A portable electric generator is the middle ground between a flashlight and a whole-house standby system — enough power to keep your essentials running through an outage, small enough to roll into the yard, and priced anywhere from $150 to $1,200. Whether you need one for storm backup, a job site, or tailgating, the buying decision comes down to how much wattage you need and how well you follow a few non-negotiable safety rules.
Choose the right portable electric generator and you’ll never sweat a power outage again. Choose wrong on size or ignore the carbon monoxide and backfeed warnings, and you’ve either wasted money or put your family at real risk. Here’s how to get it right.
Running Watts vs Starting Watts
Every generator carries two ratings, and confusing them is the most common sizing mistake. Running watts is the steady power the unit supplies continuously. Starting watts — also called surge watts — is the extra burst it can deliver for a second or two when a motor spins up. Refrigerators, air conditioners, and pumps all draw two to three times their running wattage at the instant they start.
So a generator labeled “4,000 starting / 3,200 running” gives you 3,200 continuous watts and 4,000 for surges. Always size by running watts for your total load, then confirm the surge rating covers the startup spike of your single largest motor.
How to Size Your Generator
List every device you need during an outage and total up their running watts. Common household draws:
- Refrigerator/freezer: 600-800 watts running, up to 1,200 starting
- Furnace blower: 600-900 watts
- Sump pump: 800-1,050 running, 1,500-2,200 starting
- Window AC (10,000 BTU): 1,200 running, 1,800 starting
- Lights throughout the house (LED): 150-300 watts
- TV and electronics: 100-400 watts
- Well pump (1/2 HP): 1,000 running, 2,100 starting
- Coffee maker or microwave: 800-1,200 watts
Total your essentials and add 20% headroom so the engine never runs maxed out. Most homeowners keeping a fridge, furnace blower, lights, and electronics alive need roughly 3,000 to 4,000 running watts. Add air conditioning or a well pump and you climb toward 5,000 or more. If you only need to charge devices and run a couple of lights, 1,000 to 2,000 watts is plenty.
Run Time and Fuel Options
Run time is a function of tank size and load. A mid-size unit with a 3- to 4-gallon tank runs 8 to 10 hours at half load; heavier loads shorten that considerably. Most portable generators burn gasoline, but dual-fuel models also accept propane. Propane stores for years without going stale and burns cleaner, which is a real advantage for a machine that might sit unused for months between outages — the trade-off is a small drop in wattage output.
Keep 5 to 10 gallons of fresh, stabilized gasoline on hand before storm season. Untreated gas breaks down in about a month and clogs the carburetor, so add fuel stabilizer to anything you store. Run the generator dry or run stabilized fuel through it before long-term storage.
Inverter or Conventional?
Conventional open-frame generators cost less and deliver strong power, but the electricity has more voltage fluctuation. That’s fine for resistive loads like lights, heaters, and fridges, but it can damage sensitive electronics. Inverter generators condition their output into clean, stable power safe for laptops, phones, and TVs. They also run quieter and sip less fuel because the engine throttles to match demand.
For basic outage backup, a conventional unit at $300 to $600 does the job. If you’re powering computers or medical devices, or you want a quiet machine, an inverter at $500 to $1,200 is the smarter buy.
Price by Power Class
- 1,000-2,000 watts: $150-$700 — device charging, lights, small appliances
- 3,000-4,000 watts: $300-$900 — fridge, furnace blower, lights, and electronics together
- 5,000-6,500 watts: $500-$1,200 — near-whole-home essentials including AC or a well pump
Look for useful features at any price: an electric-start button beats yanking a pull cord, a fuel gauge tells you when to refill, multiple 120-volt outlets plus a 240-volt outlet add flexibility, and wheels with a folding handle make a heavy unit actually portable.
Using Extension Cords Correctly
If you’re not installing a transfer switch, extension cords are how you get power from the generator to your appliances — and using the wrong cord is a real fire hazard. Match the cord gauge to the load and length: a lighter 16-gauge cord is fine for lamps and chargers, but a fridge or pump on a long run needs a heavy 12- or 10-gauge outdoor-rated cord. Undersized cords overheat, drop voltage, and can damage motors.
Use cords rated for outdoor use with a grounded three-prong plug, keep them out of standing water, and never chain multiple cords together to reach farther than one properly sized cord should. Uncoil the cord fully when it’s in use — a tightly wound cord under load traps heat and can melt its own insulation.
Where to Place the Generator
Set the generator on firm, level ground so the engine lubricates properly and doesn’t tip. Keep it at least 20 feet from the house with the exhaust aimed away from every opening. Protect it from rain and snow under an open-sided canopy or a purpose-built generator tent — never a closed shed or the garage. Give it a couple of feet of clearance on all sides for cooling airflow, and chain it to a fixed anchor if theft is a concern, since a running generator on a driveway is an easy target during a widespread outage.
Carbon Monoxide Kills — Run It Outside
This is the rule you never break. A portable electric generator’s engine produces carbon monoxide, a gas you can’t see or smell that causes death within minutes at high concentration. Never operate one indoors, in a garage, in a shed, in a basement, or on a covered porch — not even with doors and windows open. CO accumulates and drifts into living spaces, and an open garage door does not make it safe.
Always run the generator outdoors, at least 20 feet from the house, with the exhaust aimed away from any window, door, or vent. Buy a model with an automatic CO shutoff sensor, and install battery-powered CO alarms inside your home as a second line of defense. No amount of convenience is worth the risk of running an engine anywhere near enclosed space.
Never Backfeed Your Panel
Plugging a generator into a wall outlet to energize your house wiring — backfeeding — is deadly and illegal in most jurisdictions. It sends power backward onto the utility lines where it can electrocute repair crews, and it bypasses your home’s breakers, creating a fire hazard. Do not do it, no matter what video you saw online.
The safe ways to use your generator are two: run heavy-duty, outdoor-rated extension cords directly to each appliance, or have a licensed electrician install a manual transfer switch. A transfer switch ($500 to $900 installed) connects the generator to your electrical panel and physically disconnects the utility feed, so you can safely power hardwired circuits like your furnace and well pump. It’s the only legitimate way to feed your home’s built-in wiring.
Safety and Maintenance Checklist
- Operate outdoors only, 20+ feet from the home, exhaust pointed away.
- Choose a unit with automatic CO shutoff and install indoor CO alarms.
- Let the engine cool 5-10 minutes before refueling — never fuel a hot engine.
- Keep the generator dry under an open canopy; never enclose it.
- Never backfeed; use extension cords or a professionally installed transfer switch.
- Change the oil per the manual — often after the first 20-25 hours, then every 50-100.
- Run it briefly every month or two so it starts reliably when you need it.
A properly sized portable electric generator turns a multi-day outage from an ordeal into an inconvenience. Add up your running watts, build in 20% headroom, keep stabilized fuel ready, and treat the carbon monoxide and backfeed rules as absolute. Do that, and your generator will deliver exactly the peace of mind you bought it for.
