Best Whole House Generators (2026): Standby Sizes Compared

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The best whole house generator is a permanently installed standby unit that starts on its own within moments of an outage, runs on natural gas or propane, and switches your home back to utility power when the grid returns. For Front Range homeowners who lose power in March snowstorms, during wind events or in planned public-safety shutoffs, it is the hands-off answer. It is also a construction project, not an appliance purchase: a concrete or composite pad, a gas line sized for the load, an automatic transfer switch at the electrical panel, permits and inspections. These picks compare the standby sizes on the shelf, plus one large portable alternative, and the guide covers sizing, fuel supply and installation.

Part of our Home Electrical guide — start there for the full picture →

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How we compared: we compared 14 current Amazon listings returned for whole-house generators on what each listing states: rated kW, transfer switch included or not, fuel, monitoring, cold-weather features, weight and warranty. Nine are Generac home standby generators from 10 to 28 kW, two sold without a transfer switch, and five are large portable generators. We did not test, install or run any of these units. Prices, availability and installation costs vary widely, so check the current listing and get installer quotes before buying.

Quick picks: the best whole house generators by home size

Product	Best for	Key features	Price	Buy
Generac 22kW + 200A ATS	Best overall for most homes	22 kW standby with 200A ATS Cold-start and snow-intrusion design 5-year limited warranty	$6,506.10as of Oct 20, 2026 2:23 am GMT+0000	Buy now →Check current price
Generac 14kW + 200A ATS	Mid-size homes, gas furnace	14 kW with 200A ATS ecobee and PWRcell compatible 391 lb	$5,255.10as of Oct 20, 2026 2:23 am GMT+0000	Buy now →Check current price
Generac 10kW + 16-circuit ATS	Essential circuits only	10 kW standby 16-circuit transfer switch Smallest standby here	$3,896.10as of Oct 20, 2026 2:23 am GMT+0000	Buy now →Check current price
Generac Guardian 14kW 7225	Wi-Fi monitoring, proven line	14 kW, under 5% THD stated 200A transfer switch Mobile Link Wi-Fi	$5,499.00as of Oct 19, 2026 9:38 pm GMT+0000	Buy now →Check current price
Generac 24kW + 200A ATS	Large homes with central AC	24 kW with 200A ATS Cellular monitoring 461 lb	$6,875.10as of Oct 20, 2026 5:28 am GMT+0000	Buy now →Check current price
Generac 28kW + ATS + ecobee	Largest standby on the shelf	28 kW with transfer switch ecobee thermostat in title 524 lb	$8,387.10as of Oct 20, 2026 5:28 am GMT+0000	Buy now →Check current price
Westinghouse WGen20000TFc	Portable alternative to standby	20,000 running watts on gas Pairs with WATS200 auto switch CO sensor shutdown	$3,899.00as of Oct 19, 2026 9:38 pm GMT+0000	Buy now →Check current price

Prices are Amazon’s listed prices as of the time shown and change often; check Amazon for today’s price. As an Amazon Associate we earn from qualifying purchases.

The seven picks, compared listing by listing

1. Generac 22kW Home Standby with 200A Transfer Switch — Best Overall Whole House Generator

Best overall

Why we like it

• Includes a 200A automatic transfer switch
• Oil level sensors and improved cold starts
• Sloped roof and rear intake shed snow
• Mid-range size between the 14 and 28 kW options

Generac 7325 — 22 kW standby, 200A ATS included, NG or LP, cellular monitoring, cold-start features, 451 lb, 5-yr

The Size Most Homes Land On, With the Switch Included

Two listings on the shelf are the 22 kW model: this one with a 200 amp automatic transfer switch, and model 7260, sold as the generator alone. Buying the bundle avoids sourcing a compatible switch separately, and a 200 amp switch matches the service size of most newer single-family homes.

All the newer Generac standby listings share the same cold-weather language, and it is relevant here: oil level sensors to confirm readiness, improved cold starts in cold climates and a sloped roof with a rear air intake to reduce ice and snow intrusion. A Front Range unit sits through wind-driven snow and below-zero nights before it is ever asked to run.

What the listing does not say matters too. It gives a single 22 kW figure without separating natural gas and propane output; standby units are often rated lower on natural gas. Remote monitoring requires a Mobile Link premium subscription. And the listing says nothing about installation, which is the larger part of the project.

Check Generac 22kW + 200A ATS price on Amazon

2. Generac 14kW Home Standby with 200A Transfer Switch — Best for Mid-Size Homes

Best for mid-size homes

Why we like it

• 200A switch at a smaller generator size
• Works with ecobee thermostats and PWRcell batteries
• Lighter than the 22 kW by about 60 lb
• Same cold-weather design features

Generac 7323 — 14 kW standby, 200A ATS, NG or LP, ecobee + PWRcell compatible, cellular, 391 lb, 5-yr

The Only Listing That Names Battery and Thermostat Integration

This 14 kW listing is the only one on the shelf that says it works with Generac’s PWRcell battery systems and ecobee by Generac thermostats as part of a home energy system. That matters if you are weighing a generator and a battery together, or want the thermostat to manage loads when the generator is carrying the house. Our guide to the solar generator covers battery-based backup for comparison.

A 14 kW unit is a common choice for homes heated by a gas furnace, where the big electric loads are the furnace blower, refrigerator and a central air conditioner in summer. It is lighter than the larger units, which can simplify pad and placement.

The listing notes that some reviews may refer to the older 14 kW Guardian model, which is worth knowing when reading feedback. Like the 22 kW, it does not split ratings by fuel type.

Check Generac 14kW + 200A ATS price on Amazon

3. Generac 10kW Home Standby with 16-Circuit Transfer Switch — Best for Essential Circuits

Best for essential circuits

Why we like it

• Smallest standby unit on the shelf
• 16-circuit switch targets selected loads
• Same cold-start and snow features
• Lightest standby at 384 lb

Generac G0073210 — 10 kW standby, 16-circuit ATS, NG or LP, cellular, cold-start features, 384 lb, 5-yr

The Only Standby Bundle With a Circuit-Selection Switch

Every other standby bundle on the shelf pairs the generator with a 200 amp whole-panel switch. The 10 kW is the only one that ships with a 16-circuit transfer switch, a sub-panel that moves only the circuits you choose to generator power. That is the honest way to use a smaller generator: furnace, refrigerator, sump pump, some lights and outlets, internet and the garage door, and not the electric range or central air.

For a smaller Front Range home or a buyer who mainly wants the furnace and freezer protected, a circuit-selection setup can cost less to buy and install than a whole-house unit. It also prevents the household from overloading the generator by accident.

The limit is clear. With 10 kW and 16 circuits, this is not whole-house backup in the literal sense. Choose circuits carefully with your electrician.

Check Generac 10kW + 16-circuit ATS price on Amazon

4. Generac Guardian 14kW (7225) — Best for Wi-Fi Monitoring

Best Wi-Fi monitoring

Why we like it

• Wi-Fi monitoring with no subscription mentioned
• Under 5% harmonic distortion stated
• 200A transfer switch included
• Listing recommends a licensed electrician

Generac Guardian 7225 — 14 kW, under 5% THD, 200A switch, Wi-Fi monitoring, 385 lb, 5-yr limited

Wi-Fi Monitoring Instead of Cellular, and a THD Figure

The newer Generac standby listings use built-in cellular monitoring that requires a Mobile Link premium subscription. The Guardian 7225 is the only standby listing that uses Wi-Fi instead, and its listing does not mention a subscription for status and maintenance alerts. Confirm current plan terms with Generac, but for many buyers that difference is worth checking.

It is also the only standby listing that states a power quality figure, under 5 percent harmonic distortion, which matters for furnace control boards, electronics and variable-speed equipment. And it is the only listing that explicitly says Generac recommends installation by a certified and licensed electrician, which is the right expectation for every unit on this list.

The listing does not describe the cold-start or snow-intrusion features the newer models highlight, and Wi-Fi monitoring depends on your router being powered during the outage, which a standby generator usually handles.

Check Generac Guardian 14kW 7225 price on Amazon

5. Generac 24kW Home Standby with 200A Transfer Switch — Best for Large Homes With Central AC

Best for large homes with AC

Why we like it

• Headroom for central AC plus household loads
• 200A automatic transfer switch included
• Same footprint as the 22 kW
• 5-year limited warranty

Generac 7326 — 24 kW standby, 200A ATS, NG or LP, cellular monitoring, 461 lb, 5-yr limited

More Output in the Same Cabinet as the 22 kW

The 22 kW and 24 kW listings share the same stated dimensions, and the 24 kW is just 10 lb heavier. For a larger home with central air, an electric dryer and perhaps a well pump, that extra 2 kW can mean the difference between running the air conditioner during a summer outage and shedding it.

Bigger is not automatically better. A larger generator burns more fuel at the same load and may need a larger gas meter or supply line. Ask your installer for a load calculation rather than picking the biggest unit that fits the budget.

Like the other cellular models, monitoring requires a subscription, and fuel-specific ratings are not stated.

Check Generac 24kW + 200A ATS price on Amazon

6. Generac 28kW Home Standby with Transfer Switch and ecobee — Largest Standby on the Shelf

Largest standby on the shelf

Why we like it

• Highest standby output listed
• Transfer switch included
• ecobee thermostat named in the bundle
• Same cold-climate design features

Generac 7329 — 28 kW standby, ATS included, ecobee in title, cellular, 524 lb, 5-yr limited

The Biggest Standby, but Check the Switch Rating

At 28 kW, this is the largest standby generator among the nine on the shelf. It suits large homes with heavy electric loads: multiple air conditioners, electric heat strips on a heat pump, a large well pump or an EV charger you want kept alive.

Unlike the 14, 22, 24 and 26 kW bundles, this listing’s title does not state the transfer switch amperage, and its bullets do not mention the ecobee thermostat beyond the title. Confirm both before ordering, because a large home that needs 28 kW may also have a 300 or 400 amp service that a 200 amp switch does not match.

At 524 lb, it shares the heaviest standby weight with the 26 kW. Fuel-specific ratings are not stated.

Check Generac 28kW + ATS + ecobee price on Amazon

7. Westinghouse WGen20000TFc — Best Portable Alternative to a Standby Unit

Best portable alternative

Why we like it

• Standby-class output on wheels
• Runs on gas, propane or natural gas
• CO sensor shuts it down
• Pairs with an automatic transfer switch

Westinghouse WGen20000TFc — 20,000/28,000 W, tri-fuel, CO shutdown, under 5% THD, WATS200-ready, 557 lb

The Only Portable on the Shelf Approaching Standby Output

Five large portables turned up in this search, and the WGen20000TFc is by far the most powerful at 20,000 running watts. Paired with Westinghouse’s WATS200 automatic transfer switch and a natural gas connection, it can behave much like a standby system while remaining movable.

The trade-offs are real. At 557 lb it is heavier than any standby unit on the shelf, and “portable” here means wheels and a lift bracket, not something you roll out of a garage alone. As a portable, it must run outdoors well away from the house; the CPSC says at least 20 feet, with exhaust directed away from windows, doors and vents. Its CO sensor shutdown is a meaningful safeguard.

The transfer switch is sold separately, and the listing’s 3-year warranty is shorter than Generac’s 5-year standby coverage.

Check Westinghouse WGen20000TFc price on Amazon

How to size a whole house generator

Standby generators are sized in kilowatts. The right size depends on which loads must run together, not on square footage alone:

• Gas-heated home, no central air: furnace blower, refrigerator, sump pump, lights and outlets. A 10 kW unit with a circuit-selection switch or a 14 kW whole-panel unit often fits.
• Gas-heated home with central air: 14 to 22 kW, depending on AC size and other loads.
• Large or all-electric homes, heat pumps with strip heat, well pumps, EV chargers: 22 to 28 kW, or load management to shed big loads automatically.

Motor starting loads, especially air conditioner compressors and well pumps, can briefly draw far more than their running current. A proper load calculation by your installer accounts for that. None of these listings separates natural gas and propane ratings, and standby generators commonly produce less on natural gas, so ask for the rating on your fuel.

Fuel supply: natural gas meters and propane tanks

Homes with gas service can often run a standby generator from the existing natural gas line, but the meter and piping must supply the generator while the furnace and water heater also run. Large generators may need a meter upgrade from the utility or a larger supply line. Propane homes need a tank sized for multi-day outages and a delivery plan.

The EPA lists generators and back-drafting gas appliances among the sources of indoor carbon monoxide, and warns that CO from a generator run in an enclosed space can linger for hours after it shuts off. The CDC says to make sure gas appliances are vented properly and to have heating systems serviced every year. The CPSC recommends CO alarms with battery backup on every level and outside sleeping areas. A standby generator does not change those basics; it adds another combustion appliance outside the house.

The transfer switch and the electrical code

The automatic transfer switch is what makes a standby system automatic. It senses the outage, starts the generator, disconnects the house from the utility and connects it to the generator, then reverses the process when power returns. That disconnection protects both your equipment and utility workers.

Switches come in two styles on this shelf: whole-panel 200 amp switches on most bundles, and a 16-circuit switch on the 10 kW. Installation falls under the National Electrical Code, which NFPA publishes as NFPA 70, as adopted by your local jurisdiction. For a deeper look at switch types, see our generator transfer switch guide, and for a lower-cost manual setup with a portable, the generator interlock kit guide.

Installation, permits and placement

A standby generator installation typically involves:

1. A site visit and load calculation.
2. Electrical and gas or mechanical permits from your city or county.
3. A level pad and placement that meets the manufacturer’s clearances from windows, doors, vents and combustibles, plus any local setback or noise rules and HOA covenants.
4. Gas piping sized for the generator, and in many cases a utility meter review.
5. Transfer switch installation at or next to the main panel.
6. Inspections, startup and a test under load.

Generac’s own Guardian listing recommends a certified and licensed electrician, and that is the expectation for every unit here. Plan placement with snow in mind: keep the intake and exhaust clear of drifts and roof snow slides, and keep the unit away from where you shovel or plow.

Maintenance and exercise cycles

Standby generators sit idle for months, then must start on the coldest night of the year. They run automatic exercise cycles and need periodic oil, filter and battery service. The newer Generac listings mention oil level sensors and maintenance alerts through the Mobile Link app, which requires a premium subscription on the cellular models. Whatever the monitoring, schedule a yearly service visit, ideally before winter, and keep the unit clear of leaves, snow and vegetation.

Standby vs portable vs battery backup

A standby generator is the most automatic option and the most expensive to install. A large portable, like the Westinghouse above, connected through a transfer switch or interlock, costs less but must be set up and supervised. Battery systems and solar generators make no exhaust and no noise, but store limited energy. Our main guide to the whole-house generator walks through the full comparison.

When to involve an electrician or inspector

Every standby installation needs a licensed electrician and, for natural gas, a qualified gas fitter, with permits and inspections. If you are buying a home with a standby generator already installed, ask for service records and have the transfer switch, gas connection, clearances and battery checked. Our electrical systems hub covers what to ask before major electrical work, and Front Range buyers and homeowners can get in touch through our contact page to connect with a vetted local inspector.

References

• CPSC Warns of Generator Carbon Monoxide and Fire Hazards (2026) — U.S. Consumer Product Safety Commission
• Carbon Monoxide Poisoning Basics — Centers for Disease Control and Prevention
• Carbon Monoxide’s Impact on Indoor Air Quality — U.S. Environmental Protection Agency
• NFPA 70: National Electrical Code — National Fire Protection Association