The average American home lost power for just over five and a half hours a year a decade ago. Today that number is closer to eight — and in storm-prone states, it’s far worse. Outages aren’t just longer; they’re happening in clusters, which is why the aisle of generators at your local home center is suddenly three times the size it used to be.
So you start shopping, and within about ten minutes you hit the wall every homeowner hits: a portable generator costs a few hundred dollars and you can buy it this afternoon. A standby generator costs as much as a used car and needs an electrician, a gas line, and a permit. Both claim to keep your lights on. Nobody tells you which one you actually need.
That’s what this guide is for. By the end, you’ll know exactly which side of the standby generator vs portable generator question your house falls on — and, just as importantly, when the answer is “neither, yet.”
The Real Difference Isn’t Power — It’s What Happens at 3 A.M.
Most comparisons start with wattage. That’s the wrong starting point, because you can buy portable units that produce plenty of power and standby units that produce modest amounts. The meaningful difference is automation and fuel.
A portable generator sits in your garage. When the power goes out, someone has to go get it, roll it outside, fill it with gasoline, start it, and run extension cords into the house. It runs as long as you keep feeding it fuel — typically 8 to 12 hours per tank, which means refueling in the dark, in the rain, while the storm is still going.
A standby generator is bolted to a concrete pad outside your house, wired into your electrical panel through an automatic transfer switch, and connected to your natural gas or propane supply. When the utility power drops, it detects the loss, starts itself within about 10 to 30 seconds, and powers the circuits you chose ahead of time. Nobody has to be home. Nobody has to do anything.
That’s the actual product you’re buying with a standby unit: you’re not buying electricity, you’re buying the elimination of a middle-of-the-night chore during the worst weather of the year.
What Each One Costs (Realistically)
Ballpark figures vary by region and by how complicated your installation is, but here’s the honest shape of it:
- Portable generator, 3,000–5,000 watts: roughly $400–$900. Runs a fridge, some lights, a few outlets, maybe a window AC.
- Portable inverter generator, 2,000–4,000 watts: roughly $600–$1,500. Quieter, cleaner power that’s safer for electronics, but usually less raw output per dollar.
- Large portable, 7,500–10,000 watts: roughly $900–$2,000. Can run much of a small home if paired with a manual transfer switch.
- Standby generator, unit only, 10–24 kW: roughly $3,000–$7,000.
- Standby installation: often another $3,000–$6,000 — electrician, transfer switch, gas line work, concrete pad, permits, inspection.
Two costs people consistently forget. First, a portable generator needs a manual transfer switch (typically $500–$1,500 installed) if you want to power hardwired things like your furnace or well pump — running extension cords will never reach those. Second, a standby generator needs annual maintenance, usually $200–$400 a year for oil, filters, and a load test.
The Fuel Question Decides More Than People Expect
Here’s the part that quietly settles the argument for a lot of households.
A portable generator running on gasoline burns roughly 0.5 to 1.5 gallons per hour depending on load. A three-day outage means somewhere between 25 and 60 gallons of gas — while every station within twenty miles either has a line around the block or no power to run its pumps. Gasoline also goes stale in about 30 days without stabilizer, so the five-gallon can you filled last spring may not start your generator this fall.
A standby generator on natural gas has, functionally, an unlimited fuel supply, because the gas main almost never goes down with the electric grid. On propane, a 500-gallon tank will typically run a mid-size unit for a week or more. No cans, no gas station, no stale fuel.
So the length of the outages in your area matters more than the frequency. Four two-hour blips a year? A portable handles that fine. One five-day ice storm every couple of winters? That’s a very different calculation.
Real Talk: I Bought the Wrong One First
A few winters back I did what most people do — grabbed a mid-size portable on sale, felt very prepared, and stuck it in the corner of the garage. Then the power actually went out, at about eleven at night, in freezing rain.
Getting it outside was fine. Getting it started after eight months of sitting with old fuel in the carburetor was not. I pulled that cord for twenty minutes in the sleet before it caught. Then I discovered the extension cords I owned wouldn’t reach the fridge and the space heater at the same time, and that the furnace — the thing I actually wanted — was hardwired and completely out of reach.
The generator worked exactly as advertised. My plan was the thing that failed. If you go portable, buy the transfer switch, buy fuel stabilizer, and run the thing for fifteen minutes every three months. That’s the whole difference between owning a generator and being prepared.
How to Decide: Four Honest Questions
- How long are your outages, typically? Under 4 hours, portable. Multi-day, standby.
- Is anyone home to run it? If your household travels, or if someone can’t safely wrestle a 150-pound machine outside, the automation of a standby unit isn’t a luxury — it’s the entire point.
- What must not fail? A well pump, sump pump, medical equipment, or a home business that can’t take downtime pushes hard toward standby. A fridge and some lamps doesn’t.
- Do you have natural gas at the house? If yes, standby gets meaningfully cheaper and simpler. If you’d need a new propane tank, add that to the budget.
The Safety Rules That Aren’t Optional
This is the one section to read twice, because generator mistakes kill people every single storm season.
- Never run a portable generator indoors — not in a garage, not in a shed, not on a covered porch, not with the door open. Carbon monoxide is odorless and builds fast. Keep it at least 20 feet from the house with the exhaust pointed away.
- Never “backfeed” by plugging a generator into a wall outlet. It energizes the utility lines outside and can electrocute a line worker. This is why the transfer switch exists.
- Let it cool before refueling. Gasoline on a hot engine is exactly what it sounds like.
- Put a battery CO alarm on every level of the house before you ever need the generator.
The Standout Tip: Size It by Circuit, Not by House
If you take one thing away, take this. Almost everyone shopping for a generator asks “how many watts do I need to run my house?” — and gets scared off by the answer, because running an entire home takes a big, expensive unit.
Ask a better question: which circuits do I actually need during an outage? Walk your electrical panel with a notepad and mark them. For most homes the honest list is short — furnace blower, refrigerator, sump or well pump, a few lighting circuits, and the outlets where phones and a router live. That’s often 5,000 to 8,000 watts, not 20,000.
Sizing by circuit routinely moves people down a full tier in the standby generator vs portable generator decision — into a smaller, cheaper standby unit, or into a properly wired portable setup that does 90% of the job for a quarter of the price. The AC and the electric dryer can wait until Tuesday.
Take that circuit list to two electricians for quotes before you buy anything. It’s a free half hour that will tell you more about your real options than a month of shopping ever will.
