Buying a generator you can't fuel.

A 5,000-watt generator running at half load burns through roughly 0.5 to 0.75 gallons of gasoline per hour. That's 12 to 18 gallons per day. Most households keep a single five-gallon gas can in the garage. At full load, that can is gone in about four hours.

This is the scenario that plays out in every extended power outage: households buy a capable generator, run it for one day, and then either scramble for fuel or shut it down entirely. A generator without fuel is a $600 noise machine that didn't help.

The fuel math you should do first.

Before choosing a generator, start with fuel capacity, not wattage. Ask: how much fuel can I realistically store, rotate, and replenish? That number determines your actual runtime. Work backward from there.

A standard 5-gallon gas can costs about $15. Most households can safely store two to four cans in a ventilated garage or shed. That's 10 to 20 gallons. At 0.5 gallons per hour for a typical 2,000-watt inverter generator at moderate load, 20 gallons gives you about 40 hours of runtime — roughly a week if you run it three to four hours per day rather than continuously.

Running a generator continuously is almost always a mistake. Most households don't need to keep the refrigerator cold around the clock. Run a few hours in the morning to chill the fridge, charge devices, and heat water. Run a few hours in the evening. The fuel lasts much longer and the noise is far less punishing for neighbors.

The propane solution.

Gasoline goes stale. Untreated gas begins to degrade in three to six months, forming varnish that clogs carburetors and fuel injectors. The generator you bought two years ago may not start on the fuel sitting in the tank.

Propane doesn't go stale. A 20-pound propane tank, the kind most households already own for a gas grill, contains about 4.7 gallons of propane equivalent. It costs $20 to $25 to fill at any hardware store. Dual-fuel generators (gasoline and propane) are available from about $500 and accept a standard grill-tank adapter. You can own three or four tanks, keep them full, rotate them through normal grill use, and always have ready fuel for the generator.

If you store gasoline, use PRI-G or Sta-Bil. Either product extends gasoline shelf life to one to two years. Treat every can when you fill it. Rotate the fuel before it ages out. Use treated stored fuel in lawn equipment so nothing sits forever.

Right-size the generator.

Most households do not need a 5,000-watt generator. They need a 2,000-watt inverter generator. A 2,000-watt inverter unit runs quieter, burns less fuel, produces clean power safe for electronics, and costs less. It will run a refrigerator, charge phones and laptops, power a CPAP, and run a small window AC unit.

What it won't run: a full central air system, an electric range, or an electric water heater. If those are requirements, you need a larger generator, a transfer switch, and a serious fuel plan. Most households, honestly assessed, don't need any of that for a week-long outage.