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What is the best portable generator? The best fit is the unit whose running watts cover the loads you plan to run at the same time, whose outlets match those loads, and whose run time and noise level fit where you will use it. A campsite at dusk with a dead phone, an RV parked far from a hookup, or a home in an outage with food to keep cold all call for the same thing: power that starts when you need it and keeps going until the job is done. This guide walks through the figures the listings state, so you can match a unit to your loads instead of guessing from the box.
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The quick answer
Start with running watts, not peak watts. Peak watts cover the short spike when a motor starts, while running watts cover the load while it runs. The listings in this guide show the spread: the Oxseryn open-frame (on Amazon) unit lists 4400 peak watts and 3400 running watts, the PowerSmart inverter (on Amazon) lists 3800 starting watts and 3200 running watts, and the smaller Oxseryn inverter (on Amazon) lists 2800 peak watts and 2000 running watts. For a large home load, the Westinghouse dual-fuel (on Amazon) unit lists 12500 peak watts and 9500 running watts on gasoline, and 11200 peak watts and 8500 running watts on propane. Pick the smallest unit whose running watts still cover everything you plan to run at the same time, then check outlets, run time and noise.
Step 1: Add up the running watts
List every load you plan to run at the same time, then add the running watts from each load’s label. A motor pulls more at startup than while running, so peak watts must cover that spike while running watts cover the steady draw. A watt meter between the load and the outlet measures real draw over time, which beats guessing from the box. As a yardstick, the listings here range from 2000 running watts on the small Oxseryn inverter to 9500 running watts on gasoline for the Westinghouse, with 3200 and 3400 running watts in the middle.
| Unit | Peak watts | Running watts | Run time | Noise at 23 ft |
|---|---|---|---|---|
| Oxseryn open-frame generator | 4400 | 3400 | 14 hours at 25% load | Under 72 dBA |
| Westinghouse dual-fuel generator | 12500 on gasoline, 11200 on propane | 9500 on gasoline, 8500 on propane | 12 hours | Not stated |
| PowerSmart inverter generator | 3800 starting watts | 3200 | Not stated | 59 dBA |
| Oxseryn inverter generator | 2800 | 2000 | 9 hours at 25% load | Under 58 dBA |
Run times are as the listings state them. The Westinghouse listing states up to 12 hours of run time, and the two Oxseryn listings state run time at 25% load with ECO mode.
Step 2: Match the outlets
Check the outlets before you buy, because no adapter adds a socket the unit lacks. Look for two 120V AC ports and a 12V DC port on the Oxseryn units, a 120V 20A duplex and a 120V 30A twist-lock plus dual 5V 2.1A USB ports on the PowerSmart, and on the Westinghouse two GFCI 120V 20A household receptacles, a 120V 30A receptacle and a 120/240V 50A RV receptacle. The Oxseryn 2800 adds a USB port and a Type-C port, which suit phones, laptops and cameras. Match each load to a socket of the same volts and amps, and leave a spare socket for the next load you add.
Step 3: Check run time and fuel
Run time is the hours a tank gives at the load the listing states. The Oxseryn open-frame unit runs for up to 14 hours at 25% load on a 2 gallon fuel tank with ECO mode, and the smaller Oxseryn inverter runs for up to 9 hours at 25% load on a 1.1 gallon tank. The Westinghouse runs for up to 12 hours on a full tank. The PowerSmart listing states no run time, so treat that figure as not stated rather than guessing. ECO mode trims the engine speed when the load drops, which is why the Oxseryn listings quote run time at 25% load.
Step 4: Weigh noise and weight
Noise is stated in dBA at 23 feet, so the figures compare directly. The PowerSmart lists 59 dBA from 23 feet away, the small Oxseryn inverter lists under 58 dBA from 23 feet away, and the open-frame Oxseryn lists under 72 dBA from 23 feet away. The Westinghouse listing states no noise figure. Weight matters when you carry the unit: the open-frame Oxseryn weighs 56 lbs and the PowerSmart weighs 47 lbs. The small Oxseryn listing gives 39 lbs in the title and 40 lbs in the bullets, so treat its weight as stated with a conflict and check the listing before you carry it far. See the best gas generators for camping for units built around campsite use.
What is the best portable generator for home backup?
For home backup, size rules the choice. The Westinghouse lists 9500 running watts on gasoline and 8500 running watts on propane, with up to 12 hours of run time, which suits a fridge, lights and a phone charger running together through an outage. Its outlets include a 120/240V 50A RV receptacle and a 120V 30A receptacle. If a unit connects to home wiring, a licensed electrician should install it. Run a fuel generator outdoors only, far from doors and windows, because of carbon monoxide. For a quieter backup that needs no fuel, see the best portable power stations for home backup.
Ways to make the fuel last
- Run ECO mode when the load allows it; the Oxseryn listings tie their run time figures to ECO mode at 25% load.
- Switch off loads you are not using.
- Keep the tank full before an outage.
- Match the generator to the load; the listings here run from 2000 to 9500 running watts.
FAQ: power away from the grid
What size portable generator do I need?
Add the running watts of everything you plan to run at the same time, then pick a unit whose running watts cover that total, with peak watts to spare for motor startup. The listings in this guide range from 2000 running watts to 9500 running watts on gasoline, so the range covers a campsite load and a home backup load alike.
Are inverter generators quieter than open-frame generators?
On the figures the listings state, yes. The PowerSmart inverter lists 59 dBA and the small Oxseryn inverter lists under 58 dBA, each from 23 feet away, while the open-frame Oxseryn lists under 72 dBA from 23 feet away. See the benefits of an inverter generator for more on clean power.
How long will a portable generator run on a tank of fuel?
It depends on the tank and the load. The Oxseryn open-frame unit runs for up to 14 hours at 25% load on a 2 gallon tank, the small Oxseryn inverter runs for up to 9 hours at 25% load on a 1.1 gallon tank, and the Westinghouse runs for up to 12 hours on a full tank. The PowerSmart listing states no run time.
Can I run a portable generator indoors?
No. The PowerSmart listing states the rule plainly: never use a generator indoors or in partially enclosed areas, and only use it outdoors.
What does THD under 3% mean?
THD is the distortion in the power the generator puts out, and the PowerSmart and the small Oxseryn inverter list THD under 3%, which the listings call clean power for laptops, mobile phones and tablets. If you plan to run sensitive electronics, look for that figure in the listing.
Related solar guides
See the best gas generators for camping, the best portable power stations for home backup, the benefits of an inverter generator and every Camping and Emergency Gear guide.
