Generator Buying Guide

When the power goes out, a generator can keep your house warm in winter or cool in summer; it can keep your food cold, your kitchen cooking, and your computers and phones charged. 

Once upon a time, a generator was a nice tool to have on hand for the occasional outage. But power outages tied to extreme weather are making generators more essential by the day. One estimate from Climate Central, a nonprofit news organization, found that across the U.S., weather-related outages increased by 69 percent in the past decade, based on government and utility company data.  

But while a generator can be a lifesaver, it can be dangerous if you don’t take precautions. People tend to buy generators around major storms. Working by flashlight, in a rush to get the power up and running, they might skip over critical safety steps during setup. Dozens of people die every year from carbon monoxide poisoning related to generators.

We don’t want you—or anyone relying on a generator—to be one of those people. Always use a generator outside, a minimum of 20 feet from your home, with the exhaust directed away from the house. And make sure your house is outfitted with working carbon monoxide alarms outside bedrooms and on every level of your home before you fire up a generator. 

How CR Tests Generators

To test generators for performance, our expert engineers load up each model with a variety of essentials you might want to power during an outage, like a space heater, refrigerator, or window air conditioner. We make sure the generator can handle the load it promises and also determine what happens when a sudden spike in voltage hits, like what would happen if the compressor in your refrigerator kicked on when the generator was already close to capacity. The best models take that in stride, while others bog down or even stall. We also look at how easy it is to move and use a generator, as well as how efficiently it uses gasoline and how long it runs on a single tank.

Consumer Reports runs each generator through a variety of scenarios designed to capture the ways in which a consumer might inadvertently misuse a generator. We conduct these tests in a custom-built vessel on the grounds of our Yonkers, N.Y., test facility. The vessel is wired with calibrated carbon monoxide sensors, and we record CO levels throughout the container when a generator is on, noting how quickly each generator turns off when the levels become potentially dangerous. For more details, read “How Consumer Reports Tests Generators for Safety.”

Know Your Power Priorities

Generators are sold by power output, as measured in watts. The amount of power they deliver determines how many electronics and appliances you can run at once; figure on about 5,000 watts for a typical home. The delivery and quality of power—both of which we test and score in our generator ratings—determines how well they’ll run. A generator with a high output that struggles with power delivery or quality might stall or trip a circuit when it’s bogged down. 

Start by making a list of what you don’t want to go without while the power’s down, then add up wattages to get you in the right ballpark. Here are some rough numbers for common essentials:

Refrigerator: 600 watts
Sump pump: 750 to 1,500 watts
Portable heater: 1,500 watts
Window air conditioner: 1,000 watts
Lights: 5 to 80 watts (per bulb)
Computer: 60 to 300 watts

For a more complete list, check out our report on how to pick the right size generator for your house.

Types of Generators

You can go one of four ways. Home standby generators are installed permanently, can run on natural gas or propane, and kick on automatically during an outage. Portable and inverter generators can be moved around, and they come in different sizes. Some are better for transporting to a tailgate, while others are better kept on your property as a backup power source. And portable power stations are large batteries that store electricity for when you need it, the only option for someone who lives in an apartment, say, and has no way to safely run a generator outdoors.

A standby generator.

Home Standby Generators

• These units cost the most money and should be installed by a pro (so factor in labor costs). An experienced electrician can help with town or municipal permits, noise restrictions, and proper location.

• These start automatically when the power goes out, and typically supply more power than the other four options.

• They run a self-diagnosis and let you know when maintenance is needed. Some even do this via email or text, to you or your dealer.

• You have your choice of fuel—propane, which is less risky to store than the gasoline required for the other models here, or natural gas, which provides an unlimited supply of power. 

• They range from roughly 5,000 to 20,000 watts. 

Typical cost:
$2,000 to $6,000 without installation, which can double these prices.

Home Standby Generators Ratings
A portable generator.

Portable Generators

• These units tend to cost less than home standby generators.

• They typically run on gasoline that you may need to store in large quantities. Stabilizer must be added to your fuel for prolonged storage. 

• You can use portable generators anywhere on or off your property—but never in an enclosed space. These models can quickly produce deadly levels of carbon monoxide. Always run a portable generator at least 20 feet from your home and equipment such as a central air conditioner condenser or a window AC, and direct the exhaust away from your home or any other structure, including the neighbors’ home. 

• If it’s raining, shield your generator with a canopy designed for your particular model.

• Several of these models offer electric starting. The battery required for electric start, however, might not be included.

• Models we test provide 3,000 to 8,500 watts.

Typical cost:
$400 to $2,500.

Portable Generators Ratings
An inverter generator.

Inverter Generators

• Because their engines are more complex, these models generally cost more than traditional portable generators with a comparable output. 

• Inverter generators are much quieter than their conventional counterparts because they throttle up and down to match demand rather than run at full power all the time. They have more sophisticated exhaust systems, which also help tamp down noise.

• They run more efficiently and produce fewer emissions, but you should still follow all the same safety precautions you would with a portable generator. 

• Models we test provide 1,500 to 6,500 watts. 

Typical cost:
$300 to $4,000.

Inverter Generators Ratings
A portable power station.

Portable Power Stations

• These devices don’t use gas or propane—they’re powered by a battery that you can charge by plugging into an electrical outlet or, sometimes, an included solar panel (you might also see them called “solar generators”).

• Portable power stations are relatively new to the market, and they typically cost more than portable gas generators.

• For those concerned about noise, note that these devices are extremely quiet because they have no engine. 

• They don’t produce fuel emissions or carbon monoxide, so you can use them indoors.

• Don’t expect to power as many appliances or run them for an extended period of time, because they don’t provide as much power as portable generators and you can’t keep them running without recharging them, either with electricity or solar power.

• There are no problems with starting because there’s nothing to start—think of these power stations as a large version of a battery pack you might use to charge your cell phone.

• Models we test provide 1,200 to 1,500 watts. 

Typical cost:
$750 to $3,000.

Portable Power Stations Ratings

New Safety Technology for Portable Generators

To reduce the risk of carbon monoxide poisoning, many new generators feature a built-in sensor that triggers an automatic shutoff if CO builds up to dangerous levels in an enclosed space; some also have engines that emit less CO in the first place. Recent test data from CR shows that this safety feature is likely to save lives.

Consumer Reports recommends a portable generator only if it passes our newly expanded CO safety technology test.

Even if your generator has this potentially lifesaving feature, we still advise consumers to follow our longstanding safety guidelines: Always operate a generator a minimum of 20 feet from your home, with the exhaust directed away from any windows, doors, air conditioners, and other structures. 

Features to Consider

Don’t let rain, snow, or wind keep you in the dark. Consider these options to make sure you get the best generator for your needs.

Automatic CO Shutoff
This critical safety feature automatically shuts down a generator’s engine if a built-in CO sensor detects levels of the deadly gas building up to certain levels. A portable generator must have this feature, and must pass CR’s safety tests, to earn a spot on our list of CR recommended generators. More brands than ever offer models with this technology, including heavyweights such as Generac, Honda, and Ryobi. In fact, we have over a dozen generators in our ratings with a CO safety shutoff. You might see marketing terms such as “CO Guard,” “CO Protect,” “CO Detect,” “CO Shield,” or “CO Sense.” The way to verify whether a generator meets one of the two standards is to look for one of these certifications on the packaging:

• ANSI/UL2201 Certified for Carbon Monoxide Safety
• ANSI/PGMA G300 Certified Safety & Performance

Low-CO Engine
An additional safety feature that brands such as Ryobi and Echo are using to guard against risk of carbon monoxide poisoning.

Automatic Start
When the power goes off, the generator goes on—without you lifting a finger. This is great if you travel a lot or work far from home, and can’t always get there quickly in an emergency.

Electric Start
Several portable models offer this push-button alternative to the hassle of pull-starting the engine. Just factor in the added cost (around $50) if the battery is not included. Stationary models have automatic starting.

Alternative Fuel Capacity
Most portable models run only on gasoline, though some come equipped to run on a propane tank or natural-gas line and others can be converted with kits.

Fuel Gauge
Especially during long blackouts, you may appreciate the ability to see at a glance how much fuel remains in your portable generator.

Low-Oil Shutoff
If oil falls below minimum levels, the generator shuts down to prevent engine damage. Typically a standard feature on stationary generators, it’s increasingly common on portables.

Multiple Outlets
Four or more let you best use the wattage by spreading the load, though we recommend using these only in an extreme pinch at home, or for when you’re away—at, say, a campsite. See the next section on transfer switches.

Removable Console
This connects to the generator so that you can plug in appliances without running (potentially risky) extension cords outdoors.

Yes, You Need a Transfer Switch

What’s that? The short answer: It safely connects a home standby or portable generator to your circuit panel via one cable. Skipping it means you’ll need to use extension cords, which can be dangerous—it’s easy to overload an extension cord, which can cause it to overheat and start a fire. 

And a transfer switch is infinitely more convenient. With a transfer switch, you can power entire circuits in your home with no extension cords. That means essentials without a plug, such as overhead lights, well pumps, and water heaters, can be used freely—if you rely on extension cords, you can power only items with a plug, and even then, you’ll need to connect them to your generator with heavy-duty outdoor-rated extension cords. 

We recommend that you have a licensed electrician install a transfer switch, and you should be prepared to pay from $500 to $900 with labor. With a stationary model, the transfer switch turns on automatically. For portable models, you’ll need to flip a few switches by hand when the power goes out. (Be sure to have your electrician walk you through the procedure.) 

Most transfer switches are designed for a 220-volt input, which means you’re looking at a generator of 5,000 watts or more. For stationary models, it shuts off when the power goes on; for a portable, you’ll flip the same switches the other way to bring back live power.

Keep in mind that you’ll need to choose which circuits are connected to the transfer switch. One tip that will make prioritizing easier is to determine which outlets and appliances are controlled by each circuit breaker in your panel, and label them accordingly. The easiest way: Get a small electric device called a digital circuit breaker finder, which you can buy for less than $50. That way, you can make sure the electrician connects the circuits for all your essentials. 

Want to save money? Install an interlock device instead, which costs $100 to $200 less than a transfer switch and can be installed in less time by an electrician. This device allows your generator to power your home’s entire circuit breaker panel, but it also prevents running the generator while you’re getting power from your utility company once your electric service is restored. That’s important because operating a generator while you’re also getting power from your utility company could fry your electronics, and potentially shock a utility worker working near your home. 

A portable generator hooked up to an electrical panel via a transfer switch.
Illustration: Chris Philpot

Generator Brands

Briggs & Stratton makes portable, inverter, and home standby generators. In addition to manufacturing products sold under the Briggs & Stratton brand name, it makes gasoline engines used by other generator brands.
Cat is a smaller manufacturer of gasoline-powered portable generators. It primarily focuses on the construction market, with generators designed for worksites.
Champion is a smaller manufacturer of all kinds of generators, ranging from small inverter models that run on gas, all the way up to large standby generators that can power an entire house using propane or natural gas.
DeWalt is best known as a tool brand, but it makes gas-powered portable generators with contractors in mind. Its products are sold primarily at Home Depot.
Echo is a smaller outdoor power equipment company that’s new to the generator market. Most of its models are recreational or midsized; many of them have low-carbon-monoxide engines.
Generac is the largest generator manufacturer in the U.S. It makes everything from small recreational generators up to home standby generators, and its products are widely available, including at Home Depot, as well as through smaller dealers.
Honda has a reputation for making stellar generators, particularly inverter models. Honda sells generators through small dealerships and not at home centers.
Ryobi is a Home Depot-exclusive tool brand that makes low-CO generators. It made the first low-CO generator on the market, and it offers recreational, inverter, and portable models.

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