What Size Generator Do You Need for a 30 Amp RV?
By the Generator Size Calculator Team · Updated · 6 min read
Quick answer: A 30 amp RV runs on 120 volts, so its service tops out at 30 × 120 = 3,600 watts. Cummins says a 3,600-watt generator matches shore power, a 4,000-watt generator adds motor-starting margin, and 2,500 to 2,800 watts is often a good minimum when you run an air conditioner and keep the other loads modest. Adding the loads up before a trip matters more than the label on the generator.
The 3,600-watt limit
Watts equal volts times amps. A 30 amp RV connection at 120 volts is 30 × 120 = 3,600 watts, and that is the most the RV can pull from shore power or a generator. Cummins uses the same math. A generator bigger than 3,600 watts cannot push more through a 30 amp connection, though extra rating still gives you headroom for starting motors.
For a continuous load, a common rule is to stay under 80% of a limit, which here is about 2,880 watts. See the generator amps calculator to convert between watts and amps.
Which generator size to choose
| Generator | What Cummins says |
|---|---|
| 2,500 to 2,800 W | Often a good minimum for a 30 amp RV with air conditioning |
| 3,600 W | Matches the 30 amp shore power limit |
| 4,000 W | Adds power for starting motors such as the air conditioner |
An air conditioner uses 1,200 to 2,400 running watts and can draw up to three times that for the first few seconds, so the start-up is what pushes you toward 3,600 to 4,000 watts. Read what size generator runs an RV air conditioner. An inverter model is quieter at a campsite. See inverter vs conventional generators.
A load budget on 30 amp service
| Load | Running watts | Cummins range |
|---|---|---|
| One air conditioner (13,500 to 15,000 BTU) | 1,800 | 1,200 to 2,400 |
| Refrigerator | 500 | 400 to 1,000 |
| TV | 150 | 43 to 600 |
| Microwave | 1,000 | 750 to 1,500 |
| All four together | 3,450 |
The watt values in the middle column are assumed examples that sit inside Cummins' ranges. With the microwave on too, the total of about 3,450 watts is right at the 3,600-watt limit and well over the 2,880-watt comfort mark. Without the microwave the total is about 2,450 watts, so the usual habit is to turn the air conditioner off, or wait, while the microwave runs.
Add your air conditioner, fridge and the rest.
Tips for camping
- Run the biggest loads one at a time. The air conditioner, microwave and any heater should not all run together.
- Check the RV's own breaker panel. The 30 amp main breaker trips before the generator is hurt.
- Consider two small inverters. See the parallel generator calculator.
- Check campground quiet hours and rules before you run any generator.
Run the generator outdoors, well away from the RV's doors, windows and vents. Carbon monoxide can build up inside a camper even with a window open. See how far a generator should be from a building.
Frequently asked questions
How many watts is a 30 amp RV?
At 120 volts, 30 amps is 3,600 watts. That is the most a 30 amp RV connection can supply.
Can a 3000-watt generator run a 30 amp RV?
Yes, with care. You get about 2,400 watts at the 80% mark, so run one air conditioner and a few small loads and avoid the microwave at the same time. Cummins gives 2,500 to 2,800 watts as a common minimum.
Do I need a 3600 watt generator for a 30 amp RV?
Not always. A 3,600-watt unit matches shore power, but many people run fine on 2,500 to 3,500 watts by managing loads.
Is a 4000 watt generator too big for a 30 amp RV?
No. The RV can only draw 3,600 watts, but the extra rating helps with the air conditioner start-up.
Can I run a 30 amp RV on a 2000 watt generator?
Only a light setup, such as a fridge, lights and small electronics, or an air conditioner with a soft starter. A normal air conditioner start-up is hard on a 2,000-watt unit.
Related calculators
Sources: Cummins, What size generator do I need to power an RV? (30 amp and 120-volt math, 3,600 and 4,000-watt generators, 2,500 to 2,800-watt minimum, appliance ranges); Cummins, RV generator electricity basics (air conditioner running watts and start-up). The 80% comfort mark is a common rule of thumb. The watt values in the load budget are assumed examples within Cummins' ranges.