Choosing a generator for your home comes down to four decisions: what you want to keep running, how the generator will connect to those things, which fuel you can store or supply, and how much effort you are willing to put in during an outage. Work through them in that order and the right type of generator usually becomes obvious.
Quick answer
If outages are occasional and you only need the essentials, a 5,000 to 7,500 watt portable generator with a transfer switch or interlock is the most economical choice. If outages are long or frequent, someone at home depends on powered equipment, or nobody can be there to start a portable unit, a permanently installed standby generator is worth its much higher cost.
In this guide
Step 1: Decide what has to stay on
Walk through the house and sort everything electrical into three groups.
- Essential: refrigerator and freezer, furnace blower or boiler controls, sump pump, well pump, medical equipment, a few lights, phone and internet.
- Useful: microwave, coffee maker, television, garage door opener, washing machine.
- Heavy: central air conditioning, electric water heater, electric range, clothes dryer, electric heating, EV charging.
The essential group in a typical home adds up to roughly 3,000 to 5,000 running watts. Adding the heavy group can push the total past 15,000 watts, which is standby-generator territory. Be honest about which of the heavy loads you could live without for a few days. That single decision changes the size and cost of the system more than anything else.
Step 2: Pick the type of generator
| Type | Power | Starts | Best for | Keep in mind |
|---|---|---|---|---|
| Inverter generator | 2,000 to 5,000 W | By hand or button | Apartments and small homes, a refrigerator and electronics | Limited output and usually 120 V only |
| Portable generator | 5,000 to 12,000 W | By hand or button | Essentials in most houses, including a well pump | You must wheel it out, fuel it and connect it |
| Standby generator | 10 to 26 kW and beyond | Automatically | Whole-house backup, frequent or long outages | Professional installation and a much higher cost |
| Portable power station | 1 to 5 kWh of stored energy | Instantly, silently | Short outages, apartments, medical devices indoors | Limited energy, slow to recharge without sun or grid |
Portable generators
A portable generator is the lowest-cost way to cover the essentials. The trade-off is effort. Somebody has to move it outside, start it, refuel it every 8 to 12 hours and put it away afterwards. See our guide to the best types of portable generator for sizes and features.
Inverter generators
Inverter generators are quieter, lighter and easier on fuel, and their clean power suits electronics. They make sense for smaller homes, townhouses with close neighbors, and anyone who also wants a generator for camping. Read inverter vs conventional generators for the full comparison.
Standby generators
A standby generator sits outside on a pad like an air-conditioning unit, runs on natural gas or propane, and starts by itself within seconds of an outage. It is the only type that protects the house when you are away. Our guide to whole-house generators explains sizing, fuel and installation, and portable vs standby compares the two approaches directly.
Portable power stations
Battery power stations are not generators, but they solve some of the same problems. They are silent, produce no exhaust and can be used indoors, which makes them a good fit for apartments and for keeping a medical device or a refrigerator running through a short outage. Their weakness is capacity. Once the battery is empty you need the grid, solar panels or a generator to refill it.
Step 3: Decide how it will connect
There are only three safe ways to get generator power to your appliances.
- Extension cords. Run heavy-duty, outdoor-rated cords from the generator to individual appliances. Simple and cheap, but it cannot power hard-wired equipment such as a furnace or well pump.
- A manual transfer switch or interlock. An electrician installs a power inlet on the outside wall and a switch at your electrical panel. You plug the generator into the inlet with one cord and choose which circuits to run.
- An automatic transfer switch. Used with standby generators. It detects the outage, starts the generator and switches the house over without anyone touching it.
Our step-by-step guide to connecting a generator to your house covers each option, the parts involved and what to ask an electrician.
Step 4: Choose a fuel
| Fuel | Storage life | Strengths | Weaknesses |
|---|---|---|---|
| Gasoline | A few months, up to a year or two with stabilizer | Available everywhere, highest output | Goes stale, hard to find during wide outages, flammable to store |
| Propane | Indefinite | Clean, stores for years, easy to stockpile in cylinders | About 10 percent less output, cylinders can ice up in the cold |
| Natural gas | Not stored: piped in | Unlimited run time, no refueling | Needs a gas line, can be shut off after earthquakes |
| Diesel | Six to twelve months, longer with treatment | Efficient, safer to store than gasoline | Costlier machines, cold-weather fuel problems |
For emergency use, where a generator may sit for months between outages, dual-fuel generators are popular because propane never goes stale. If you stay with gasoline, read how long gasoline lasts and rotate your stored fuel.
Step 5: Be realistic about ownership
A generator that will not start is the most common outage story of all. Whatever you buy, plan to:
- Run it under load for 20 to 30 minutes about once a month.
- Keep fresh, stabilized fuel on hand, or use propane.
- Change the oil on schedule, including after the short break-in period on a new engine.
- Store it where you can get it outside easily, with its cords and a fuel funnel.
- Fit battery-backed carbon monoxide alarms on every level of the home.
The generator maintenance checklist sets out the full schedule.
What does a home generator cost to own?
Prices change too often to quote reliably, but the pattern is consistent. A portable generator with an inlet box and interlock or manual transfer switch is the lowest-cost complete setup. A standby system costs several times more once the pad, electrical work, gas plumbing and permits are included, and installation is often as much as the generator itself. Get at least two written quotes for any installed system, and ask what is included.
Fuel is the main running cost. As a rough guide, a portable gasoline generator carrying a typical household’s essentials uses 5 to 10 gallons a day when run around the clock. See how much gas a generator uses for the numbers and ways to cut them.
Frequently asked questions
What size generator do I need for my home?
Add the running watts of everything you want to run at the same time, add the extra starting watts of the largest motor, then allow about 20 percent headroom. Most homes land between 5,000 and 7,500 running watts for essentials. Whole-house coverage with central air usually needs 18 kW or more.
Can I run a generator in my garage with the door open?
No. Carbon monoxide builds up in a garage within minutes, even with the door open, and it spreads into the house. Run the generator outdoors, at least 20 feet from the house, with the exhaust pointing away.
Is a standby generator worth it?
It is worth it when outages are frequent or long, when someone depends on powered medical equipment, when a sump pump protects a finished basement, or when the house is often empty. For a rare outage of a few hours, a portable generator does the job at a fraction of the cost.
Will a generator damage my electronics?
Inverter generators and standby generators produce clean power that suits electronics. Basic open-frame portables vary. If you will run computers or modern appliances from a conventional generator, look for a low distortion rating, and consider a surge protector or small battery backup for sensitive devices.
