What size generator for an RV?
30A vs 50A reality, common loads (AC, microwave, converter), quiet inverter vs open-frame — then check your list on the free calculator.
Quick sizing for the roof air conditioner: 13,500 BTU RV AC and 15,000 BTU RV AC.
RV electrical reality (30A vs 50A)
A 30 amp RV uses a single-leg shore cord. Buying a generator far above what that cord can pass does not help through the TT-30 path. A 50 amp RV uses a two-leg shore cord and a higher ceiling, but two air conditioners plus appliances still need a wattage list. Amp rating alone is not a generator size. This page stays on generator sizing; house transfer-switch guides are for home panels, not coach shore power.
Common loads (method, not brand claims)
| Load | How to size |
|---|---|
| Roof AC | Nameplate running watts + compressor start (or soft-start reduced start). Compressor surge usually sets the generator class. |
| Microwave | Nameplate watts — often the biggest non-AC spike on no-AC boards. |
| Converter / charger | Continuous draw while charging the house batteries; add to running total when on. |
| Fridge | Absorption fridge versus a residential alternating-current fridge — use the mode you will run on the generator; see also the fridge and freezer guide. |
Cite your appliance labels and the calculator presets — do not invent brand wattage demos. Label any measured campground demo NEEDS_HOUSE_PROOF until verified.
Quiet inverter vs open-frame
Campground noise rules and neighbors favor inverter generators. Open-frame units often deliver more watts per pound for dual-AC 50 amp coaches. Match class after sizing — then browse the best portable generators list by wattage tier, not by marketing labels.
Headroom, altitude, and heat
Apply the headroom you set on the calculator above peak (running watts plus the largest surge). Generators lose capacity at altitude and in high heat. If you boondock in mountains or desert summers, derate per the manufacturer's guidance or the altitude tool. Propane ratings are often lower than gasoline ratings; check the propane rating against the air-conditioner start.
CTA and related
Build your RV load list on the free generator size calculator. Cross-links when useful: fridge & freezer · portable generator classes. A campsite fan, laptop, and radio, sized apart from roof air conditioning, is on best portable generator for camping. Towing weight for the trailer is a different calculation: TrailerTowCalc.
If the RV is a travel trailer rather than a motorhome, pair the generator choice with towing a new travel trailer safely before the first trip.
Running a whole 30 amp coach? See what size generator for a 30 amp RV.
FAQ
Can a small inverter run RV air conditioning?
Usually not reliably with other loads. Roof air-conditioner compressors spike well above running watts at start. A small inverter can cover lights, the fridge, the converter, and a microwave without air conditioning. For air conditioning, plan a larger class or a soft-start kit, then verify with the nameplate and the free calculator.
Do I need dual fuel on the road?
Dual fuel (gas/propane) helps for boondocking when you can tap the coach propane tank and avoid extra gas jugs. Expect some wattage de-rate on propane — check the model's propane rating clears your AC or microwave surge, not only the gasoline rating.
What size generator for a 30 amp vs 50 amp RV?
A 30 amp shore cord and a 50 amp shore cord are different pedestals, not a generator size. A 50 amp coach has two legs and a higher ceiling. Dual air conditioners still need a wattage list. Size to the loads that will run together, not to the pedestal amp alone.
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After the calculator names a class, compare a dual-fuel inverter in that class and a soft-start kit for the roof air conditioner.
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Sources & Standards
Method context (not a design stamp):