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Home Generator Buying Guide – How to Choose the Best for Your Needs

A power outage is a nuisance at best. It affects everything you need to work and have fun at home, such as your lights, TV, and computer. At worst, a blackout can pose an actual danger to life and limb. It can knock out your heating system in the freezing cold of winter, kill your air conditioner during a summer heat wave, or interfere with lifesaving medical equipment.

If you can’t afford to lose power for even a few hours — or if you just don’t want to deal with the hassle of frequent blackouts — a backup power generator can be the ideal solution. It provides emergency power for your home so you can keep all your vital systems online.

How to Choose a Backup Power Generator

Simply deciding to buy an emergency backup generator is only the first step. The tricky part is finding the right one for your needs. First, you have to decide which type of generator to buy. You also need to consider important details like what fuel source to use, what size you need, and which features are essential to you.

Portable Generators vs. Standby Generators

The first decision to make is whether you need a small portable generator or a larger home standby generator.

Portable power generators, which are usually mounted on wheels, have to be pushed outside and hooked up to your home’s electrical system when a blackout starts. Standby generators are permanently installed outside your home and start automatically when the power to your home goes out.

Each type has its advantages and disadvantages. Portable generators are smaller and cheaper, and they don’t require professional installation. However, standby generators are a lot easier to use, making them a better choice for dealing with frequent power outages.

To choose the right type for you, ask yourself a few questions:

  • How Do You Want to Use It? A portable generator is just that — portable. You can use it to power your home in an emergency, but you can also take it with you for camping trips or tailgate parties. That gives it more flexibility than a stationary generator, which is permanently attached to your house.
  • How Much Power Do You Need? Standby generators crank out a lot more power than portable ones. They can produce anywhere from 5,000 to 20,000 watts — enough to power every system in your home. By contrast, portable generators can typically put out only between 3,000 and 8,000 watts. That’s enough to run a few critical systems, such as a fridge and some lights plus a window AC unit or the fan for a gas furnace. However, they can’t keep your whole house running along as usual.
  • What’s Your Budget? Portable generators are the cheaper option. According to the generator buying guide from Consumer Reports, most models cost between $400 and $1,000. You can install this type of generator yourself or pay a few hundred dollars to an electrician to put in a transfer switch, which makes it safer and easier to use. Consumer Reports puts a standby generator’s price at $3,000 to $6,000, plus the cost of professional installation. All told, you could end up paying anywhere from a few thousand dollars to over $10,000.
  • How Much Do You Value Convenience? A standby generator is pretty much plug-and-play. Once you get it hooked up, it comes on automatically whenever the power goes out. Portable generators take a lot more work. You have to buy and store fuel for them ahead of time and run them regularly every month to make sure they’re working properly. Then, when a power outage hits, you have to haul out the generator, take it outside to hook it up, and get it running. If the power outage goes on long enough, you’ll have to run back out to add more fuel, potentially mid-storm. Finally, you have to take more precautions with a portable generator. If misused, it could start a fire or send harmful fumes into your house.
  • Where Will You Store It? If you choose a portable generator, you need to find a suitable place to store it. It has to be indoors to prevent it from getting damaged or stolen, but it also has to be easy to haul outdoors when you need it. You also need to have a suitable place to set it up during use: outdoors on level ground, protected from rain, but not too close to the house. With a standby generator, wherever you set it up is where it will live year-round. That saves you trouble, but it also takes a sizable chunk of space out of your yard — not just during storms, but all the time.
  • Do You Need Power While You’re Away? One advantage of a standby generator is that it will come on automatically, even if you’re not home when the power goes out. That means that if a storm hits your home while you’re away on vacation, you don’t have to worry about coming home to a flooded basement because the pipes burst or the sump pump stopped working.

Choose a Fuel Source

Once you’ve decided on a type of emergency generator, you need to decide what kind of fuel you want it to use. There are three possibilities:


The most popular fuel for a portable generator is gasoline. The most significant advantage of this fuel is that it’s easy to buy at any gas station. However, it’s not always available during emergencies. If a power outage strikes your whole area, not just your house, gas stations won’t be able to use electricity to pump their gas.

That means if you have a gasoline-powered generator, you need to keep an adequate supply of fuel on hand. However, that’s not always easy to do. Storing large amounts of gasoline is a fire hazard, and many local fire departments put a limit on the amount you’re allowed to store on your property. According to Family Handyman, the limit in most places is 25 gallons.

Also, according to the Chainsaw Journal, gasoline goes bad over time. Gas with ethanol — which is most of the gas sold these days — typically lasts only one month. Adding a fuel stabilizer can expand its lifetime to a year, but that still means replacing your entire supply every 12 months.

Gasoline can also be awkward to use since you have to fill the generator from a can with a funnel, and it gives off smelly fumes. As for the price, it varies widely from place to place, so the cost of running a gas generator depends on how much gasoline costs in your area.


You can buy both portable and standby generators that run on propane, which they sell in tanks at big-box stores like Home Depot and Walmart and sometimes grocery and convenience stores. Propane isn’t always as easy to buy as gasoline since, in many places, you can’t just run down to the nearest gas station for it. On the plus side, it’s safer to store and lasts virtually forever.

Propane also burns cleaner than gasoline. Not only is there no unpleasant smell, but it also produces less CO2 for the same amount of heat based on data from the U.S. Energy Information Administration (EIA).

According to the EIA, propane currently costs about $2 per gallon, which is cheaper than the average price per gallon for gasoline. However, as this chart from the Alternative Fuels Data Center shows, a gallon of propane only produces about 73% as much energy as a gallon of gas, so propane can be more costly to use. Propane-burning portable generators tend to be a little bit pricier than gasoline-burning ones, but they also last longer and cost less to maintain.

One big downside of propane is that the tank can’t always maintain enough pressure to keep the fuel flowing in very cold temperatures. To avoid this problem, homeowners in cold climates must make sure to refill their propane tanks when they’re at least one-quarter full, according to Ehrhart Energy.

Natural Gas

If you choose a standby generator and your home already uses natural gas for heating, you can simply hook the generator up to your gas lines. Natural gas tends to be cheaper than propane, but its most significant advantage is convenience. There’s no need to buy and store fuel or refuel the generator when it runs out. You have a steady supply flowing right through the pipes.

However, natural gas isn’t an option for portable generators, and it’s not practical if you don’t have natural gas service at home.

Get the Right Size

When it comes to generators, size matters. A generator that’s too small won’t meet your family’s power needs, but one that’s too big will cost more to buy and maintain.

Generators come in three basic sizes:

  • Small. The smallest portable generators put out up to 4,000 watts of power. These mini-generators supply enough power to keep a few essential appliances going, such as a refrigerator, sump pump, and a few lights. They usually have a built-in inverter. Many are even small enough to take with you on a camping trip.
  • Midsize. A midsize portable generator or small standby generator can produce between 5,000 and 8,500 watts of electricity. It can power everything a small portable generator can, along with extras like a computer, a portable heater, and a window air conditioner or fan for a gas furnace. At the upper end of this range, you could possibly power an electric water heater as well.
  • Large. Large generators, which only include standby generators, produce 10,000 watts or more. That’s enough to power an electric range or even a central air-conditioning system, along with everything else. The largest stationary models put out over 15,000 watts — enough to run an entire electric heating system.

To figure out what generator size you need, look at all the appliances you want to run during a power outage. Check the manual for each one to figure out how many watts of power it uses while running. If you don’t have the manual, Homelite has a chart that can provide a rough estimate of how much power various gadgets use.

Add up the wattages for all your devices, and you’ll know how much capacity your generator would need to keep everything running at once.

But you don’t necessarily need to run all your devices at once. Some appliances, such as a refrigerator, need power 24/7, but you can switch others in and out as needed. For instance, a microwave oven uses about 1,000 watts, but you only need to use it for a few minutes at a time. If you unplug your window air conditioner when you need to use the microwave, then plug it back in when you’re done cooking, you can get by with a smaller generator.

One other factor to consider is each appliance’s peak wattage. That’s the amount of power a device uses when running at its highest level — typically when you first start it up.

For instance, as the chart shows, a small sump pump takes about 800 watts to run but uses 1,300 watts at startup. That means that to avoid overloading your generator, you have to make sure it has 1,300 watts of spare capacity when you turn on the sump pump. You can probably manage that by turning a few other appliances off temporarily, but it’s something you’ll need to keep an eye on.

Useful Features

Finally, think about what features you want most in a generator. Useful options include:

  • Electric Start. Most portable generators use a pull cord to get them started. However, some come with a push-button battery starter, which is easier to use. The battery isn’t always included with the generator, so it could add an extra $50 or so to the cost.
  • Gauges. A fuel gauge shows you at a glance how much fuel a portable generator has left in the tank. It comes in handy during prolonged power outages when you’re likely to need to top it off several times. Another useful gauge is an hour meter, which keeps track of how many hours the unit has run. That tells you when it’s time for an oil change or other routine maintenance.
  • Low Oil Shutoff. This feature protects the generator from damage by shutting it off if the oil level gets too low. It’s standard on most stationary generators, but many portable models also include it.
  • Automatic CO Shutoff. Newer generators often come with built-in carbon monoxide (CO) sensors. If CO builds up to dangerous levels, it trips a switch that shuts off the generator. According to Consumer Reports, generators from Generac, Cat, and DeWalt all offer this feature. Other generator brands, such as Ryobi and Echo, offer low-CO engines to reduce the risk of carbon monoxide poisoning.
  • Multiple Outlets. If your generator isn’t hooked up to your household electrical panel with a transfer switch, you need one with multiple outlets so you can plug in several devices at once. Most portable generators have at least two electrical outlets, and some have four or more.
  • Dual-Fuel Use. Most portable generators run on gasoline only or propane only. However, the most versatile models, known as dual-fuel generators, can run on either one. This feature adds about $100 to the cost of a generator, according to Portable Generator Grader. There are even tri-fuel generators that can run on gasoline, propane, or natural gas, but these are very rare.
  • Inverter Technology. Most portable generators are subject to occasional power surges. These pose no problem for most appliances, but they can damage sensitive electronic gadgets. Generators with built-in inverters get around this problem by converting the generator’s alternating current (AC) to direct current (DC) and then back to AC, smoothing over any surges. According to Honda, inverter generators are typically smaller, lighter, more fuel-efficient, and much quieter than other portable generators. However, they’re also pricey and limited in output. A typical inverter generator costs around $1,000 and produces only 2,000 watts of power.

Shopping for a Backup Power Generator

The best time to buy a generator is before you need it. If you wait until a big storm is approaching to rush out to the nearest home center, its shelves are likely to be empty. Even if you manage to take home a generator, you’ll be forced to settle for whatever model the store has in stock.

Planning your purchase gives you time to do some research, choose the generator that’s right for you, and shop around for the best deal.

Once you know what kind of generator you’re looking for, consult product review sites, such as Consumer Reports, Popular Mechanics, and Wirecutter. These sites can tell you how different models perform in terms of power production, fuel use, reliability, noise, and user-friendliness. You can use this information to choose a generator that meets your needs and then look for local dealers that carry that particular model.

One other factor to think about before you buy is what you’ll do if the generator needs repairs. If you buy a stationary generator, you can simply call the contractor who installed it for you. However, when a portable generator breaks, you usually have to haul it into one of the manufacturer’s approved service centers to get it repaired under warranty.

So, before you settle on a brand, it’s worth checking to see where the nearest service center is and how easy it would be to take the generator there if you needed to.

Installing Your Portable or Standby Generator

The final step in buying a generator is to get it installed. If you buy a standby generator, you must find a qualified contractor to do the installation for you. If you purchase a portable generator, you can just find a suitable spot to set it up when the power goes out and plan to connect your appliances with extension cords.

However, experts say that if you have a portable generator of at least 5,000 watts that you expect to use often, it’s worth hiring an electrician to install a transfer switch. A transfer switch is a device that lets you safely hook up your generator to your circuit panel with a single cable.

When you want to run the generator, all you have to do is plug in the cable and flip a few switches to direct power to the panel from the generator rather than the grid. It’s both easier and safer than messing with multiple extension cords.

A transfer switch only works with generators of 5,000 watts or more. It keeps the generator cut off from the electrical grid, preventing power surges that could damage the generator, fry your appliances, and endanger utility workers. It’s also the only way to use your generator to power anything that’s hardwired into your home, such as a well pump or furnace. According to Consumer Reports, it costs between $500 and $900 to have one installed.

A cheaper alternative to a transfer switch is an interlock kit, which costs $100 to $200 less and is quicker to install. This device goes on the front of the circuit panel and ensures that power can only flow from the generator to the house and not the other way around. That means that if the power comes back on, it can’t back-feed into the generator, possibly damaging it. It also prevents the generator from feeding power into the grid, potentially electrocuting workers trying to repair the power lines.

How to Use a Generator

Simply owning a generator isn’t enough to protect you in an emergency. You also need to know how to use it. You don’t want to be out in the rain when a storm hits, fumbling in the dark with gas cans and power cords trying to figure out how to get the thing started.

To avoid this problem, you have to take the time, before a storm hits, to learn all about your generator — how to set it up, run it safely, and maintain it.

How to Start Your Generator

If you have a standby generator, it will come on automatically whenever the power goes out.

But with a portable generator, getting it started is a lot more complicated. Your generator’s manual should explain precisely how to do it, but Electric Generators Direct offers a quick rundown of the process. Essentially, you just:

  1. Wheel the generator into its outdoor position.
  2. Check the oil and fuel levels. If it’s a gas-powered generator, fill up the fuel tank with fresh gasoline. Also, top off the oil if the level is low.
  3. Make sure there are no cords connected to the generator.
  4. Turn on the fuel valve, then the choke, then the ignition switch — in that order.
  5. Start the generator. If it has an electric start, simply push the button. Otherwise, pull the cord until you feel resistance, then let it go. It may take more than one pull to get it started.
  6. Let it run for a few minutes, then set the choke back to the open (or “run”) position.
  7. Connect the generator. If you’re using individual extension cords, simply plug them into the outlets on the generator. If you have a transfer switch, connect the generator power cord to the power inlet box in your house.

Safety Considerations

A properly installed standby generator requires no further safety precautions.

By contrast, portable generators pose three major safety hazards: carbon monoxide poisoning, electric shock, and fire. To avoid these dangers, always follow the instructions in the manual to the letter. Here are a few general safety tips to keep in mind:

  • Never Run the Generator Indoors. To prevent CO poisoning, always run the generator in an open, outdoor space. Even a partially enclosed space, such as a garage with the door open, can trap enough carbon monoxide to be deadly. Keep the generator at least 20 feet away from the house and well away from any doors, windows, or vents that could admit fumes.
  • Use a CO Detector. If your generator doesn’t have an automatic carbon monoxide detector, install battery-operated CO detectors on every level of your house to further reduce the risk of CO poisoning. Test the batteries often to make sure they’re working. If the CO alarm goes off, quickly get outdoors or next to an open door or window.
  • Keep the Generator Dry. A generator could electrocute you if you run it in wet conditions. If you have to use it in the rain, keep it covered with an open, canopy-like structure, such as a tarp set up on poles. You can also buy a specially designed ventilated generator tent at a home center.
  • Use the Proper Power Cords. If you don’t have a transfer switch, make sure you’re plugging your appliances into the generator properly. Either plug them in directly or use heavy-duty extension cords designed for outdoor use. Ensure the cord is in good condition, with no cuts or tears, and has a three-prong plug. Also, check the extension cord’s amp or watt rating, and ensure it’s at least as high as the total wattage of all the appliances you’re hooking up to it.
  • Never Back-Feed. Plugging a generator directly into one of your home’s wall outlets is called “back-feeding,” and it’s extremely dangerous. It bypasses the circuit board in your house, meaning you could fry your electronic devices or, worse, start an electrical fire. Back-feeding also puts utility workers and neighbors who use the same power transformer at risk of electrocution.
  • Avoid Overloading the Generator. Even if your generator is hooked up properly, it’s possible to overload it, causing the generator to overheat or break down. To avoid this problem, keep an eye on how many appliances you’re running simultaneously, and don’t exceed the total amount of power the generator can produce. Most transfer switches help with this by displaying current usage, according to Consumer Reports.
  • Cool It Down Before Refueling. Never attempt to refuel a generator while it’s running. If you spill gasoline on a hot engine, it could start a fire. Turn the generator off and give it time to cool down before adding gas. That also reduces your risk of burning yourself on the hot engine.
  • Store Fuel Safely. Always use the type of fuel recommended for your generator. Keep extra fuel in an approved safety can, and store it in a cool, well-ventilated area. Stash your extra fuel in a locked area, but don’t keep it in your home’s living areas or anywhere near a fuel-burning appliance, such as a natural gas water heater in the garage. Check with your local fire department to find out how much fuel you’re allowed to store on your property and where you’re allowed to put it.


If you want your generator to be ready to go when the power grid goes down, you need to maintain it properly. The manual should provide details about taking care of your generator, but there are some basic guidelines everyone should follow.

  • Have Enough Fuel. According to the Consumer Reports buying guide, it takes 12 to 20 gallons of gasoline to run a generator for a full 24 hours. Since propane supplies 0.73 times as much energy per gallon as gasoline, that’s equivalent to about 16 to 28 gallons of propane. However, you probably don’t need to keep your generator running 24/7. Turning it on once every few hours could be enough to power your essential appliances, such as the fridge and freezer. According to the U.S. Food and Drug Administration, food will typically stay cold for about four hours in an unopened refrigerator and around two days in a full, unopened freezer. You can store propane indefinitely, but gasoline needs to be fresh or the generator might not run properly. Experts recommend adding a fuel stabilizer, which keeps gasoline in cans good for up to a year. Doing so also means you don’t need to drain the generator’s tank when you’re done using it.
  • Check the Oil. To avoid damaging your generator, make sure it has enough oil before you start it. However, be careful not to overfill it. Add just enough oil to hit the full mark on its dipstick.
  • Change the Oil. The first time you use your generator, change the oil after running it for five hours. After that, it should be able to go about 100 hours between oil changes. Check your owner’s manual to find out what type of oil to use.
  • Check the Filters. Each time you run the generator, check the filters. If they’re visibly dirty, replace paper filters. Or clean foam ones in soapy water. Let them dry, and oil them with foam filter oil as directed in the manual. If your generator has a filter cup in the opening of the fuel tank, clean it by tapping out any debris and wiping it with a clean rag. Finally, some generators have a fuel filter installed in the fuel line. Check the manual to find out when and how to change this filter.
  • Check the Spark Plug. Typically, a generator spark plug needs to be replaced after a certain number of hours of use, which should be listed in the manual. If you don’t have an hour gauge, keep track of how many hours your generator has run to ensure you know when it’s time to change it.
  • Run It Dry. If you’re expecting your generator to sit idle for at least two weeks, empty the fuel lines before you put it away. To do this, turn off the fuel valve while the engine is running and let it run down. That clears fuel out of the lines and the carburetor to keep them clean, and it also prevents leaks.
  • Run It Regularly. Once per month, start up your generator and let it run for about 20 minutes. It burns off moisture, lubricates the engine, and recharges the battery. Also, consider doing a test run every few months by hooking the generator up to the transfer switch and making sure it can power everything you need it to.
  • Store It Properly. Don’t leave your generator outdoors between uses. Instead, store it in a shed or garage, where it’s protected from the weather.

Final Word

Your neighbors are likely to feel a little jealous when yours is the only house on the block with power. To stay on good terms with them, be considerate about how you use your generator. Try to put it in a location where the noise won’t be too bothersome, and if you can, avoid running it late at night.

Also, be a good neighbor by offering to share some of the power your generator produces. Even if you can’t spare enough power to let them physically plug into the generator, you can invite them into your house to charge up their cellphones or offer to store some food in your fridge for them. That way, you can be the most popular family on the block during a power outage instead of “those jerks with the noisy generator.”

Finally, remember that having a generator isn’t the only way to prepare for a natural disaster. Take the time to learn more about other tips that can help you, such as stocking up on food and learning first aid.

Amy Livingston is a freelance writer who can actually answer yes to the question, "And from that you make a living?" She has written about personal finance and shopping strategies for a variety of publications, including,, and the Dollar Stretcher newsletter. She also maintains a personal blog, Ecofrugal Living, on ways to save money and live green at the same time.