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What Size Generator Do I Need for My RV?

You need electricity to keep things running when you’re not hooked up to shore power, but how much? How many watts does it take to power up your AC or appliances? There are a few essential variables to consider when deciding what size generator for your RV.

Let’s find out more about generators and what they can or can’t handle.

What Is An RV Generator?

An RV generator usually refers to an engine-driven machine to convert fuel into electricity. Most RVs have a few different ways to generate electricity. Onboard batteries are used to store energy but need outside sources to charge them. Most RVs get some charge from the RV engine or tow vehicle alternator. Many RV’s also have solar panels to replenish them. Another vital power source many RV’s have is a generator, which runs on gas, diesel, or propane and generates 120-volt electricity.

A generator is rarely an RV’s only power source, but in some ways, it acts as a safety net. It’s what makes an RV genuinely self-contained. When your batteries run down, you can turn to your generator when you aren’t hooked up to shore power. It will provide AC power immediately and reliably as long as it has fuel.

Some RVs have built-in generators that are designed to run the entire RV. Many of these built-in units can even be run while you are driving. If you don’t have one, it’s easy to put a portable generator into service as an additional power supply. You can also run more than one, in parallel, if you need.

Pro Tip: If you are new to generators learn all about them by reading our Complete Guide To RV Generators.

honda generator
This is our portable honda 2000 generator

RV Generator Sizes

To help you decide what size generator for your RV, let’s look at what’s out there.

Manufacturers usually rate generators in terms of the watts they generate. (Sometimes, you’ll see this listed as kilowatts instead.) Most RV generators fall within a range of 1,500 to 12,000 watts, which equals 1.5 to 12 kilowatts.

Here is a collection of the most popular and high-rated RV generators on the market.

Portable RV Generator Sizes

Standard sizes for portable generators for RVs are 2,000 to 4000 watts but can be as large as 12,000 watts. Bigger is better in some situations, but bigger also means heavier, less fuel-efficient and noisier. No one wants to pack extra pounds on an RV unless it’s necessary.

Traditional-style construction generators are the most powerful and cheapest but shouldn’t be your first choice for an RV because they’re noisy, less fuel efficient and prone to power surges. Inverter generators are quieter and more efficient. They also have microprocessors that regulate their voltage and current to protect sensitive electronic devices like computers and cell phones.

Pro Tip: Learn more about What Is An Inverter Generator?

Built-In RV Generator Sizes

Many larger RVs have built-in generators inside a compartment. They draw directly from the fuel tank or burn propane, and you can safely use them during transit. You can also program them to automatically turn on and off or integrate them into your appliances’ wiring systems. Sizes vary, but they’re usually at least 3,000 watts with a maximum of 12,000 watts in most RV’s.

Built-In Onan RV Generator 5500 watt size
Built-In 5500 watt Onan Generator

How Many Watts

So, how many watts will you need?

Well, you won’t be running all your appliances and accessories on your RV generator at once, but you should know how much they use. Electric ranges and water heaters are major power hogs, requiring around 2,000 watts each. By comparison, a refrigerator uses 600 to 800 watts.

You will need to know these numbers to better select the appropriate generator size for your RV lifestyle.

Did You Know: You can’t use a generator everywhere you travel. Learn more about California’s Generator Ban.

What Size Generator Do I Need for a 30-Amp RV?

Some RVs have 30 amp electrical service, and others have 50 amp. The difference is how much power the RV can draw based on amperage and voltage. 

To determine this maximum amount, multiply the number of volts (120) by the number of amps (30). The total is 3,600, so a 3,600-watt generator will power everything just like you are on shore power.

Anything more significant would be overkill; it wouldn’t be dangerous to use it, but you don’t need it. It’s not required to have a 3600-watt generator however, you just won’t have the same capacity as on-shore power and might need to limit your power use.

What Size Generator Do I Need for a 50-Amp RV?

Using that same formula, the magic number of maximum watts is 12,000. But you can easily get by with a generator much smaller than that. In fact, it would be hard to consume that much energy, even if you run everything at the same time. A more realistic range for a 50-amp RV is 4,000 to 8,000 watts.

Although the RV can draw this much power even a 2000 watt generator can be used on a 50 amp RV, you will just need to be aware that you will be power limited. If you exceed the power the generator can put out it will overload and shut down the generator.

Portable Generator plugged into a 50 Amp RV
Portable Generator plugged into a 50 Amp RV

How Big of a Generator Size Do I Need to Run an RV Air Conditioner?

Whether it will run the AC is another critical factor in determining what size generator you need. In fact, many RVers have a backup generator, so they can run the AC when necessary.

It’s a fact of RV life that air conditioning units use a ton of power. The standard 15,000 BTU RV air conditioner draws around 1600 watts but may surge upwards of 3000 when starting.

Pro Tip: We crunched the numbers to determine How Long Can You Run an RV Generator Continuously?

Will a 2000-Watt Generator Run an RV Air Conditioner?

Most 2000-watt generators will struggle with a 15k AC but are usually ok on 13.5k. Keep in mind that you won’t be able to run much else and might even need to turn your battery charger off to use it. Because of this, a generator of 3000 watts is a good choice if you want to run an AC off of it.

An air conditioner uses electricity to run its fan and also its compressor. Sometimes it will seem like an AC is running just fine, and then the compressor comes on, and it shuts everything down. It indicates you don’t have enough power. 

Some people solve this problem by running two smaller generators in parallel. Doing so requires carrying twice as much weight on board. It also means twice the amount of fuel and doubles the noise.

Sometimes its the compressor kicking on will overload the generator even if it can run the air conditioner. Some people install “Soft Starts” on their air conditioners to limit this startup draw and the generator can then start and run the air conditioner.

honda portable generator on slide
Some RV’s build special compartments for portable generators

Other Considerations When Selecting an RV Generator Size

How many watts it puts out is just one factor in choosing a generator for your RV. Here are some other factors to consider besides what size generator you need:


For many RVers, price is essential. Expenses of RV living add up quickly, and you’re likely watching your budget closely and carefully. With that said, going cheap on a generator can mean having to spend more down the road to replace it with something more suitable.

Generally speaking, the bigger the generator, the more expensive it will be. High-wattage Onan generators for example can run from $3000 to over of $10,000.


Inverter-style generators are usually quieter because they’re inside an insulated casing. It’s designed to muffle that annoying whine of older generators. To keep peace with your neighbors – and to keep yourself sane – it pays to look for one that has a good noise rating.

And as a reminder, observe the generally accepted “quiet hours” whenever possible.

Weight (If Portable)

Keep weight in mind along with watts. As we said before, there’s a reason why lower-powered models like 2,000 and 2,200-watt generators are so popular. They’re relatively light, so one person can move them around, and they’re less likely to overload your RV.

Fuel Type

If your RV runs on diesel, it makes sense to get a generator that runs on diesel, too. That way, you don’t have to haul around an extra fuel container or make an extra run to the station. The same goes for gasoline.  

Another option is propane, which many prefer over gas and diesel. Others, however, would rather conserve it for other uses. Many manufacturers offer “dual fuel” capabilities that burn either gas or propane, which would be perfect if you want flexibility. 

motorhome generator compartment open while driving
The generator in our motorhome is diesel, the same fuel the coach burns. It draws fuel from the same tank but will cutout when the fuel drops below 15 percent.

Find the Best Size Generator For Your RV

Hopefully, after reading this article, you have fewer questions regarding what size generator to get for your RV. There’s a lot to consider when making such an important decision, so do your homework. It’s the only way to find out what’s best for your situation.

If you feel you need to understand more about RV Generators, head on over to The Complete Guide To RV Generators where we cover everything from generator types to troubleshooting and maintenance.

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Off We Go

Sunday 5th of March 2023

Hello! I have a puzzling question not sure if you can help I have a Silvercrown. It's like a Renegade or a Super C. It's on a Freightliner Chassis. We no longer wish to use our onboard generator. We purchased 2 3600 watt predator generators and Nothing power. We don't plan to run ac. But nothing seems to charge the inverters. Any advice?

Mortons on the Move

Sunday 26th of March 2023

The neutral is probably not bonded in the generator and you might have an onboard EPS system shutting it down. You probably need to make a neutral bonding plug.

Michael Clark

Thursday 2nd of June 2022

Generators come in a variety of sizes, and you'll need one that can power your appliances. The amount of electricity required varies based on the individual's needs; for some, a 3,000 to 3,600-watt generator is sufficient.

John Peters

Saturday 13th of November 2021

RV owners must have a power supply for their car in order to continue enjoying RVing. As a result, knowing what size generator to use for a 50 amp RV is critical. Thank you for making this information available to us.

Scott Wenhe

Friday 24th of September 2021

Hello. We are considering a truck camper (1172). My question is regarding the power supply. How did the lithium batteries/solar package work out? Did you have sufficient power to run the A/C unit while running other appliances, computer etc.? How long did the batteries last under load? I am torn between the generator option (3000 Honda inverter) and the battery option you chose to go with in the Lance. I would love to hear your feedback.

Mortons on the Move

Monday 7th of March 2022

For running AC off grid, the battery system would not last long. We never ran the AC except to test if it would. Otherwise the system is perfect! Check out our new build with the 12V AC unit, that can run on the batteries all day.