RV Generator Wattage Calculator

Use this RV generator wattage calculator to estimate the running and starting power your RV may require. Select your air conditioner, refrigerator, converter, microwave and other appliances, then enter your camping elevation.

The calculator accounts for startup surge, elevation-related power loss and operating headroom—not merely the combined running wattage. If you need help interpreting the result, read our guide to choosing the right generator size for an RV air conditioner.

After calculating the wattage your RV requires, use the propane generator runtime calculator to estimate how long your selected load may operate on a 20-pound tank.

Your calculated running and starting requirements can also be used to evaluate a portable battery system. Compare them with the inverter ratings in our guide to the best portable power stations for RV air conditioners.

Also, see our generator altitude derating calculator to determine whether the generator can still supply those watts at your campground’s elevation.

How the RV Generator Wattage Calculator Works

The calculator begins by adding the continuous wattage of every selected appliance. It then adds the largest likely single startup surge, adjusts the result for elevation and includes extra operating capacity.

This produces three useful numbers:

• Continuous load: The combined power required while your selected appliances are operating normally.
• Peak demand: The continuous load plus the largest anticipated startup surge.
• Recommended generator class: A practical generator size that includes elevation adjustment and operating headroom.

The calculator does not add every appliance’s starting wattage together. In normal use, all of your motor-driven appliances are unlikely to start during the same instant. It instead adds the largest startup surge to the combined continuous load.

This provides a more realistic estimate than adding every maximum rating together, but the result is still a planning estimate. Check the electrical data plate or owner’s manual for each appliance before purchasing a generator.

Once you know the load your RV requires, enter that wattage in the Quiet Campsite Generator Planner to estimate campsite noise, fuel runtime and generator placement.

Why Starting Watts Matter in an RV

Some RV appliances require considerably more power when starting than they consume during normal operation. Air conditioners and compressor-driven refrigerators are the most common examples.

A 13,500 BTU RV air conditioner might use approximately 1,500 watts while running but require several thousand watts briefly when its compressor starts. A generator could have enough continuous output to operate the air conditioner but still overload during compressor startup.

This is why you should compare both the running-watt rating and starting-watt rating when choosing an RV generator.

If compressor surge is the reason your calculated generator requirement is so high, learn how an RV soft start changes generator requirements. The guide also explains why a soft start reduces starting demand without materially reducing the A/C’s continuous running load.

For a real-world example, see Can the Honda EU3200i Run a 13,500 BTU RV Air Conditioner?. The answer depends on the air conditioner’s starting requirements, camping conditions and whatever other appliances are operating.

How an A/C Soft Starter Affects Generator Size

A properly installed soft starter can reduce the initial surge required to start an RV air conditioner. This may allow the air conditioner to start more reliably on a smaller inverter generator, especially when other minor loads are operating.

A soft starter does not reduce the air conditioner’s normal running wattage by the same amount. High temperatures, elevation and the condition of the air-conditioning system can also affect performance.

Do not assume that adding a soft starter guarantees that every generator can operate every air conditioner. Check the specifications for the exact air conditioner, soft starter and generator combination.

How Elevation Affects Generator Output

Portable generators generally produce less usable power at higher elevations because their engines receive less oxygen. This calculator estimates a 3.5% power reduction for every 1,000 feet above the first 1,000 feet.

For example, a generator rated at sea level may not provide its full advertised output at a mountain campground. The generator may need to work harder, and an air conditioner that starts reliably near sea level could become more difficult to start at higher elevation.

Consult the generator manufacturer’s elevation-derating and carburetor-jetting instructions before relying on a generator near its maximum capacity.

Elevation is not the only environmental factor that matters. Extreme heat can increase air-conditioner demand, while the generator’s fuel type, maintenance condition and extension-cord losses may further reduce available performance.

Can You Run an RV Air Conditioner and Microwave Together?

Possibly, but the combined load can exceed the capacity of many smaller RV generators. A microwave may draw approximately 1,200–1,600 watts while operating, even if its advertised cooking output is lower.

For a smaller generator, the more practical approach is usually to turn off the microwave and other large loads while the air conditioner is operating. You may also need to reduce converter charging demand before starting the air-conditioner compressor.

Managing large loads individually may allow you to use a smaller, quieter and more fuel-efficient generator.

The Honda EU3200i RV and home-backup wattage guide provides examples of realistic appliance combinations rather than considering every appliance separately.

If your calculation indicates that you need a larger unit, compare the best quiet 4,500-watt inverter generators for RV air conditioners. This generator class provides more flexibility for operating an RV air conditioner alongside smaller supporting loads.

Verify Your RV’s Actual Wattage Before Buying

The calculator uses practical default estimates, but electrical requirements vary substantially between RVs. Before purchasing a generator:

• Check the electrical data plate on the air conditioner.
• Confirm the microwave’s electrical input wattage—not only its advertised cooking wattage.
• Check the refrigerator’s wattage in electric mode.
• Consider how much power the converter may draw while charging depleted batteries.
• Include any television, coffee maker, battery charger or other appliance you expect to operate.
• Compare the calculation with both the generator’s running-watt and starting-watt ratings.
• Account for whether the generator will operate on gasoline, propane or natural gas.

Dual-fuel and tri-fuel generators commonly provide less output on propane or natural gas than they produce on gasoline. Use the rating for the fuel you actually plan to use.

If you are deciding between different power sources, our quiet inverter generator vs. portable power station comparison explains the differences in noise, runtime, indoor usability, charging and high-wattage appliance support.

If you plan to meet the calculated requirement with two smaller generators, do not simply add the wattages printed on their cases. Read how to calculate usable wattage from parallel inverter generators, including running-watt, surge and outlet-amperage limits.

Important Generator Safety Warning

Never operate a portable generator inside an RV, garage, storage compartment or other enclosed space. Place it outdoors, well away from doors, windows and vents, and follow the generator manufacturer’s required clearances.

Use working carbon-monoxide alarms inside the RV. Never create a homemade generator enclosure unless it provides the ventilation, exhaust clearance and fire protection required by the manufacturer.

If you expect to provide power for several hours or overnight, read Can You Run an Inverter Generator Overnight? before doing so.

You can reduce generator noise, but noise control must never interfere with cooling airflow or exhaust dispersal. Follow the safe methods in How to Make a Generator Quieter—Without Creating a Safety Hazard.