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What Size Generator for an RV or Camper? 30 Amp and 50 Amp Sizing
Most RVs with one 13,500 or 15,000 BTU air conditioner need a generator of at least 3,500 watts. That is Dometic's own minimum generator size for one of its rooftop units, and 5,000 watts for two. Honda's guide puts a 13,500 BTU RV air conditioner at about 2,800 starting and 1,800 running watts. A 30 amp RV can use up to 3,600 watts, and a 50 amp RV up to 12,000 watts.
30 amp vs 50 amp RV: how many watts?
| RV service | Plug | Maximum watts | Typical setup |
|---|---|---|---|
| 30 amp | TT-30 (one 120V hot) | 3,600 W | One air conditioner |
| 50 amp | 14-50 (two 120V hots, 50 A each) | 12,000 W | Two air conditioners |
Source: Camping World, "30 Amp vs 50 Amp: What's the Difference?" Check the plug on your shore power cord to see which you have.
RV air conditioner watts (manufacturer specs)
The air conditioner sets your generator size, because it has the biggest startup surge in the rig.
| Unit | Cooling | Compressor running amps | Fan amps | Locked rotor amps | Dometic minimum generator |
|---|---|---|---|---|---|
| Dometic B57915.71X | 13,500 BTU | 12.4 A | 2.5 A | 68.0 A | 3.5 kW (1 unit) / 5.0 kW (2 units) |
| Dometic B59516.71X | 15,000 BTU | 13.3 A | 2.0 A | 70.0 A | 3.5 kW (1 unit) / 5.0 kW (2 units) |
Source: Dometic rooftop air conditioner operating instructions (models 457915, B57915, 459516, B59516), 120 VAC. Dometic notes these are general guidelines. Locked rotor amps is the current the compressor pulls for an instant at startup.
| Load (Honda wattage guide) | Running watts | Starting watts |
|---|---|---|
| RV air conditioner, 13,500 BTU | 1,800 W | 2,800 W |
| RV air conditioner, 15,000 BTU | 2,000 W | 3,300 W |
| RV refrigerator | 180 W | 600 W |
| Microwave (1,000 W) | 1,500 W | 1,500 W |
| Coffee maker | 600 W | 600 W |
Source: Honda Power Equipment generator wattage estimation guide. Champion's chart gives a wider range for a 13,500 BTU unit: 1,500 to 2,000 running and 2,800 to 3,500 starting watts.
What size generator for your RV? (worked examples)
Add up the running watts, then add the extra starting watts of the air conditioner (starting minus running), since it has the biggest jump. A Progressive Dynamics PD4655 converter (55 amp) is rated at up to 950 watts of AC input while it charges your house batteries.
| What you want to run | Running watts | Peak watts |
|---|---|---|
| One 13,500 BTU AC | 1,800 W | 2,800 W |
| 13,500 BTU AC + RV fridge + converter charging | 2,930 W | 3,930 W |
| 13,500 BTU AC + RV fridge + 1,000 W microwave | 3,480 W | 4,480 W |
| Two 15,000 BTU ACs (50 amp RV) | 4,000 W | 5,300 W |
| Two 15,000 BTU ACs + fridge + microwave + converter | 6,630 W | 7,930 W |
Figures from Honda's guide and the PD4655 manual. A 30 amp RV tops out at 3,600 watts no matter how big the generator is, so the third row is about the most a 30 amp rig can run at once.
Tip: a soft starter cuts the air conditioner's startup surge. Micro-Air says its EasyStart reduces starting current by up to 75%, which lets a smaller generator start the AC.
Generators for RVs
A 120/240V generator feeds a 30 amp RV from one of its two 120V legs, so only about half of its running watts reach a 30 amp plug. A 50 amp RV uses both legs. In-stock picks:
- DuroMax XP9500iH: 9,500 starting / 7,600 running watts on gasoline, inverter power under 3% THD, and a 14-50R outlet that takes a 50 amp RV cord. About 3,800 running watts per leg covers a full 30 amp RV through an adapter. Dual fuel, CO alert shutoff. $1,999
- DuroStar DS8000iX: 8,000 starting / 6,500 running watts, inverter power, L14-30R outlet. Its spec sheet lists 27.08 A per leg at 240V, about 3,250 running watts on one 120V leg. That covers a 30 amp RV with one AC, the fridge, and the converter (rows 1 and 2) through an L14-30 to TT-30 adapter. $999
- DuroMax XP13000EH: 13,000 starting / 10,500 running watts on gasoline, 14-50R and L14-30R outlets. The most power for a 50 amp coach with two ACs. Not an inverter model. $1,299
Adapters are sold separately. Keep the generator away from open windows, doors, and vents. For quieter campsites, see inverter generator vs regular generator and our guide to inverter generators for camping. Browse all inverter generators.
Can a power station run an RV air conditioner?
A big one can, for a short time. The Jackery HomePower 3000 (3,072 Wh, 3,600 W output, 7,200 W surge) covers a 13,500 BTU AC's 2,800 starting watts and runs it about 1.5 hours at 1,800 W (3,072 x 0.9 / 1,800). From $1,349. For fridges, lights, and fans without the AC, see Best Solar Generators for Camping and RV.
Need help sizing? Call 1-888-855-7286. Tell us your RV's plug (30 or 50 amp) and how many air conditioners it has, and we will match you to the right generator.
RV generator FAQ
What size generator do I need for a 30 amp RV? At least 3,500 watts for one rooftop AC, per Dometic's minimum. A 30 amp RV can use up to 3,600 watts, so a generator that can put about 3,600 watts on one 120V leg uses the full service.
What size generator do I need for a 50 amp RV? At least 5,000 watts to run two rooftop ACs, per Dometic. To run two ACs plus a microwave, fridge, and converter, plan for about 7,000 to 8,000 watts.
How many watts does an RV air conditioner use? About 1,800 running and 2,800 starting watts for a 13,500 BTU unit, and 2,000 running and 3,300 starting watts for 15,000 BTU, per Honda.
Will a 3,500 watt generator run an RV air conditioner? Usually, for one 13,500 or 15,000 BTU unit with little else running. That matches Dometic's 3.5 kW minimum. A soft starter adds margin.
How many watts can a 30 amp RV use? Up to 3,600 watts. A 50 amp RV can use up to 12,000 watts.