Best Gas Can for an RV Generator: How Much Fuel to Carry and How to Store It

A portable generator is only as useful as the fuel you bring for it. Run out on day two of a dry-camping trip and you're packing up early or driving to town with empty cans. This guide works out how much gas an RV generator actually burns, how many cans that means for your trip, which can size is easiest to pour into a small generator tank, and how to carry and store the fuel safely.

The short answer

For most RVers running a 2,000–4,000 watt inverter generator, the best setup is one or two red steel 20L (5.3 gal) gas cans for the bulk of your fuel, plus a 10L (2.6 gal) can for easy top-ups, carried outside the living space in a proper holder. Our pick is the Wavian 20L Red with the Wavian 10L Red. They're welded steel, they seal tight, they come with a locking spout, and they're EPA and CARB compliant as supplied.

How much gas does an RV generator use?

Generator makers publish a tank size and a run time at a given load. Divide one by the other and you get a fuel rate you can plan with. Here are the numbers for popular Westinghouse models we carry:

These figures come from each maker's rated run time, so treat them as a floor. Rated run time is usually measured at light load, often 25%. Running the roof air conditioner pushes the load well past that. As a rough guide, plan on about double the 25% figure on hot days when the A/C runs. Watch your own generator's fuel gauge or tank level for a day or two and you'll have your real number.

How many cans should you bring?

Take your daily fuel use, multiply by the days you'll be away from a gas station, and add a margin of a day or so:

• Light use (lights, fans, charging, a few hours of microwave and coffee maker on a 2,000–2,500 W inverter): around 1 gallon a day. One 20L can covers a long weekend with room to spare.
• A/C in the afternoon (a 3,300–4,000 W inverter running a 13,500 BTU roof unit for several hours): plan on 2–4 gallons a day. Two 20L cans cover about 3–4 days.
• All-day A/C, or a larger open-frame generator: 4+ gallons a day. Consider a dual fuel generator on propane, or adding solar and lithium to cut generator hours.

Not sure what size generator your RV needs? See What Size Westinghouse Generator Do I Need? and Best Westinghouse Generator for Your RV.

20L or 10L: which can is best for a generator?

Small inverter generators have small tanks: 0.79 gal on the iGen1500c, 1.1 gal on the iGen2550c, 1.69 gal on the iGen4000DFc. Topping one up from a full 20L can means lifting about 40 lb and pouring into a small opening. That's doable, but it's where most spills happen.

• 20L (5.3 gal): the reserve. The most fuel per can and per mount. Keep it on the rack or in the truck bed and use it to refill the smaller can.
• 10L (2.6 gal): the pour can. Half the weight, easy to control. It refills an iGen2550c tank twice, or an iGen1500c tank about three times.

For larger tanks like the 3.4 gal iGen5000c or the 4.7 gal WGen5300sc, a 20L can makes sense for direct refills. One 20L can refills the iGen5000c about one and a half times. For a full size comparison, see Wavian jerry can sizes.

Why steel beats the plastic gas can

The red plastic can from the hardware store works in the garage. On an RV it rides outside in the sun for months, bounces down washboard roads, and gets opened at a campsite with people around. A welded steel can holds up better there:

• It seals. A locking closure and a gasket keep fumes in, which matters when the can rides near your door or your tow vehicle.
• It handles UV and heat. Coated steel doesn't fade, bulge or go brittle in the sun.
• It pours cleanly. The Wavian spout locks onto the can, so you get a steady pour into a small generator tank instead of the glug-and-splash of many safety spouts.
• It's compliant. Wavian cans are EPA and CARB compliant as supplied, so they're legal to buy and use in California.

For a deeper comparison, see Wavian vs Rotopax vs Scepter vs plastic utility jugs.

Gas or propane for your generator?

If your generator is dual fuel (the Westinghouse "DF" models), you can skip some gas cans altogether. Propane doesn't go stale and can come from your RV's tanks or a spare cylinder. The trade-off is roughly 10% less power. The iGen4000DFc, for example, makes 3,300 rated watts on gas and 2,970 on propane. It also runs up to 17 hours on propane at 25% load, versus 7 hours on its gas tank. Many RVers run propane day to day and keep one red gas can as a backup. See How to Run a Westinghouse Dual Fuel Generator on Propane and how much power a dual fuel generator loses on propane.

A motorhome with a built-in generator usually draws from the main fuel tank, and many are plumbed to stop drawing at about a quarter tank so you can still drive to fuel. A spare can is still useful there as a reserve for the drive itself.

Keeping generator gas fresh

Stale gas is the number-one reason a generator won't start after sitting. Ethanol-blended gasoline absorbs moisture and breaks down within a few months.

• Add fuel stabilizer when you fill a can you won't use soon.
• Write the fill date on the can.
• Use up stored gas within a few months. Pour leftover gas into your tow vehicle and refill with fresh gas before the next trip.
• Use ethanol-free gas for long-term storage if it's available near you.
• Before storing the generator, follow the maker's storage steps. See Westinghouse Generator Maintenance & Storage.

Where to carry gas cans on an RV

Keep fuel outside the living space, upright, and secured so it can't tip or slide. Good options:

• Tow vehicle bed or hitch carrier. The simplest spot for a travel trailer or fifth wheel.
• Trailer tongue or A-frame. A locking holder like the ARK jerry can holder keeps the can tight and deters theft at the campsite. Remember that a full can adds tongue weight.
• Rear bumper. Many RV bumpers aren't built to carry weight. Check yours before you hang a full can on it, and never block lights or the plate.

Avoid basement compartments that share air with the cabin, spots next to the generator exhaust, and anywhere near the furnace or water heater vents.

Refueling the generator

Always shut the generator off and let it cool before you refuel. Pour on level ground with the spout locked on, and stop before the tank is full. Wipe up any drips, and close both caps before you restart. The full step-by-step generator fueling routine, plus filling and storing, is in How to Use a NATO Jerry Can Safely.

Use red for gasoline and keep each can dedicated to one fuel. See Jerry Can Color Codes Explained.

FAQ

What is the best gas can for an RV generator?

A sealed steel can with a locking spout, in red for gasoline. A 20L (5.3 gal) can holds the bulk of your fuel, and a 10L (2.6 gal) can makes small generator tanks easy to top up. We recommend the Wavian NATO cans.

How long will a 5 gallon gas can run my generator?

That depends on the generator and the load. Based on rated run times, a 20L (5.3 gal) can runs an iGen2550c for roughly 40–50 hours at light load, an iGen5000c about 28 hours, and an iGen4000DFc about 22 hours. Running the A/C can roughly halve those numbers.

Can I store a gas can inside my RV?

No. Keep fuel outside the living space, upright and secured, away from heat, vents and ignition sources.

How long can I store gas for my generator?

Plan on a few months for ethanol-blended gas, longer with stabilizer or ethanol-free fuel. Date your cans and rotate the fuel.

Is a Wavian gas can CARB compliant?

Yes. The Wavian cans we sell are EPA and CARB compliant as supplied, with their spout system.

Shop the full Wavian range or browse generators. Heading off-road too? Read Best Jerry Can for Overlanding.