Generator Cost: Complete Guide to Portable, Partial, and Whole-House Pricing

A whole-house generator costs around $5,000 on average, with a typical range of $1,500 to $9,000. The generator's capacity, measured in kW, is the single biggest driver, since a system built to power your whole home costs far more than one built to cover just the essentials during an outage.

When you request a quote through Serve Kei, a vetted local electrician calculates the actual electrical load for your home instead of guessing at a size.

Cost by Generator Type and Size

Standby generators (partial and whole-house) are permanent installations, hardwired into your electrical system with an automatic transfer switch, so they kick in during an outage without you having to do anything. Portable generators are cheaper but need to be manually connected and fueled each time.

Sizing: How Much Power Do You Actually Need?

Sizing comes down to adding up the wattage of what you want to keep running:

As a rough guide, 8,000 watts covers most essential appliances plus things like a sump pump, well pump, or dishwasher. To make it feel like the power never went out at all, most homes need 20,000 watts (20 kW) or more, which is why whole-house systems start around 22 kW. A 2,500 square foot home typically needs a 20 to 25 kW generator, though your electrician should confirm with an actual load calculation rather than square footage alone.

What Affects the Cost

Capacity. This is the main lever, as the table above shows. Going from a 9 kW partial system to a 22 kW+ whole-house system roughly doubles or triples the equipment cost before installation is even factored in.

Fuel type. Natural gas is the most common fuel for standby generators and generally the most cost-effective to run long-term. Propane and diesel are alternatives where natural gas isn't available, with different running costs and tank requirements.

Installation complexity. A transfer switch, gas line work, and a concrete pad are typically part of a standby install. If your electrical panel needs upgrading or the gas line has to run a long distance, labor cost goes up accordingly.

Brand. Generac is the dominant brand in home standby generators, by far the most-searched name in this category, and accounts for the large majority of the whole-house standby market. Because of that market share, the whole-house tier in the table above (22 to 48 kW, $5,000 to $18,000) already substantially reflects typical Generac pricing rather than sitting apart from it. Branded, dealer-installed systems tend to price toward the middle-to-upper end of that range, reflecting the manufacturer's own installation and service network rather than a fundamentally different product.

Permits and inspection. Standby generator installation typically requires an electrical permit and sometimes a gas permit, both usually handled by your installer.

Portable vs. Standby: Which Do You Need?

A portable generator is the lower-cost option for occasional short outages, camping, or as a backup for a few key items. A standby (partial or whole-house) system makes more sense if you:

Getting an Accurate Quote

Have ready: your home's square footage, which appliances and systems you want covered during an outage (fridge, HVAC, sump pump, medical equipment), your preferred fuel type if you have one, and whether you already have a suitable spot for outdoor placement.

Frequently Asked Questions

How much does a whole-house generator cost installed?

Around $5,000 on average, with a typical range of $1,500 to $9,000. Larger-capacity systems (30 kW and up) can run toward $18,000.

What size generator do I need for my house?

Add up the wattage of what you want to power. 8,000 watts covers essentials; 20,000 watts (20 kW) or more covers a full home. A 2,500 sq ft home typically needs 20 to 25 kW, confirmed by a load calculation.

Is a Generac generator more expensive than other brands?

Generac is the dominant standby generator brand and accounts for most of the whole-house market, so the whole-house pricing tier above ($5,000 to $18,000 for 22 to 48 kW) already reflects what most Generac systems cost. Branded dealer installs tend to price toward the middle-to-upper end of that range, reflecting the brand's own equipment and service network rather than a fundamentally different product.

Is a Patriot generator the same thing as a whole-house standby generator?

No, and this trips up a lot of searches. "Patriot Power Generator" is a portable solar battery power station sold directly by 4Patriots, priced roughly $1,500 to $3,000, not a hardwired standby system. It's a plug-and-go retail product for keeping a few essentials running, not a whole-home installation. If you're comparing it to the systems in this guide, you're comparing two different categories of backup power, not two brands of the same thing.

How long does generator installation take?

A standby generator install, including the transfer switch, gas line, and pad, typically takes 1 to 2 days, longer if electrical panel upgrades are needed.

What fuel type is best?

Natural gas is the most common and generally most cost-effective for standby systems where it's available. Propane is the usual alternative.

Do I need a permit to install a generator?

Yes, standby generator installation typically requires an electrical permit and often a gas permit, both normally handled by your installer.

Bottom Line

Most homeowners land around $5,000 for a whole-house generator installed, but capacity is what moves that number most, from under $2,000 for a portable unit to $18,000 for a large-capacity whole-house system. Start with a real load calculation rather than guessing at size, since an undersized generator won't cover what you actually need during an outage.

Related reading

National averages are useful for planning. Verify pricing against a quote for your home before treating any range as final.