A portable generator is bought for one reason: keeping the essentials running when the power does not. Because it is also a machine that produces carbon monoxide, the buying decision has a safety dimension most categories do not. Here is what to work through before purchasing.
Work out what you actually need to power
Make a list of what must run — refrigerator, freezer, medical devices, lights, a phone, maybe a router or a well pump — and what would be nice to have. Then learn the difference between running watts (the steady draw to keep an appliance going) and starting watts (the short surge some motors need to start). You will find both numbers on the appliance labels and in generator specifications: size the generator so its running watts cover your essentials and its starting watts cover the largest motor you will start. Buying far more generator than you need wastes fuel and money; buying too little means it cannot start what you bought it for.
Choose the type that fits your use
Conventional portable generators are the traditional workhorses. Inverter generators condition their output, which manufacturers describe as steadier power suited to sensitive electronics, and they typically run quieter by adjusting engine speed to the load. There are also permanent standby generators — installed, automatic, and wired into a transfer switch — but those are an electrician and a project, not a hardware-store pickup. For occasional outages and portability, the conventional-versus-inverter decision is the one that matters.
Check fuel and how it behaves over time
Most portable models run on gasoline; many also run on propane, and dual-fuel designs accept both. Propane stores far longer than gasoline, which matters for a machine that may sit unused for months. Whatever the fuel, runtime depends heavily on the load you draw — read the runtime figures at the load you expect, not at the lightest number on the chart — and plan for fuel storage and stabilizer if gasoline is your choice.
Treat carbon monoxide safety as a buying criterion
Generators exhaust carbon monoxide, an odorless gas that kills in enclosed spaces. Never run a generator indoors, in a garage, in a basement or near windows and doors — even "just for a minute." Look for a model with an automatic carbon-monoxide shutoff: the ANSI/PGMA G300-2018 safety standard provides one, and the U.S. Consumer Product Safety Commission has pursued federal safety requirements for exactly this hazard, citing large numbers of deaths in its rulemaking. A CO alarm where you run it is a cheap second layer.
Plan the connection before it arrives
For home backup, decide how the generator will connect: outdoor-rated cords to transfer-switched inlet points, or a professionally installed transfer switch or interlock so the generator and the grid cannot fight each other. Anything that ties a generator into household wiring should be evaluated by a licensed electrician. Also compare noise output between models — a generator you cannot tolerate running near the house at night is a generator you will not use well.
Before you buy
- Running and starting watts cover your real essentials list
- Inverter or conventional matches your use case
- Fuel choice matches how long the machine will sit
- Automatic CO shutoff and you have a safe location
- The connection method is planned, not improvised
A generator is insurance more than a purchase. Sizing it right and installing it safely is what turns it from an expensive metal box into the reason the freezer stayed cold.