The Complete Guide to Buying a Portable Generator

Why You Need a Portable Generator

Power outages happen everywhere, and the trend is toward more of them, not fewer — aging grid infrastructure, more frequent severe weather events, and increasing demand all point toward a future where the power grid is less reliable than it was in previous decades. A portable generator is the single most practical emergency preparedness purchase most households can make. Unlike a flashlight collection or a cupboard of canned food, a generator keeps your refrigerator running (preventing $200-500 in food spoilage), your medical devices powered, and your home livable during extended outages.

Beyond emergency use, portable generators serve real weekend recreational purposes: camping with electrical power, RV and overlanding trips, outdoor concerts and festivals, tailgating, and powering tools at remote jobsites. The right generator for home backup may not be the right generator for camping — understanding the tradeoffs before buying saves you from owning the wrong tool for both jobs.

Types of Portable Generators Explained

Conventional Generators

Conventional portable generators produce AC power directly from the engine running at a constant 3,600 RPM (for 60Hz power). They're the loudest type of generator — typically 65-78 dBA, which is roughly equivalent to a garbage disposal or power drill. The constant-speed operation means they're less fuel-efficient than inverter generators under partial load because the engine runs at full speed regardless of how much power you're actually drawing. Conventional generators are typically less expensive per watt than inverter generators, making them the choice when maximum wattage at minimum price is the priority — such as running power tools, well pumps, and large appliances that don't require clean power.

The key limitation: conventional generators produce "dirty" power with harmonic distortion that can damage sensitive electronics (laptops, TVs, medical equipment). You can run a refrigerator on a conventional generator safely; you shouldn't run a laptop directly without a UPS or surge protector between them.

Inverter Generators

Inverter generators produce AC power, convert it to DC, then invert it back to clean AC through a microprocessor. The result is power with less than 3% total harmonic distortion — equivalent to utility grid power. The engine speed varies automatically with load demand, which makes inverter generators 20-40% more fuel-efficient than conventional generators at partial loads and significantly quieter (48-58 dBA).

Inverter generators are the right choice for camping, tailgating, and any application where sensitive electronics need power. The downside: they cost more per watt than conventional generators. A 2,000W inverter generator costs $400-1,100; a 2,000W conventional generator costs $300-500. For most recreational and moderate home backup use, the noise and fuel efficiency advantages justify the inverter premium.

Dual Fuel Generators

Dual fuel generators run on either gasoline or propane, switchable without shutting down (on most models). The strategic advantage: gasoline is the first fuel to disappear from stations during a major regional outage, while propane stores indefinitely in sealed tanks and can be stockpiled cheaply in normal times. A dual fuel generator running on a stockpiled propane supply is genuinely more disaster-ready than a gasoline-only generator. Propane output is typically 10-15% lower than gasoline output on the same engine — plan your watt requirements based on propane capacity. See our dual fuel generator comparison.

Solar Generators / Battery Power Stations

Battery-based "solar generators" (really battery power stations with AC inverters) produce completely silent, zero-emission power indoors. They're charged from wall outlets, car chargers, or optional solar panels. The tradeoff versus gas generators: significantly higher cost per watt of output, and capacity limited by battery size rather than fuel availability. A 1,000Wh battery power station ($500-1,200) can run a phone for days, a laptop for 10+ hours, or a refrigerator for 4-6 hours. They're excellent for outages measured in hours; inadequate for multi-day grid failures unless paired with solar charging. See our solar generator guide.

How to Size Your Generator

Generator sizing is the step most people get wrong — they either buy too small (frustrated when they can't run everything) or too large (paying for capacity they never use). The right approach:

Step 1: List Your Priority Loads

Write down everything you want to power simultaneously during an outage, in priority order:

• Refrigerator/freezer: 100-400W running, 800-1,200W starting surge
• Window air conditioner: 900-1,440W running, 2,200-3,600W starting surge
• Central AC (15,000 BTU): 1,500W running, 5,000W starting surge
• Sump pump: 800-1,050W running, 1,300-2,150W starting surge
• Well pump (1/2 HP): 1,000W running, 2,000W starting surge
• Portable heater: 1,500W running (no surge)
• LED lighting: 10-40W per fixture
• Phone/device charging: 100-300W total
• Laptop: 45-100W
• Television: 50-300W

Step 2: Calculate Your Minimum Wattage

Add the running wattage of everything you want to run simultaneously, then add the largest single starting surge on top. Example: refrigerator (200W) + sump pump (1,000W) + lighting (200W) + devices (200W) = 1,600W running. The sump pump surge (2,150W) added to everything else running: 1,600W + 2,150W = 3,750W needed peak. A 4,000W generator handles this scenario; a 2,000W generator does not.

Step 3: Add a Buffer

Add 20-25% to your calculated minimum wattage to account for motor degradation over time (motors draw more current as they age), temperature effects (generators produce less output in hot weather), and future load additions. That 3,750W minimum becomes a 4,500-4,700W target — a 5,000W generator is the right size for this scenario.

Fuel Considerations

Gasoline Storage and Stability

Fresh gasoline degrades significantly over 30 days without treatment. Ethanol-blended fuels (E10, which is standard at most stations) absorb moisture and separate, leaving water in the fuel that causes starting and performance problems. Store emergency fuel with a fuel stabilizer like PRI-G or Sta-Bil added at filling, and rotate stock every 6-12 months by using stored fuel in vehicles and refilling with fresh.

Propane Advantages

Propane stores indefinitely in sealed tanks at standard conditions. A stockpile of 100-200 lbs of propane (4-8 standard 20-lb grill tanks or a 100-lb tank) provides a meaningful extended-outage buffer. Propane burns cleaner than gasoline, leaving no fuel residue in carburetors — a common cause of generator starting failure after long storage periods. If you own a generator that sits unused for 6+ months between outages, propane capability is particularly valuable.

Noise and Safety

Generator Noise Levels

Generator noise is measured in decibels (dBA) at 23 feet. Here's context for the numbers:

• 48-54 dBA: Inverter generators at light load — similar to a quiet conversation
• 55-60 dBA: Standard inverter generators at full load — similar to a normal conversation
• 65-70 dBA: Conventional generators — similar to a vacuum cleaner
• 75-80 dBA: Large conventional generators — similar to a garbage disposal

Many campgrounds, HOAs, and neighborhoods have noise ordinances or generator time restrictions. Inverter generators under 60 dBA are acceptable in most campgrounds and residential areas during permitted hours.

Critical Safety Rules

Carbon monoxide poisoning from portable generators is a genuine, preventable cause of death. Every year, people die by running generators in garages, basements, or near open windows. The rules are absolute:

• Never run a gas generator indoors, in a garage, in a basement, or in any partially enclosed space — including spaces with open windows or doors
• Position the generator at least 20 feet from any door, window, or vent
• Point the exhaust away from occupied structures
• Install battery-powered carbon monoxide detectors on every floor of your home
• Never refuel a hot or running generator — let it cool for 10-15 minutes

Transfer Switches and Whole-Home Backup

To power hardwired home circuits (lighting, wall outlets, HVAC, etc.) from a portable generator, you need a transfer switch — a device that safely disconnects your home from the utility grid before connecting the generator, preventing dangerous back-feed that can electrocute utility workers. Never plug a generator into a wall outlet (a practice called "backfeed") — it's illegal in most jurisdictions and genuinely dangerous.

Manual transfer switches ($150-300) require you to physically flip breakers to switch circuits to generator power. Automatic transfer switches (ATS, $300-700+) sense a grid outage and switch automatically — no human action required. For a portable generator meant for home backup, budget for a transfer switch installation alongside the generator purchase. A licensed electrician should install any transfer switch; it's not a DIY project if you aren't licensed.

Maintenance Schedule

A generator that's neglected between outages won't start when you need it. Follow this maintenance schedule:

• Monthly: Run the generator for 30 minutes under moderate load. This charges the battery (on electric start models), circulates oil, and prevents carburetor gumming.
• Every 50-100 hours or annually: Change the oil (check your manual — Honda specifies 10W-30 for most temperature ranges). Inspect and clean or replace the air filter. Inspect and replace spark plugs if needed.
• Before storage (6+ months): Add fuel stabilizer to the tank or run the carburetor dry to prevent fuel degradation. Coat the spark plug hole with engine oil spray. Store in a cool, dry location.
• Before storm season: Verify starting operation, check oil level, ensure adequate fresh fuel supply.

Our Top Generator Picks

For the most detailed comparisons and current pricing, see our dedicated generator guides:

• Best Inverter Generators — Honda EU2200i, Yamaha EF2200iS, Champion 2000W, and more
• Best Dual Fuel Generators — Champion 3400DF, Westinghouse WGen7500DF, and more
• Best Solar Generators — Jackery, EcoFlow, Bluetti, and battery power stations
• Best Portable Generators Overall — All types compared by use case