Contents
- 1 Why Does Generator Size Matter?
- 2 Running Watts vs Starting Watts: What is the Difference?
- 3 How to Use the RV Generator Size Calculator
- 4 The Math Behind Generator Sizing
- 5 RV Generator Size Calculator
- 6 What Each Generator Size Can Handle
- 7 Smart Tips for Picking Your RV Generator
- 8 Mistakes People Make When Sizing a Generator
- 9 Common Questions About RV Generator Sizing
- 10 More Resources
- 11 Get Started Now
So you want to hit the road in your RV, but you have no idea what size generator to buy. That is a common problem. The good news? Our RV Generator Size Calculator below does the math for you in seconds.
A generator that is too small will not power your air conditioner or microwave. One that is too big wastes gas and money. This guide breaks down everything you need to know. We will show you how to figure out your power needs and pick the right generator for your camper, travel trailer, or motorhome.
Why Does Generator Size Matter?
The right size generator keeps you comfortable and safe on the road. Here is why it matters:
Protect Your Stuff
A small generator causes power drops. Those drops can fry your TV, air conditioner, or CPAP machine. The right size keeps your gear safe.
Save on Gas
A huge generator running at low power is a gas hog. The right size runs at the sweet spot. You spend less at the pump.
Make It Last
Generators that run at full blast all the time wear out fast. A well-sized unit runs easier and lasts years longer.
No More Worries
You will know your generator can handle the AC on a hot day. That peace of mind is worth a lot.
Running Watts vs Starting Watts: What is the Difference?
Before you use the RV generator calculator, you need to know about two types of wattage:
Running Watts
This is the steady power an appliance needs to keep working. Your fridge uses this amount all day long. Most labels show this number.
Starting Watts
This is the extra juice needed to start a motor. It only lasts a few seconds. But it can be two or three times higher than running watts.
How to Use the RV Generator Size Calculator
Our free generator wattage calculator is simple to use. Here is how it works:
Pick Your Appliances
Scroll through over 100 RV appliances. We have air conditioners, fridges, microwaves, TVs, and more. Each one has the correct wattage built in.
Add Custom Items
Got something special? Pick "Custom Appliance" and type in the wattage yourself. Check the label on your gear to find the numbers.
Set the Quantity
Have two fans or five lights? Change the quantity so the calculator adds them all up.
See Your Results
The calculator shows your total running watts, peak starting watts, and the best generator size. It even compares popular models so you can shop smart.
The Math Behind Generator Sizing
Want to know how we figure it out? Here is the formula:
Best Generator Size = (Higher of Running or Starting Watts) x 1.25
Step 1: Add up the running watts for all the stuff you want to use at the same time.
Step 2: Find which appliance has the biggest starting surge.
Step 3: Compare your running total to your peak starting watts. Use whichever is bigger.
Step 4: Multiply by 1.25. That extra 25% gives you room to grow and keeps the generator from straining.
Real World Example
Let us say you want to run these items in your RV at the same time:
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| 13,500 BTU Air Conditioner | 1,500W | 4,500W |
| RV Refrigerator | 400W | 1,200W |
| Microwave (1000W) | 1,000W | 1,500W |
| LED Lights (10 bulbs) | 100W | 100W |
| Total | 3,000W | Peak: 4,500W |
The Math: 4,500W is bigger than 3,000W. So we use 4,500W x 1.25 = 5,625W needed
A generator between 5,500 and 6,000 watts would be perfect for this setup.
RV Generator Size Calculator
Calculate your power needs and find the perfect generator for your RV
What Each Generator Size Can Handle
After you use the RV generator size calculator above, you will see different size ranges. Here is what each one can do:
Can handle: Phone chargers, LED lights, small fans, laptops, and a 12V fridge
Cannot handle: Air conditioners, microwaves, or hair dryers
Best for: Tent camping, small pop-up campers, or folks who only need the basics
Can handle: One small AC, fridge, TV, and a few kitchen gadgets one at a time
Cannot handle: Multiple power-hungry items at once
Best for: Small travel trailers, teardrop campers, or weekend trips
Can handle: 13,500 BTU AC, microwave, fridge, TV, and lights all at once
Most popular: This is the sweet spot for most RV campers
Best for: Mid-size travel trailers, Class C motorhomes, or full-time RV living
Can handle: Two AC units, electric water heater, and everything else running at full blast
Also good for: Job sites or home backup power during outages
Best for: Big Class A motorhomes, fifth wheels, and luxury RVs
Smart Tips for Picking Your RV Generator
Go With an Inverter Generator
Inverter generators make clean, steady power. They run quiet. They are safe for laptops, TVs, and medical gear. Honda EU series and Champion are two popular brands.
Watch the Noise Level
Most campgrounds have rules about noise. They usually cap it at 60-65 decibels. Look for a generator under 60 dB so you stay friendly with your neighbors.
Think About Gas Mileage
A 3,500-watt generator burns about half a gallon to one gallon per hour at half load. Dual-fuel models can run on propane too. That is handy for long trips off the grid.
Buy a Little Bigger
The 25% buffer in our formula leaves room for growth. Maybe you add a second AC later. Maybe you get a bigger fridge. A little extra power now saves headaches later.
Mistakes People Make When Sizing a Generator
Only Counting Running Watts
Many RV owners add up running watts and call it a day. Then their generator trips when the AC kicks on. Motors need a big surge to start. Our generator sizing tool counts that surge for you.
Buying Small to Save a Few Bucks
A cheap, undersized generator runs at max power all the time. It wears out fast. It guzzles gas. It might damage your appliances. You end up paying more in the long run.
Not Thinking About Altitude
Generators lose about 3.5% of their power for every 1,000 feet of elevation. Camp in the mountains? Size up a bit. Our calculator gives you headroom for higher ground.
Skipping Parallel-Capable Models
Some smaller generators can link together for double the power. Use one for light days. Hook up two for heavy loads. That gives you flexibility without buying a monster unit.
Common Questions About RV Generator Sizing
What size generator do I need for my RV air conditioner?
A typical 13,500 BTU RV air conditioner needs at least 3,000 watts. The AC draws about 1,500 running watts, but the startup surge hits around 4,500 watts. A 15,000 BTU unit needs 3,500 to 4,000 watts. Use the RV generator calculator above to add your other appliances and get an exact number. We suggest a 3,500-watt inverter generator at minimum for reliable AC use.
Can I run two air conditioners on a portable generator?
Yes, but you need serious power. Two AC units usually need 5,500 to 7,000 watts. Look for a generator with at least 6,500 to 7,500 starting watts. A soft-start kit can cut the startup surge by up to 70%. That lets a smaller generator handle both units. Add your specific ACs to the calculator above to see your exact needs.
What is the difference between running watts and starting watts?
Running watts is the steady power an appliance uses after it starts. Starting watts is the burst of power it needs to turn on. Things with motors, like ACs, fridges, and power tools, have much higher starting watts. The surge only lasts a second or two. Our generator wattage calculator handles both numbers so you get the right size.
How do I find the wattage of my RV appliances?
Check the label on the back or bottom of the appliance. It should show watts, amps, or volt-amps. No watts listed? Multiply amps by volts. Most RV outlets are 120 volts. So a 12-amp air conditioner uses about 1,440 running watts (12 x 120 = 1,440). Our calculator has over 100 common appliances with the wattage already filled in.
Is a 2,000-watt generator enough for an RV?
A 2,000-watt generator works for basic stuff. It can power lights, charge phones, run a laptop, and keep a small 12V fridge cold. It cannot run most RV air conditioners. Even small AC units need at least 1,500 running watts plus a big startup surge. Want to run your AC? Go with at least 3,000 to 3,500 watts. Use the RV generator size calculator above to test your setup.
What is the best generator brand for RV use?
Top brands include Honda (the EU2200i and EU3000iS are super quiet and reliable), Champion (great price and solid warranty), Westinghouse (lots of features for the money), and Yamaha (quality on par with Honda). Look for an inverter generator under 60 dB for campground use. Our comparison table above shows specs and prices for popular models.
How long will an RV generator run on a tank of gas?
It depends on the tank size and how hard you push it. A typical 3,500-watt generator with a 4-gallon tank runs about 8 to 12 hours at half load. At full load, expect 4 to 6 hours. Inverter generators adjust engine speed to match the load. That saves gas when you are not using much power. Dual-fuel models can also run on propane for longer trips.
Do I need a special generator for my RV electronics?
Yes, inverter generators are the way to go. They put out clean, stable power with less than 3% harmonic distortion. That is safe for laptops, smart TVs, CPAP machines, and game consoles. Old-school conventional generators can spike and dip. Those surges can fry sensitive gear over time. Every generator in our comparison table is an inverter model.
More Resources
For more information on portable generator safety, check out the U.S. Consumer Product Safety Commission generator safety page. It covers carbon monoxide dangers, where to place your generator, and how to avoid electrical hazards.
Get Started Now
Picking the right generator does not have to be hard. Our RV Generator Size Calculator does the heavy lifting. It tracks running watts, starting watts, and adds a safety buffer. It even shows you how popular models stack up against your needs.
Whether you take weekend trips or live on the road full time, the right power setup makes all the difference. Use the calculator above to plug in your appliances. See your results in seconds. Then pick a generator that fits your RV lifestyle.
Have questions about your results? Drop us a line. We are happy to help you find the right fit.
