What Size Generator Do You Need? A Simple Guide to Calculating Power Needs

When the power goes out, a generator can keep your home or business running smoothly, but only if it’s the right size. Too small, and it won’t power everything you need. Too large, and you could end up overspending on something unnecessary. So how do you determine the right generator size? Here’s a simple guide to help you calculate your power needs and choose the best backup power solution.

Step 1: List Your Essential Appliances

Start by identifying the appliances and systems you’ll need to power during an outage. For homes, this could include:

✅ Refrigerator and freezer

✅ Heating and cooling system

✅ Lights and outlets

✅ Well pump (if applicable)

✅ Sump pump (to prevent basement flooding)

✅ Wi-Fi router and essential electronics

For businesses, consider critical equipment like:

✅ Point-of-sale systems

✅ Security systems

✅ HVAC units

✅ Refrigeration (for restaurants, grocery stores, etc.)

✅ Computers and servers

Step 2: Find the Wattage Requirements

Every appliance has a wattage rating, which tells you how much power it needs to run. You can usually find this on the appliance label or in the user manual. If only the amperage is listed, you can use this formula to calculate watts:

Watts = Volts × Amps

Here are some general wattage estimates:

Refrigerator: 600-800W
Sump pump: 1,000-1,500W
Central AC (3-ton unit): 3,500W
Electric water heater: 4,500W
Wi-Fi router: 10-15W

Step 3: Add Up Your Total Power Needs

Once you have the wattage for each essential appliance, add them together to get your total running watts. But don’t stop there—many appliances require extra power when they start up, known as surge watts or starting watts. Make sure to include these in your calculations to avoid overloading your generator.

For example, if your appliances total 6,000 running watts, but your HVAC system requires an extra 2,000 watts to start up, you’ll need a generator that can handle at least 8,000 watts.

Step 4: Choose the Right Generator Type

Now that you know your power needs, here’s how to match them with the right generator:

🔹 Generac Portable Generators:

Wattage Range: Generac's portable generators range from small inverters to models providing up to 17,500 watts, among the largest available.

🔹 Generac Home Standby Generators:

Wattage Range: Generac's Guardian Series home standby generators start at 10,000 watts (10 kW) and go up to 26,000 watts (26 kW).

🔹 Generac Commercial Standby Generators:

Wattage Range: Contact us for available commercial generator solutions!

Need Help Choosing the Right Generator?

Still unsure what size you need? At Goodyear Electric, we specialize in Generac generators and can help you find the perfect fit. Contact us today for a consultation and take the guesswork out of backup power!