Generator Buying Guide
A Generator Won't Leave You in the Dark

When the power goes out, a generator can keep your house warm (or cool), your kitchen cooking, and your computers and phones charging.

Sales spike around major storms—just before and a few weeks after—which means that too many buyers shop when the power’s out, randomly choosing a generator that looks up to the task, and then have no idea what to do with it when they get it home. (And, often, all this is done by flashlight, no less.)

Buying in haste may also mean bypassing recommended installation procedures and relying on extension cords, which we don't recommend. Read our expert tips on how to power up.

Know Your Power Priorities

Generators are typically sold by wattage. How much they put out determines not only how many lights and appliances you can run at once, but also how well. Figure on about 5,000 watts to cover the basics.

• List what matters to you. Some common essentials are the refrigerator (about 600 watts), sump pump (750 to 1,500 watts), portable heaters (1,500 watts), window air conditioner (1,000 watts), lights (60 to 600 watts), and computers (60 to 300 watts). Reliability matters, too. We checked which models faltered when demand was high and which ones overheated appliances.

• Map the outlets and switches in your house to know which circuit on the service panel powers what. The easiest way: two people with cell phones flipping switches. An electrician can do this for a fee.

Pick an Option

You can go two ways: A stationary or standby model installed onsite, or a portable generator.  

Picrture of a stationary generator

Stationary Generators

• These units cost more 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 often supply more power.

• 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—natural gas or propane, both of which are less risky to store than gasoline.

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

• They cost from $5,000 to $10,000.

Picture of a portable generator.

Portable Generators

• These units tend to cost less.

• They run on gas or propane that you may need to store in large quantities. Stabilizer must be added to store gasoline safely.

• You can use them anywhere on or off your property, but they must be at least 15 feet away from your house, doors, or windows—and not in an enclosed space. If it's raining, you must use a tent or cover.

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

• They provide from 3,000 to 8,500 watts.

• They cost from $400 to $1,000.

Features That Count

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 Start
When the power goes off, the stationary generator goes on—without your intervention. This is great if you travel a lot or have a long commute.

Electric Start
Several portables 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—or can be converted with kits.

Believe it or not, some portables price these separately. You could probably move a wheeled generator solo, but without wheels, you'd need help. (All the ones we've tested weigh upwards of 200 pounds.) Wheels can cost up to $150 extra.

Fuel Gauge
Check fuel level at a glance on a portable; this is especially useful during long blackouts.

Low-Oil Shutoff
If oil falls below minimum levels, the generator shuts down to prevent damage. This is usually standard on stationary generators, but it's increasingly common on portables, too.

Inverter Technology
On some higher-end portables; this provides cleaner power that won't overheat sensitive electronics. Some campsites require it because inverter generators typically run much more quietly.

Multiple Outlets
Four or more lets you best use the wattage by spreading the load, though we recommend using these only for emergency use—or for away uses such as camping. See the next section on transfer switches.

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

Guess What: You Need a Transfer Switch

What's that, you say? Well, the short answer is that it links the stationary or portable generator to your circuit panel in one cable. Skipping it could cause appliances to fry, endanger utility workers, and damage the generator.

We recommend that you have a pro install it, and it could cost from $500 to $900, with labor. With a stationary model, the transfer switch turns on automatically. For portables, you connect it and then flip a few switches by hand. It works with 5,000 watt or higher models. For stationary models, it shuts off when the power goes on; for a portable, you flip the same switches back to live power.

Want to save money? Install an interlock device ($50 to $150) instead. This covers your service panel's main cutoff switch—so when the power pops back on, you can't accidentally put the generator on, too (which would be a bad thing). You have to follow a certain sequence to avoid getting an energy spike, hence the budget price.

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

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