A 30 amp RV can draw at most 3,600 watts, so a generator that delivers 3,600W covers everything the rig can physically pull. That is the whole ceiling: 30 amps times 120 volts equals 3,600 watts. Buy above it and you are paying for capacity your shore power cord could never carry anyway.
In practice the decision is simpler than the math, because it comes down to one appliance.
The air conditioner decides
Everything else in a 30 amp rig is small. The converter, a 12V fridge or a fridge on propane, lights, fans, chargers, a TV: a 2,200W-class inverter generator runs all of it with room to spare. The rooftop air conditioner is the one load that forces the size question, because it needs a surge of power to start the compressor and a substantial draw to keep it running.
That gives you two honest answers:
If the AC must run off the generator: buy the 3,500W class or above. The Champion 4500 Dual Fuel (3,500W rated, 4,500W starting) is built for this. It has electric start, CO shutoff, and, importantly, a TT-30R outlet, the actual 30 amp RV receptacle, so your shore cord plugs straight in. Runs about $950 to $1,050. Honda’s EU3200i (2,600W rated, 3,200W starting) is the quieter, lighter, much more expensive alternative, and Honda pitches it specifically for a 13,500 BTU RV air conditioner. Note it uses a 30A twist-lock outlet, not a TT-30R, so you need an adapter for the RV cord.
If the AC never runs off the generator: the 2,200W class is enough. The Honda EU2200i (1,800W rated, 2,200W starting) covers everything else a 30 amp rig does, weighs 47 lb instead of 99, and is far quieter. Two catches. First, it has only 20A household outlets, no TT-30R, so you need an adapter. Second, be honest with yourself about “never”: if there is any chance you will boondock somewhere hot, undersizing now means buying twice.
What about a soft start?
Soft-start devices reduce the surge an AC compressor needs, and they genuinely move some 13,500 BTU units into 2,200W-generator territory. We are not going to promise yours will work, because it depends on your specific AC, the generator’s real surge behavior, altitude, and temperature. Treat a soft start as a way to make a marginal setup workable, not as a license to undersize on purpose.
The 10-second version
- 30A service ceiling: 3,600W. Nothing bigger is ever needed.
- Need AC: Champion 4500 class (about $950 to $1,050) or Honda EU3200i (about $2,800 to $2,900).
- No AC: Honda EU2200i class, plus a TT-30R adapter.
If you want to add up your actual loads instead of taking the shortcut, run them through our generator sizing tool. And if you are choosing between specific units, we compared eight of them spec by spec in best generators for a camper.
Specs and prices above come from the manufacturer pages linked in the sources, checked July 17, 2026.