Which one runs a refrigerator or a space heater?

The Generac. Its 2500 W continuous output handles a typical fridge and most space heaters. The OSAK's 800 W continuous will not start a standard 1500 W heater reliably.

The OSAK states 58 dB in ECO mode. Generac markets the GP3300i as a quiet inverter but gives no usable decibel figure, so the OSAK has the only verifiable number.

Is the Generac worth $289 more?

Yes if you need more than 800 W, CO shutdown or easier carrying. No if you only charge devices and run lights, where the OSAK's price and runtime win.

Which lasts longer on a tank?

The OSAK, with a 2.3 gal tank and about 17 hours at 25% load. The Generac runs about 4.5 hours at 50% load on 1.06 gal.

Can I move them easily?

The Generac at 59.5 lb is far easier to lift and carry. The OSAK is 97 lb and relies on its wheels and foldable handle.

Do either protect against carbon monoxide?

Only the Generac, which has COsense automatic shutoff. The OSAK lists no CO sensor, so never run it indoors or in a garage.

OSAK APR 4500W Inverter Generator vs Generac GP3300i Inverter Generator

Buy the Generac GP3300i if you need real usable power, CO safety and a lighter unit. Buy the OSAK only if the lowest price is the hard limit and your loads are small. As of November 5, 2026, the OSAK is $459.99 at Tractor Supply Company and the Generac is $749.00 at Nishna Valley Cycle, a $289 gap.

Today the OSAK APR 4500W Inverter Generator costs $289.01 less at its best price.

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