RV Generator Size Calculator
Calculate exact running watts, starting surge, and continuous amperage for 30 Amp & 50 Amp RVs, soft-start AC units, camper vans, and boondocking setups.
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Surge current reduced by ~65%, saving approximately 1,400 Watts. You can now power rooftop AC on a quiet 2,200W-2,500W inverter generator.
Continuous load (0W) exceeds safety threshold of your 30 Amp service line (2,880W max). Stagger microwave, water heater & AC.
RV Electrical Sizing Guide & Data Tables
Detailed formulas, appliance wattage reference charts, altitude compensation factors, and FAQs.
Calculated Electrical Breakdown Summary
| Parameter | Calculated Value | Unit | Formula Context & Engineering Notes |
|---|
RV Air Conditioner Power Reference
Typical running vs starting surge wattage for standard RV rooftop AC units.
| BTU Rating | Running Watts | Standard Surge | With Soft-Start |
|---|---|---|---|
| 9,000 BTU AC | 1,200 W | 1,800 W | 1,350 W |
| 11,000 BTU AC | 1,200 W | 2,200 W | 1,400 W |
| 13,500 BTU AC | 1,500 W | 2,800 - 3,000 W | 1,700 W |
| 15,000 BTU AC | 1,700 W | 3,300 - 3,500 W | 2,000 W |
Engineering Sizing Formula
Altitude Derating Rule:
Gasoline and propane engines lose roughly 3.5% of power per 1,000 feet of elevation above sea level due to lower oxygen density. At 5,000 ft (Denver), a 3,500W generator will only deliver ~2,880W.
Continuous Load (80% Rule):
National Electrical Code (NEC) recommends running generators at or below 80% of rated capacity for long-term continuous operation to maximize engine life and fuel efficiency.
Frequently Asked Questions
Can a 2,000 Watt generator run a 13,500 BTU RV Air Conditioner?
Without modification, standard 13,500 BTU ACs require 2,800 to 3,000 starting watts, exceeding a 2,000W generator's threshold. However, with a Soft Start Kit (e.g., Micro-Air EasyStart) installed, the starting surge drops below 1,700W, enabling a quiet 2,200W inverter generator to start and run the unit smoothly.
What generator size is required for a 30 Amp RV?
A 30 Amp RV connection carries up to 3,600 watts continuous power at 120V. To utilize full 30A capability, a 3,500W to 4,500W inverter generator equipped with a built-in TT-30R RV plug is ideal.
What size generator is required for a 50 Amp RV?
A 50 Amp RV shore service supports up to 12,000 watts. To run dual 15k BTU air conditioners, microwave, and water heater concurrently, a 5,500W to 7,000W generator (or two 3,500W inverter generators connected in parallel) is recommended.
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