What Size Generator for a 30 Amp RV Air Conditioner? (2026 Guide)

01The 30-amp math that decides everything

Your RV's 30-amp plug is the ceiling for the entire electrical system, and the math is simple: 120 volts x 30 amps = 3,600 watts. That is the most power everything in the RV can draw at once, air conditioner included. Two things about this number trip people up.

First, RV 30-amp service is 120 volts only. It is not the 240-volt 30-amp outlet your dryer uses at home. If you see someone sizing with 240 volts, they are answering a different question.

Second, generators wear two wattage numbers and only one of them matters for continuous loads. Rated watts (also called running or continuous watts) is what the generator can sustain under the operating conditions in the owner's manual. Maximum watts (peak or surge watts) is a short burst rating for motor startups. A generator sold as a "2,200-watt" unit, like the popular Honda EU2200i, only delivers 1,800 rated watts; the 2,200 is the surge figure. Size your continuous loads against rated watts, never the headline number. And keep the two ceilings separate: the generator's ratings describe what it can produce, while the RV's 3,600W service limit describes what the 30-amp connection can carry. A bigger generator never raises the RV's own limit.

02What your AC actually draws

An air conditioner has two appetites: the steady draw while running and the brief, violent surge when the compressor kicks on. The surge is what kills undersized generators. Here are planning figures for the three common rooftop sizes, anchored to Dometic's published installation-manual specs for the Brisk II (variant B57915.71X at 13,500 BTU: 12.4A compressor plus 2.5A fan; variant B59516.71X at 15,000 BTU: 13.3A plus 2.0A). The suffix matters: sibling variants in the same table list different locked-rotor amps, so match the full model number on your unit's nameplate.

Treat the running and surge columns as illustrative planning estimates, not nameplate specs and not manufacturer-published test results. No manufacturer publishes a single running-watt or starting-surge figure per BTU class; real draw varies with the exact model, age, voltage, and heat. The generator column is the recommendation: Dometic's manual lists 3.5 kW minimum for one rooftop unit and 5.0 kW for two, and its own footnote says these guidelines come from field experience, with total RV power usage to be considered. A 3,000W rated unit can cover the AC by itself, but it leaves almost no room for anything else running alongside; 3,500W is the safe minimum once real simultaneous loads enter the picture, which is exactly why the next section exists.

One more number worth knowing: locked-rotor amps. The B57915 lists 68 locked-rotor amps on the compressor, which times 115 volts looks like nearly 7,800 volt-amps. That is an instantaneous inrush figure, not the practical surge your generator must absorb, and volt-amps are not the same as real watts without the motor's power factor. Do not size against it or you will buy a generator twice as big as you need.

03The 3-step sizing method

The AC never runs alone. The converter is charging batteries, the fridge cycles, someone microwaves lunch. Size for the real simultaneous load:

1. Add up running watts of everything that runs together: the AC plus converter, fridge, lights, fans, and electronics. This total must stay under the generator's rated watts.
2. Add the AC's starting surge on top. Swap the AC's running watts out of the total and the surge in. This momentary peak must fit inside the generator's maximum watts.
3. Add margin. One technician recommendation, via Camping World, is sizing about 20 percent above your calculated minimum. A generator with headroom strains less than one pinned at full load.

Worked example for a 13,500 BTU unit, using scenario assumptions for the companion loads (your appliances will differ, check their nameplates): AC running 1,500W, converter bulk-charging 400W, fridge 300W, lights and fans 200W. Running total: 2,400W. With an optional 20 percent design margin that becomes 2,880W, so you want at least 3,000 rated watts. Now the surge: replace the AC's 1,500W running with its 2,800W surge and the momentary peak is 3,700W, which needs a maximum rating comfortably above that. That arithmetic is a starting point, not proof: a generator's transient response and the AC's actual startup behavior also have to fit. So the answer is at least 3,000 rated watts with a surge rating clearing 3,700W, which is why 3,500W rated is the practical safe minimum for this scenario, right on Dometic's 3.5 kW guideline for its units.

If you are comparing specific models after sizing, our generator buying guide picks through the options by use case.

04Soft starters: the 2,200W shortcut

A soft starter is a small electronic module wired into the AC that ramps the compressor up gradually instead of hitting it with full locked-rotor current. MicroAir claims its EasyStart cuts starting current by up to 65 to 75 percent versus locked-rotor amps. That is a manufacturer claim, not an independent test result, but it is what makes a 2,200-watt class generator a realistic option for a 13,500 BTU unit under the right conditions.

What a soft starter does not do matters just as much. It changes nothing about running watts. A 1,800-rated-watt generator still cannot carry a 1,900-watt continuous load no matter what is wired into the AC. And do not confuse a soft starter with a hard-start kit: the hard-start capacitor boosts starting torque and, per MicroAir's own documentation, may trim starting current by roughly 10 to 20 percent in some installations, but often shows no reduction at all. It solves a different problem and will not save an undersized generator the way a soft starter can.

If your whole plan depends on a small generator, the soft starter is the cheapest part of that plan to get right.

05Altitude and heat steal watts

Generator ratings are sea-level numbers. Honda's owner's manuals state that engine horsepower drops about 3.5 percent for every 1,000 feet of altitude. Electrical output follows the engine down, so treat what follows as an estimate, not a manufacturer-rated output: at 5,000 feet a 3,500W rated generator loses roughly 17.5 percent of its engine power, leaving about 2,900 effective watts. Remember the worked example above needed 2,880 rated watts with margin. At altitude, the same generator that was perfect at sea level is now borderline.

Heat takes its own cut on top. Hot, thin air means less oxygen per combustion cycle and harder cooling, so a generator wheezing through a 100-degree afternoon in the mountains is fighting both penalties at once. Dometic's manual says it plainly: generators may lose power at high altitudes and from lack of maintenance. If you camp high or hot, size one step up from whatever the math says, and keep the air filter and oil on schedule.

06Will a 2,000W generator run a 13,500 BTU AC?

This is the most asked version of this question, so here is the unvarnished answer: not reliably, out of the box. The "2,000-watt" generators everyone means are 2,200-watt maximum units with only 1,800 rated watts. A 13,500 BTU compressor's startup surge sails past the 2,200-watt maximum, and even the running draw near 1,500 watts leaves almost no headroom for anything else.

The qualified yes: with a soft starter installed, eco-mode off, every other significant load switched off, near sea level, in moderate heat, many owners start and run a 13,500 BTU unit on a 2,200-watt class generator. But notice how many conditions that sentence needed. Dometic still calls for 3.5 kW minimum, and if your camping involves mountains, heat waves, or a microwave running while the AC cycles, the small generator will remind you of its limits at the worst moment.

07Two small generators instead of one big one

There is a middle path. The Honda EU2200i can be paralleled: linked with a kit so two units run as one. The pair delivers up to 4,400 combined maximum watts and about 3,600 combined rated watts, which covers a 13,500 BTU setup with real margin. Only compatible models pair together, so check the manual before assuming any two units link up.

The trade is obvious. Two small generators are easier to lift, easier to store, and sip fuel when you only need one of them. They cost more than one equivalent big unit, need the parallel kit, and mean two engines to maintain and two fuel tanks to fill. For owners who cannot comfortably lift one large unit, though, two smaller ones are often the only practical answer.

08Inverter vs conventional for RV AC use

Either type runs an air conditioner if the wattage is sufficient, so this choice comes down to your campsite, not your AC. If your campground enforces quiet hours, that decides it for you. If you are comparing specific models and their trade-offs, our generator buying guide covers them, and our RV inverter guide explains the inverter side of your RV's electrical system.

09What happens when the generator is too small

It is not subtle. The compressor tries to start, the generator's overload protection trips or its breaker pops, and the AC sits there humming or short-cycling without ever cooling. Voltage sags under the strain, which is the part that costs money: electric motors hate sustained low voltage, and a compressor that keeps failing to start is being abused every time it tries. This is also how breakers get a workout and how campground neighbors learn your name.

The fix is almost never "try a bigger extension cord" or "turn off eco-mode and hope." If the surge math does not fit inside the generator's maximum watts, the honest options are a bigger generator, a soft starter, or fewer simultaneous loads. And if you are weighing generator against solar for the AC question entirely, our AC on solar guide runs the battery math so you can compare both paths fairly.

10Conclusion

For a 30-amp RV, the ceiling is 3,600 watts and the floor for air conditioning is a 3,500-watt rated generator on a 13,500 BTU unit or 4,000 watts on a 15,000 BTU unit. Add up your real simultaneous loads, respect the difference between rated and maximum watts, add margin, and size up again if you camp high or hot. A soft starter is the legitimate shortcut to a smaller generator; wishful thinking is not. Get the sizing right once and the AC just works, which is the entire point.