Use this calculator to estimate how many watts your portable generator needs based on the appliances you plan to run.
Select your appliances below to get an instant recommendation.
Generator Size Calculator
Estimate your generator size based on real appliances, including running watts and startup surge — not guesswork.
Select the appliances you plan to run at the same time, or add your own custom appliances to calculate the generator size you actually need.
Select Your Appliances
Choose the appliances you expect to run simultaneously.
Running watts are added together, while only the largest startup surge is applied.
Kitchen
Heating & Cooling
Home Office & Entertainment
Laundry & Cleaning
Tools & Workshop
Add Custom Appliances (Advanced)
If your appliance is not listed, you can add it here.
- Running watts: the power required during normal operation
- Starting watts: the brief surge required when the appliance starts
How this size is calculated: We total all running watts, then account for the additional startup surge from the largest appliance, rather than adding all starting watts together.
What to look for when buying:
Choose a generator rated at or above this wattage for
continuous output.
Note: This estimate assumes you won’t operate multiple high-wattage heating appliances (such as space heaters, electric dryers, or stoves) at the same time.
What Generator Size Should You Actually Buy?
Generators are sold in standard size ranges, not exact watt numbers. Use your calculated result to choose the next practical size up.
| Your Calculated Need | Common Generator Size |
|---|---|
| Up to 1,000 W | 1,000–1,500 W |
| 1000 to 2,000 W | 2,000–2,500 W |
| 2,000–3,000 W | 3,000–3,500 W |
| 3,000–4,000 W | 4,000–4,500 W |
| 4,000–5,000 W | 5,000–5,500 W |
| 5,000–6,500 W | 7,000–7,500 W |
| 6,500–8,000 W | 8,000–9,000 W |
Your power requirement exceeds common portable generator sizes. Consider larger models or standby solutions.
What to Look for When Buying
- Continuous (running) watts at or above your recommended size
- Surge watts high enough to handle startup loads
- Noise level under 70 dB for home or apartment use
- CO automatic shutoff for safety
Ready to narrow down your options?
Explore generators in the size range that matches your calculation.
View Suitable Generator Sizes → Read our generator buying guideQuick Questions
Why does the recommended generator size seem larger than expected?
Do I need to include every appliance I own?
Is a 6500 watt generator enough to run a house or essential appliances?
In most cases, yes — a 6500 watt generator is enough to run essential household appliances, but it is not designed to power a full electric home.
A 6500W generator can typically handle a refrigerator, sump pump, furnace blower, lights, internet equipment, and one air conditioner. It may struggle if central AC, electric dryers, ovens, or multiple high-surge appliances are running at the same time.
Use the calculator above to check your exact running load and starting surge.