fuel economy of any drivable RV category. These vans typically get 15–18 MPG — not far off a full-size truck. Most carry around 25 gallons of fuel, putting a fill-up at approximately $113 at current prices.
Travel Trailers and Fifth Wheels
Travel trailers don’t carry their own fuel — we’re calculating the fuel used for the tow vehicle. Fuel economy when towing varies widely based on trailer size, tow vehicle capability, and aerodynamics. A small travel trailer behind a half-ton truck might yield around 12 MPG; heavier fifth wheels behind a one-ton often drop to 9–11 MPG. Some owners report 15–16 MPG with lightweight trailers and efficient tow vehicles.
Most full-size pickup trucks carry between 15 and 30 gallons of fuel. Know your tow vehicle’s tank size and check your real-world towing economy before you start estimating costs.
Diesel vs. Gas: Which Is More Fuel Efficient?
Diesel consistently wins on efficiency. According to the U.S. Department of Energy, diesel fuel contains roughly 10–15% more energy than gasoline, meaning diesel vehicles can often travel 20–35% farther on a gallon of fuel than their gasoline counterparts. That’s why most Class A motorhomes at the higher end of the market are diesel pushers — the rear-mounted engine also improves weight distribution and ride quality.
The tradeoff is that diesel is often more expensive per gallon than regular unleaded and is less widely available than gasoline in rural areas. As of early April 2026, diesel prices averaged $5.43 nationally — more than $1 per gallon above regular gasoline in many markets. For buyers deciding between gas and diesel, diesel is definitely more efficient, but the current price and availability are worth factoring into your total cost of owning a diesel vehicle.
How Gross Vehicle Weight Affects Fuel Economy
Every RV has a Gross Vehicle Weight Rating (GVWR) — the maximum safe loaded weight. Heavier vehicles burn more fuel, and the gap between your empty weight and your GVWR is filled by everything you bring: water, food, clothes, gear, passengers, and pets.
One of the easiest ways to improve your RV’s fuel economy is to reduce load weight. Traveling with empty or nearly empty fresh-water tanks and buying groceries at your destination rather than hauling a full pantry can meaningfully improve your MPG on a long trip.
Tips for Reducing RV Fuel Costs
- Use GasBuddy: Before filling up, check GasBuddy for the lowest prices within a reasonable detour. On a 100-gallon fill, even $0.10/gallon savings adds up to $10 per tank.
- Keep your speed at 60–65 MPH: Fuel economy for most RVs drops sharply above this range due to aerodynamic drag.
- Lighten the load: Travel with less water and food on board; shop at your destination.
- Plan your route around fuel prices: If you’re driving through California, fill up before crossing the state line — average prices there are currently among the highest in the country.
- Consider diesel if you’re buying an RV: The efficiency advantage is real on long trips, even with the current price premium.
- Maintain your rig: Properly inflated tires, clean air filters, and a well-tuned engine all improve fuel efficiency.
Is RVing Environmentally Friendly?
RVs aren’t the most fuel-efficient way to travel, it’s true. But comparing an RV trip to the full environmental cost of a conventional vacation changes things. Flying generates a big carbon footprint per passenger, and hotel stays involve energy consumption, supply chains, and daily housekeeping that add up. An RV trip consolidates lodging and transportation, and if you’re camping rather than staying in hotels, the total footprint is often fairly close.
That said, choosing a smaller rig when possible, traveling at efficient speeds, and reducing unnecessary fuel consumption are all straightforward ways to minimize your impact.
Key Takeaways
- Gas is a major expense in RV trips, with costs varying based on fuel efficiency, distance, and state gas prices.
- Class A motorhomes get 6-8 MPG, while Class B campervans achieve 15-18 MPG, showing significant differences in rv gas mileage.
- Several factors affect your RV’s fuel costs, including load weight, terrain, and driving speed.
- Using formulas, you can estimate RV gas costs based on MPG, tank size, and trip distance.
- Tools like GasBuddy can help you find the best fuel prices and save money on your trip.
Frequently Asked Questions About RV Gas Mileage
The cost in gas to drive an RV depends on your RV class, trip distance, and current gas prices. As a rough benchmark at current national average prices (~$4.50/gallon): a Class A motorhome costs $315–$675 per fill-up; a Class C costs $113–$248; and a Class B van costs around $113. Use the formulas in this article to calculate your specific trip cost.
Class B campervans get the best fuel economy of any RV, averaging 15–18 MPG. Among towable rigs, lightweight travel trailers towed by efficient half-ton trucks can approach 15–16 MPG. In general, smaller and lighter means better fuel economy across every category.
If you travel far, usually diesel is worth it. Diesel’s 20–35% efficiency over gasoline means fewer fill-ups over a long trip. The current national diesel premium (~$1/gallon above regular gasoline) partially offsets those savings, so the math depends on how much you drive. Diesel pushers also tend to have better torque and ride quality than gas-powered Class As.
GasBuddy is the most widely used free tool for finding the lowest prices along your route. You can plan to fill up strategically by avoiding high-price states like California when possible, and filling up in lower-cost markets, which can save meaningful money on long trips.
Yes, towing an RV can significantly hurt the economy. Towing adds aerodynamic drag and weight, which reduces your tow vehicle’s MPG considerably. A truck that normally gets 20 MPG might drop to 10–13 MPG when towing a travel trailer. Always use your towing MPG — not your unladen MPG — when estimating fuel costs.
Planning an RV trip and want to try before you buy? Browse RV rentals on RVshare and find the right rig for your budget — from fuel-efficient Class B vans to full-size Class A motorhomes.
