What size generator for a 50 amp RV with 2 AC units?
Two 15,000 BTU air conditioners (2,500 W running each, top of Champion’s range) plus about 1,500 W of other loads is 6,500 W running. Plan on a generator with 8,125 W running and 8,500 W starting watts, with a 120/240 V 14-50R outlet.
How to work it out
- 2 × 2,500 W AC + 1,500 W other = 6,500 W running × (1 + 25%) = 8,125 W
- Starting: 6,500 W + one AC start (4,500 − 2,500 W) = 8,500 W
- 50 A service: 2 legs × 120 V × 50 A = 12,000 W
Big fifth-wheels and motorhomes with 50 amp service often have two or three air conditioners. A 50 amp rig can draw up to 12,000 W across its two legs, but you rarely need a generator that big — just one that covers what actually runs at once.
Adjust for your project
More options: Headroom
- Running watts
- 8,125 W
- Starting watts
- 8,500 W
- Running watts, all together
- 6,500 W
- Most your RV service can draw
- 12,000 W
- Share of the service in use
- 54%
- Per 120 V leg (50 A)
- 3,250 W and 3,250 W (6,000 W each at most)
- A 50 A RV draws from two separate 120 V legs, up to 6,000 W each; air conditioners are often split between them. A generator with a 14-50R outlet must also be rated to supply the load — the outlet shape alone doesn’t mean 50 A per leg.
Generator size by number of air conditioners
| Air conditioners running | Running watts | Starting watts | Share of the service in use |
|---|---|---|---|
| 0 | 1,875 W | 1,875 W | 13% |
| 1 | 5,000 W | 6,000 W | 33% |
| 2 | 8,125 W | 8,500 W | 54% |
| 3 | 11,250 W | 11,250 W | 75% |
What to know about generators for 50 amp rigs
- The outlet must match. A 50 A RV plugs into a 14-50 (120/240 V) outlet. Champion’s 8500 W inverter, for example, has a 14-50R — but its rating, not the outlet shape, sets how much each leg can supply.
- Two legs, split loads. Each leg can carry up to 6,000 W. Rigs with two ACs often have one on each leg, which balances the generator.
- Stagger the starts. If the two ACs never start in the same instant (some rigs have load management for this), the generator only has to cover one start at a time, as assumed here. If they can, add the second start.
- One AC at a time halves it. Running one 15,000 BTU AC plus the same other loads needs about 5,000 W running.
The 30 amp version is on what size generator for a 30 amp camper; fuel for a big generator is on how long a generator runs on a 20 lb propane tank. How the services differ is in 30 amp vs 50 amp RV.
Different size? Use the full RV Generator Size Calculator.
What you’ll need
- Dual-fuel portable generatorPremium price
Runs on gasoline or propane. Propane stores for years without going stale; expect somewhat fewer watts on propane.
See options on Amazon (opens in a new tab) - 50 A RV surge protectorMid-range price
The 50 A version for rigs with two 120 V legs. Some models also flag low voltage from a struggling generator.
See options on Amazon (opens in a new tab) - Battery-operated carbon monoxide alarmBudget price
CPSC advises battery or battery-backup CO alarms whenever a generator is in use. Look for UL 2034 certification and test monthly.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
What size generator for a 50 amp RV with one AC running?
About 5,000 W running and 6,000 W starting watts.
What size generator for a 50 amp RV with 3 AC units?
About 11,250 W running and 11,250 W starting watts — 75% of the 12,000 W service.
Other common sizes
- What size generator for a 30 amp camper — 3,250 W running / 4,100 W starting
Sources
- Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).
- Champion Power Equipment — 3500-Watt Dual Fuel Generator (model 201213) specifications (opens in a new tab) — 3,500 running / 4,000 starting watts on gasoline; 14 h at 50% load on 4.7 gal; 10.5 h at 50% load on a 20 lb propane tank; 120 V 30 A TT-30R RV outlet.
- Champion Power Equipment — 8500-Watt Dual Fuel Inverter (model 201175) specifications (opens in a new tab) — 120/240 V 14-50R outlet — the plug shape a 50 A RV uses.
- U.S. Consumer Product Safety Commission — Portable Generator Hazards (Safety Alert 5123, 2021) (opens in a new tab) — Never run a generator indoors or in a garage, even with doors open; place it outside far from doors, windows and vents; CO alarms; never “backfeed” by plugging into a wall outlet.
- U.S. Consumer Product Safety Commission — CPSC Warns Consumers in Path of Storms to Take Precautions When Using Portable Generators (July 24, 2020) (opens in a new tab) — “Use your generator OUTSIDE your house ONLY, at least 20 feet from your home”; make sure you have working CO alarms.