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How Big of Generator to Run RV AC?


An RV AC is the inside temperature-controlling unit. It provides cool air in the summer, and hot air in the winter, making it comfortable for you to use your RV in all conditions.

Nevertheless, an AC is one of the most power-demanding equipments inside an RV. You must use an external generator to run RV AC power it and other electrical appliances like a refrigerator, stove, or microwave.

Let’s see how big of generator to run RV AC you need and how to calculate the amount of power you will require.

Generator to Run RV AC

How Big of Generator to Run RV ACSince RVs are typically between 240-300 square feet, an AC with a capacity between 13.500 BTU and 15.000 BTU is enough to provide adequate temperatures. This AC capacity range can be satisfied with a generator outputting between 3000-5000 watts, depending on what other appliances use power simultaneously.

A 13.500BTU AC needs at least 3000 watts of starting power that later decreases into 1200-1500 watts of running power.

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A 15.000 BTU AC needs at least 3500 watts of starting power that later decreases into 1500-2000 watts of running power. About BTU

BTU is short for “British Thermal Units,” an energy measurement amount required to heat 1 pound of water by 1 degree Fahrenheit.

In the case of AC units, it points to their heating and cooling capacity. The more powerful the AC unit, the higher the BTU value.

Nonetheless, the power output is one of many things to consider. You must also be aware of the types of generators that exist and how they differ from each other.

Types of Generators

Types of Generators

When choosing a generator type, it’s essential to pay attention to several things:

  • How much electrical power can it output
  • How much gasoline does the generator consume
  • How much time can it keep supplying continuous power
  • How many power outlets it has.

There are several generators: portable, inverter, and standby generators. You will probably choose between a portable or an inverter generator to to run RV AC.

Portable generators

Portable generators are larger and heavier than inverter generators. They use gasoline to power an engine, which converts mechanical into AC electrical power directly fed into the generator’s control panel (the power outlets).

Depending on each model, portable generators have different power output capacities, fuel consumption, and storage.

Most portable generators output power between 3000-5000 watts. The more powerful the engine, the more power a portable generator can output and the more fuel it will consume.

Portable generators output constant power. Unlike inverter generators, they cannot control their power output according to demand.

As for the running time, most portable generators can provide continuous power between 10-20 hours.

Inverter generators

You may ask how inverter generators are different from portable generators. The main difference is how the power is generated and “cleaned up.”

In other words, inverter generators produce cleaner electrical power with lower total harmonic distortion. On the other hand, portable generators produce higher total harmonic distortion energy.

The inverter generator produces AC electricity using an engine, just like a portable generator. Then, that AC power is fed to a rectifier which converts it to DC power. That DC power is then restored to AC power via an internal computer, which is why these generators are called inverters.

Inverter generators are smaller, lightweight, and consume less fuel. The downside with inverter generators is their power output, which is often lower than portable generators. They are also more expensive than portable generators.

Standby generators

Standby generators are the largest of all types. They are unsuitable for RVs and are meant to provide power to larger facilities that perform different operations.

These generators provide a backup power solution based on natural gas or diesel. They are often stationary and placed on a solid foundation.

Their primary use is to provide power in case of power outages, and they can even operate for days, depending on their capacity.

Size Considerations

consider when choosing the generator size

What to consider when choosing the generator size

When I talk about how big of generator to run RV AC, I don’t mean the physical size but rather the size in terms of power output capacity.

Therefore, now that you know what type of generator you want, portable or inverter, it’s time to think about how powerful it should be. Your generator of choice needs to power your AC and other electrical appliances inside the RV.

The most power-demanding appliance in the RV is the AC unit. However, what if your RV has a stove, a microwave oven, a refrigerator, and a toaster?

In that case, you need to calculate the power consumption of these devices, too, to provide enough power to all of them simultaneously if required.

Here are some of the power requirements of commonly used electrical appliances inside an RV:

  • Stove – 1000 to 2000 watts
  • Refrigerator – 500 to 1000 watts
  • Microwave oven – 700 to 1000 watts
  • Toaster – 700 to 1500 watts
  • Clothes iron – 800 to 2000 watts

Other electrical appliances that are less demanding are:

  • TV – 100 to 500 watts
  • Radio – 50 to 150 watts
  • Laptop – 20 to 150 watts

How to calculate the generator wattage (power output)

To calculate a generator’s power output or wattage, you sum up each appliance’s total amount of power together.

For example, if an AC unit draws 2000 watts, a refrigerator draws 700 watts, and a stove draws 1500 watts, these devices are around 4200 watts of continuous power supply.

This means that a generator with a capacity of 4500-5000 watts can handle the power demand of these devices comfortably.

The starting watts are always higher than the running watts, which means that your generator needs to provide higher power amounts whenever a device starts up.

Therefore, if you need a constant power supply of 4000 watts, ensure your generator can handle at least 800 to 1000 watts more than that amount, to compensate for the starting power requirements.

You can also use a BTU calculator to calculate the approximate power consumption of an AC unit, depending on your RV size.


How big of generator to run RV AC depends on the power requirements of the AC unit, as well as its capacity to provide adequate temperatures inside the RV.

Nonetheless, the size of the generator also depends on the number of electrical appliances you simultaneously use.

That’s why it’s best to calculate the power consumption of each device so that you can purchase the right size and type of generator for your needs.

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