Inverter generator vs generator: which one to buy
An inverter generator costs about twice as much per running watt as an open-frame one, and in return it is far quieter, lighter in the small sizes and clean enough for electronics.
An inverter generator costs roughly twice as much per running watt as a regular open-frame generator, around $0.32 against $0.14 to $0.15 at list price in one maker’s lineup. For that money you get power with about 3% distortion or less instead of up to 23%, a noise rating near 52 dBA instead of 68 to 72 dBA, and a 46 lb machine instead of a 105 lb one at the small end. If you run a refrigerator, a pump and a few lights, the open-frame unit is the cheaper way to get the watts. If you run laptops, a TV, an RV or a camp site, the inverter unit is usually the better pick.
“Inverter vs generator” can also mean a battery power station or a plain battery inverter against a gas generator. That is covered near the end. Most of this page compares the two kinds of gas generator.
What is different inside
An open-frame generator turns an alternator at a fixed engine speed, usually 3,600 rpm for 60 Hz power, so the engine runs at full speed whether you plug in a fridge or a phone charger. An inverter generator makes raw AC, converts it to DC, and rebuilds clean AC with electronics. Because the output no longer depends on engine speed, the engine can idle down when the load is light.
Two side effects follow from that design. The engine is quieter and burns less fuel at light loads, and the waveform is smoother. Neither one changes how many watts the machine can deliver, which is set by the engine and alternator size.
Specs side by side
The numbers below all come from one maker, Westinghouse, so they share one set of spec sheets. Brands differ in how and where they measure noise, so compare dBA within one brand’s sheets.
| Model | Running / peak watts | Noise | THD |
|---|---|---|---|
| iGen2200 (inverter) | 1,800 / 2,200 | 52 dBA | 3% or less |
| WGen3600 (open frame) | 3,600 / 4,650 | 68 dBA | 23% or less |
| WGen7500 (open frame) | 7,500 / 9,500 | 72 dBA | 23% or less |
Honda’s EU2200i, the common benchmark in the same 1,800 W class, is rated 48 dBA at a quarter load and weighs 46.5 lb. Its price at retailers is around $1,200.
| Model | List price | Per running watt | Weight |
|---|---|---|---|
| iGen2200 | $579 | $0.32 | 46.3 lb |
| WGen3600 | $510 to $529 | $0.14 to $0.15 | 105 lb |
| WGen7500 | $1,049 to $1,087 | $0.14 | 196 lb |
Prices are list prices from Westinghouse and one large dealer in October 2026. Street prices run lower on some models, and some brands cost much more, so treat the per-watt figures as a ratio and not a quote. The Honda works out near $0.67 per running watt.
Power quality
Total harmonic distortion (THD) tells you how far the output wave is from a clean sine wave. Westinghouse lists 3% or less for its inverter model and 23% or less for its open-frame ones, and many current inverter models are rated below 3%.
Laptops, TVs, phone chargers, CPAP machines and anything with a circuit board can run hot or misbehave on distorted power. If those are on your list, buy an inverter model, or check the THD figure printed for the exact open-frame model. For a medical device, ask the device maker.
Noise
The gap between 52 dBA and 68 to 72 dBA is 16 to 20 dBA, which you will hear from the next campsite or the next yard. Noise matters most where people sleep or live close together. On a job site, or for a day of outage at home, 68 dBA is tolerable.
Fuel use and runtime
Fixed engine speed shows up clearly in the runtime tables. The WGen3600 holds 4 gallons and runs 14 hours at 25% load (900 W) and 10.5 hours at 50% load (1,800 W). That is about 0.29 gallons an hour at 900 W and 0.38 gallons an hour at 1,800 W. Doubling the load raised its fuel use by only about a third.
The iGen2200 holds 1.14 gallons and runs 12 hours at 25% load (450 W), about 0.095 gallons an hour. The Honda EU2200i runs 8.1 hours at 25% load on 0.95 gallons, about 0.12 gallons an hour.
Put the figures together: at light loads the inverter unit burns about a third as much fuel per hour, for half the watts, and about two thirds of the fuel per kilowatt-hour. These are rated runtimes on a full tank at a steady load. An inverter engine speeds up as the load rises, so the saving is largest at light loads.
Weight and size
Weight scales with watts, so the real difference is where each type starts. In Westinghouse’s range the inverter model is 46.3 lb for 1,800 W. The open-frame range starts at 105 lb for 3,600 W and reaches 196 lb at 7,500 W, and those need wheels and often two people for a truck bed.
Parallel kits and 240 V
Many inverter generators can be linked in pairs. The iGen2200 takes Westinghouse’s 30 amp parallel cord, sold separately, and the Honda is parallel capable with cables sold separately. Two 1,800 W units give 3,600 W running for about $1,160 plus the cord, more than twice the list price of one 3,600 W open-frame unit, but each half is a 46 lb carry. Open-frame models like the WGen3600 and WGen7500 are not parallel capable.
Check the outlets before you buy. The iGen2200 has one 120 V duplex outlet. The WGen7500 adds a 120/240 V twist-lock outlet that Westinghouse calls transfer switch ready. Connecting it to house circuits is a job for a licensed electrician, normally under a permit.
Check your own load first
Add up the running watts of everything that will run together, then add the single highest starting figure. For example, a refrigerator (700 W running, 2,200 W starting), a sump pump (800 W running) and 420 W of lights and a TV total 1,920 W running. Add the fridge’s 2,200 W starting figure and the peak is 4,120 W.
A 1,800 W inverter generator cannot carry that load. A 3,600 W open-frame unit with 4,650 W peak can, with headroom. Run your own list through the generator size calculator, which uses the same method and adds a margin on the running watts.
Which one for which job
For camping, tailgating and RVs, take the inverter unit. Noise, weight and clean power all count, and the loads are small.
For home backup of a refrigerator, a furnace blower and a few lights, either kind works once it covers the peak. With the calculator’s presets (refrigerator 700 W running and 2,200 W starting, a 1/2 hp furnace blower 800 W and 2,350 W, and 420 W of lights and a TV) that list needs 1,920 W running and 4,270 W peak, more than a 2,200 W inverter unit gives. The open-frame is cheaper and the inverter is quieter and easier to move. Whichever you pick, run it outdoors at least 20 feet from the house with the exhaust pointed away, and look for a CO shut-off. The CPSC and Ready.gov both give that distance. Powering house circuits needs a transfer switch or interlock installed by a licensed electrician, and a permit is normally required; check with your local inspector. Power fed into house wiring without one can flow back out to the utility line and hurt or kill a line worker.
For a job site with saws, compressors and a pump, take an open-frame unit sized for the running total plus the biggest single starting figure, as above. For a laptop and a few chargers on site, a small inverter unit is enough.
Inverter or power station instead of gas
Some searchers mean a battery power station, or a plain inverter on a battery bank. A station stores energy and releases it quietly, with no exhaust, so it can run indoors when you follow the maker’s placement rules. It runs until the battery is empty, and a gas generator runs until the tank is.
Battery runtime is arithmetic. Watt-hours equal amp-hours times volts, and a 2,000 Wh power station feeding a 500 W load lasts about 2,000 x 0.85 / 500 = 3.4 hours, with 85% covering the inverter and other losses. A plain battery bank also gives only part of its rating: plan on 80% for LiFePO4 and 50% for lead-acid before the inverter loss. Convert your battery with the amp hours to watt hours calculator, and size the inverter with the inverter size calculator, which adds headroom and shows the battery current.