Introduction
Choosing the correct generator size is the most important decision when buying an inverter generator. Too small and your appliances will not start. Too large and you overspend on wattage you never use. This guide offers a practical framework to answer the question: What size inverter generator do I need? For a deeper technical overview of inverter design and performance, see the main Inverter Generator Guide.
How to Calculate the Size You Need
To determine the correct wattage:
- List all the appliances you want to run.
- Identify starting watts vs running watts.
- Add the highest starting load to your continuous loads.
- Choose a generator with 20–30% extra headroom.
This method provides stable operation, reduces nuisance overloads, and protects sensitive devices. For help translating load into runtime expectations, see Inverter Generator Runtime.
Common Appliance Wattage Requirements
Here are typical wattage estimates for common appliances:
| Appliance | Starting Watts | Running Watts |
|---|---|---|
| RV AC (13,500 BTU) | 1,600–2,200 | 1,100–1,500 |
| Refrigerator | 600–800 | 150–300 |
| Microwave | 1,000–1,500 | 1,000–1,500 |
| Coffee Maker | 800–1,000 | 600–900 |
| Laptop | 0 | 50–100 |
| TV | 0 | 80–150 |
| CPAP Machine | 0 | 30–60 |
Your required size depends heavily on the largest appliance on the list—often an air conditioner or microwave with high starting watts.
Recommended Generator Size for Different Uses
1. Camping (Lights + Phones + Fridge)
Recommended size: 2000–2400W
Best for:
- charging phones, tablets, and cameras
- running LED lights
- powering a portable fridge
- quiet overnight operation
These compact units are the most portable and fuel-efficient. For camping-specific fuel savings, see Inverter Generator Fuel Consumption.
2. RV Travel (Air Conditioner + Essentials)
Recommended size: 3500–4500W
Enough to power:
- RV air conditioner
- refrigerator
- microwave
- TV and outlets
This is the most popular wattage range for travel trailers and motorhomes because it balances startup surge capacity with manageable size and noise.
3. Home Backup (Refrigerator + Lights + Wi-Fi)
Recommended size: 4000–6500W
Supports:
- refrigerator and freezer
- essential lighting
- microwave or coffee maker
- modem/router and work devices
- selected small appliances
Larger homes or users running multiple major appliances should move toward or above 6000W.
4. Power Tools / Job Site Use
Recommended size: 5000–7000W
Depending on tools, this range can support:
- saws
- air compressors
- grinders
- simultaneous operation of several power tools
Higher wattage ensures safe startup surges and smoother operation for inductive loads.
Do You Need Extra Headroom?
Yes. Add 20–30% extra wattage above your calculated load to avoid:
- overloads and tripped protection
- voltage drops under surge
- shortened generator lifespan
A generator running at roughly 70–80% of its rated capacity will last longer and hold voltage more consistently than one operating at the limit.
Parallel Capability as an Alternative
If you are unsure which size to buy initially, parallel capability offers a flexible path:
- start with a 2000–2400W unit
- add a second inverter generator later using a parallel kit
- achieve 4000–4500W combined output when needed
This “upgrade later” strategy is very popular with RV travelers who value portability but occasionally need extra power. For more detail on how this works, see Parallel Inverter Generator.
Conclusion
The size of inverter generator you need depends on your appliance list, starting watt requirements, and use case. Most campers are well served by 2000–2400W, RV owners typically choose 3500–4500W, and homeowners often prefer 4000–6500W. By accurately estimating your load and adding appropriate headroom, you can select a generator that runs safely, quietly, and efficiently.
For additional buying advice, load-planning tips, and runtime examples, explore the complete Inverter Generator Guide and related articles in the inverter generator blog cluster.