What Size Generator Do I Need for My RV? (A Math-Free Solution)

Good news, Reader. I’m not going to ask you to count your watts, create a spreadsheet, or whip out your pocket calculator.

Choosing the right size generator for your RV really isn’t that hard. Below, I’ve listed three sizes of generators – Small, Medium, and Large. Then I’ve described the type of person who would pick each one.

Know thyself, know your rig, and pick the category that describes you best! If you don’t know which category describes you, ask your husband/wife, and they’ll be happy to tell you.

Note: I’m going to discuss mostly portable generators. If your RV has a built-in generator, then the RV engineers already ran the numbers for you! If your old generator has kicked the bucket, just buy a replacement of the same size.

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Table of Contents

RV Generators – Super Basics

Never owned a generator before? Let me briefly explain just what they are, what they do, and why you might want one. If you already know about generators, feel free to skip ahead.

A generator is just a portable engine with an armature and a stator.

Don’t know what those terms mean? Doesn’t matter! You’re free to think of a generator as a magical box into which you pour fuel and get electricity.

Generators require fuel to operate.

  • Most portable generators use gasoline, which is readily available, but should not be stored inside an RV.
  • Larger generators, such as industrial and back-up generators, often use diesel.
  • A few portable generators use propane. Many are dual-fuel generators, meaning they can run off either gasoline and propane. However, you’ll lose about 10 percent of your power when operating off LP.

Generators make electricity.

They can make either AC (shore power) or DC (battery) electricity. Many portable generators even have their own outlets for RV 50A, RV 30A, household 20A, or USB charging.

Generators are rated in watts.

RV generator capacities range from 2,000 to 15,000 watts. The more watts, the more power the generator can produce.

Something very important to know is that generators are rated by starting and continuous wattages! The former is how much the generator can produce at maximum for a short time; the latter is how much the generator can produce continuously. Most generators are marketed by their starting wattages – their actual continuous ratings will be 10-20 percent lower.

As you’ll read later, 3,000 – 4,500 watts is a very common size for RV portable generators.

Motorhomes and luxury 5th wheels often have built-in permanent generators.

These are big, heavy diesel generators (usually a green Cummins Onan) stashed in the RV’s “basement.” They are designed to last for many, many years.

However, most travel trailers and other towables do not come with onboard generators. You’ll need to purchase a portable generator – and if you do that, may I sincerely recommend an inverter generator? I love ‘em!

Most RV owners buy generators to operate AC equipment off the grid.

If you want to run your air conditioner, microwave or coffee maker when not plugged in, for instance, you’ll either need a generator or a big inverter with a big battery bank. Since buying a generator is much easier and less expensive than upgrading your battery system, many RVers choose a generator.

You can’t run a generator willy-nilly.

Most campgrounds have quiet hours when generators are banned, such as from 10:00 p.m. to 8:00 a.m. Some localities may ban generators completely due to noise or pollution concerns. And never, ever, EVER bust out a generator while parking overnight at Wal-Mart!

Most buyers care most about noise, weight and cost.

Generator noise is measured in decibels. Below 60 dBa is best; don’t buy anything louder than 68 dBa. Most portable generators weigh between 40 and 250 lbs.

A Math-Free Approach to Choosing an RV Generator

In doing some research for this article, I noticed that many authors advocate a mathematical approach. “Calculate your appliance wattages,” they advise, “and then multiply that by your run times. Average out the results, and then select a generator with 10% more capacity to account for starting wattages.”

Ugh. Who has time to do that?

Let’s take a different approach. I’m going to show you some common generator sizes and tell you what they can run at one time. From there, you can work backwards, and choose the best size for your power needs – no math required!

Well, maybe a teeeny bit of math. For instance, it might be helpful to know that:

  • A 30A shore power connection can provide up to 3,600 watts of power
  • A 50A shore power connection can provide up to 12,000 watts of power

So a 4,000-watt generator (which usually supplies 3,200-3,400 watts continuously), is almost the same as plugging into a 30A RV power pedestal!

So if you own a 30A travel trailer, congrats! You can buy a portable generator that provides full power 🙂

However, as I’ll explain later, very few portable RVs can provide 12,000 watts of power.

So if you own a 50A motorhome, then unfortunately, your generator will probably not provide full power (unless you buy two!) More on that below ….

One Last Note Before I Begin …

Honda EU 2200i Inverter GeneratorI’m a total fanboy for inverter generators. Compared to conventional open-frame generators, they are quieter, more efficient, and less polluting. They also generate higher-quality electricity, good for running sensitive machines like CPAP machines.

Regardless of what size generator you pick, I highly recommend spending the extra money on an inverter generator.

Common Generator Sizes by RV Type

RV TypeGenerator Size
Mini Camper<2,200 Watts
Travel Trailer2,000 - 5,000 Watts
5th Wheel/Toy Hauler3,500 - 7,000 Watts
Class B Van2,000-3,600 Watts
Class C Motorhome3,500 - 5,000 Watts
Class A Motorhome5,000 - 7,000 Watts

Do You Need a 2000-Watt Generator? (Small)

  • Size range: 1,800 – 2,800 watts
  • Type: Conventional portable generator | inverter generator
  • Fuel type: Gas, diesel, LP
  • Best for: Minimalist boondockers

There’s a lot to love about small generators! They’re easy to carry, hard to hear, and they sip gasoline like a teetotaler drinks vodka.

However …. every RVer looking at a small generator just has one question:

Can I run my RV air conditioner off a 2000-watt generator?

Ehh … not likely. However, there are three exceptions to this rule:

  1. If you have a small RV air conditioner, between 8,000 and 11,000 BTUs, and you run your A/C on medium (you might also need a soft-start).
  2. If you have a high-efficiency medium RV air conditioner, between 11,000 and 13,500 BTUs, and you have a soft-start capacitor, and you run your A/C on medium/low.
  3. If you have a window air conditioner, between 5,000 and 8,000 BTUs, which are often installed in teardrop campers.

However, you will often find that starting an air conditioner while running anything else will trip a breaker and shut everything down. Or that you can run the A/C on Low or Medium, but not on High. Or that you can’t run your microwave at the same time.

See what I’m saying? Small generators are best for boondockers who want to run everything EXCEPT an air conditioner: computers, microwaves, coffee makers, small refrigerators, etc.

My recommendation is that if you plan to run a rooftop RV air conditioner, get a generator rated for at least 2,400 watts. If you want to run two air conditioners … well, keep reading!

Note: I promised I wouldn’t do any math .. but … this is good stuff! A 2000-watt generator normally has a 1,600-watt continuous rating, which is about 15 amps at 110 volts. So a 2000W generator can produce as much electricity as a single household outlet.

Do I Need a 3,500-Watt Generator? (Medium)

  • Size range: 3,000 – 4,500 watts
  • Type: Conventional portable generator | inverter generator
  • Fuel type: Gas, diesel, LP
  • Best for: Most RVers!

We are now in Goldilocks territory: Not too big, not too small. Most RVers will be very happy with a 3,000 to 4,500 watt inverter.

As I mentioned earlier, a 30A RV plug provides 3,600 watts of power, which means a 4,000-watt generator (usually 3,200 to 3,400 running watts) provides almost as much power as a 30A shore power connection! Wahoo!

With a generator of this size, you can operate a single air conditioner, a microwave, a TV, a computer, and charge your batteries – all at the same time! (A hair dryer might overdo it, though).

Can you run two air conditioners on a generator this size? Eh … it’s a close call. Two 15k BTU units without soft-start capacitors would be a stretch. If you regularly run two air conditioners, I think you’d be happier with the next size up.

You also might need a larger generator if your RV has a large residential-style refrigerator rather than an RV absorption refrigerator.

Pro Tip: If you can stay below 3,600 watts, you’ll get a much quieter generator.

Hot Hint: Again, I highly recommend an inverter generator! A medium-sized model will fit inside a 2-ft cube and should weigh less than 100 lbs.

Do I Need a 5,000-Watt Generator? (Large)

  • Size range: 5,000 -7,000 watts
  • Type: Conventional portable generator | inverter generator
  • Fuel type: Gas, diesel, LP
  • Best for: Anyone running two air conditioning units or full-size AC/DC refrigerators

Generators producing between 5,000 and 6,600 watts are true workhorses. These create more power than a 30A RV could ever use, and about half the power of a 50A power pedestal connection. You can live a life of ease and run two air conditioners to your heart’s content. You probably won’t blow a breaker unless you’re running your washer and dryer at the same time, too.

You might need a large generator if your RV has AC/DC refrigerator, too. A full-size 110-volt fridge/freezer can draw 15 amps (about 1,600 watts) all on its own!

Large portable generators also typically have built-in 50A RV receptacles, so you can plug in without a second thought. Most can produce either 120 or 240V power with the flip of a switch.

There are trade-offs to this excessive power, however.

  • They are loud! Usually about twice as loud as a Small or Medium generator.
  • They burn more fuel because of their bigger engines.
  • They are heavy! Most weigh at least 120 pounds. Some weigh as much as 220 pounds!

This is also the maximum size of most inverter generators, such as the Honda EU7000, Yamaha EF6300, and the Champion 4500W series. Beyond this capacity, you’ll get much louder, much heavier open-frame conventional generators.

What About Generators Larger than 6,000 watts?

When it comes to generators above 7,000 watts, I question the definition of the word “portable.” Most of these generators weigh at least 200 pounds! They’re big, gas-guzzling, eardrum-splitting, open-frame monsters that won’t even fit inside many RV storage compartments. (And the RVs that can accommodate them, such as Class A’s, usually already have their own onboard generators.)

These monstrosities are “portable” in the sense they have wheels and can be dragged a few feet. Or they can be hoisted by contractors into the back of a pickup truck. They’re not “portable” in the RV travel sense, I think.

Not to hop on my soapbox, but do you really need a generator larger than 6,000 watts, anyways? That’s enough to run two 15k BTU air conditioners and a TV! By RV living standards, that’s richer than Solomon.

If you really need more than 6,000 watts, just buy two inverter generators. Most gennies can be wired in parallel with a kit sold by the manufacturer. Many RV travelers, for instance, wire two 3,500-watt generators to service a 50A motorhome.

Why Do It the Hard Way?

There’s really no point in calculating all your kilowatt-hours when selecting an RV generator.

Most of that math is wasted. A laptop, for instance, might draw 65 watts. A 15,000-BTU air conditioner, meanwhile, can draw up to 1,800 watts! (That’s 27 laptops!)

There are only appliances that demand the majority of your power:

  • Air conditioners*
  • Microwaves
  • Refrigerators* operating on AC or DC electricity
  • Any heat-making appliance (coffee maker, hair dryer, etc.)

(I’m assuming you’re operating your furnace, water heater and stove off propane.)

And of these four, only two run more or less continuously: the air conditioner and the refrigerator. And both of these deserve special attention because they use compressors, which can draw 2-3x their running power at startup!

That’s why there’s not much point in tracking down every stray watt. Just count your A) air conditioners and B) compressor-operated refrigerators.

  • If zero, get a small generator.
  • If one or two small units, get a medium-sized generator.
  • For two or more medium-sized units, get a large generator. Save yourself the mental sweat.

When in doubt, go up a size, or buy two small generators and pair ‘em up!

RV TypeGenerator Size
Mini Camper<2,200 Watts
Travel Trailer2,000 - 5,000 Watts
5th Wheel/Toy Hauler3,500 - 7,000 Watts
Class B Van2,000-3,600 Watts
Class C Motorhome3,500 - 5,000 Watts
Class A Motorhome5,000 - 7,000 Watts

Recap – My Advice on Choosing the Best Size Generator for Your Camper

  • If you’re a minimalist boondocker who thinks air conditioning is the opioid of the bourgeoisie, get a Small (1,800W – 2,800W) generator.
  • If you own a typical RV with one air conditioner that you use and thank God for, get a Medium (3,000W – 4,500W) generator. Err on the larger side if you run an AC/DC fridge or lots of kitchen appliances.
  • If your RV makes people scream “Godzilla!” and cower in fear, get a Large (5,000-7,000W) generator, or pair two medium-sized ones.
  • If your RV engineers had the good sense to install a permanent generator in your toy hauler/5th wheel/motorhome, then don’t deviate.

Ross

RV engineer by day, intrepid blogger by night (and occasionally weekends). This website is all about how RVs work, and sometimes why they don't. Bookmark pages that you find helpful, and join my email list for exclusive monthly awesomeness.