What Size Generator Do I Need? (2026 Wattage Calculator Guide)

The Honda EU2200i answers the "what size generator do I need" question for sensitive electronics with a definitive specification: under 3% total harmonic distortion (THD) from its inverter output. Standard conventional generators produce 20-25% THD — damaging to laptops, CPAP machines, and modern TVs over time. The EU2200i's clean sine wave output is safe for all electronics without a separate line conditioner. The 2200W running / 2500W starting capacity powers a refrigerator (700W), window AC (1,500W starting), several LED lights, and phone charging simultaneously — adequate for essential outage coverage. Eco-Throttle adjusts engine speed to match the actual load rather than running full speed constantly, reducing fuel consumption and noise when demand is low. At $980.00 it is the most expensive portable generator on this page by running wattage — the Champion 7000W at $674.00 costs $306 less and delivers 4,800W more running power. The Honda premium is specifically inverter clean power and 57-68 dBA quiet operation. For sizing: if your question is keeping essentials running (refrigerator, lights, CPAP, device charging), the EU2200i is correctly sized. If you need to run central HVAC, a well pump, or multiple circuits simultaneously, the 2200W limit requires stepping up to the Champion or Westinghouse.

The Champion 7000W answers the whole-house backup sizing question: 7000W running power handles a central AC unit (3,500-5,000W), refrigerator, well pump, and lighting simultaneously — the load set that most homeowners need to maintain livable conditions during extended outages. The 8750W starting surge handles compressor motor startups that demand momentary power spikes well above running wattage. Dual-fuel capability (gasoline or propane) is a significant advantage for extended outages. Gasoline stores for 1-2 years with stabilizer; propane stores indefinitely in sealed tanks. During a multi-day outage when gas stations are lines, propane from pre-stored tanks keeps the generator running. Cold Start Technology enables reliable starting at -20°F, addressing winter storm outage scenarios. At $674.00 it is $306 less than the Honda EU2200i at $980.00 — more watts at lower cost. The Honda's advantage is inverter clean power and quiet operation; the Champion is a conventional generator producing 74 dBA. For whole-house backup where electronics are protected by a transfer switch and noise is acceptable, the Champion is the correct size. The DuroStar at $452.47 provides 4,000W for $222 less — adequate for essential appliances but insufficient for central AC.

The Westinghouse WGen7500 delivers 7500W running / 9500W starting — the highest capacity on this page — with remote key fob start that allows the unit to be running before you walk outside during an outage. CARB compliance makes it legal for sale in California and other states with stricter emissions standards, which eliminates a purchasing barrier for those regions. The remote start key fob works at a reported 109-meter range, meaning you can start the generator from inside the house and let it warm up before connecting loads. Low oil shutdown protection prevents engine damage during unattended overnight operation — the failure mode that destroys conventional generators when oil burns low. At $1,049.00, it is $375 more than the Champion 7000W at $674.00 for 500W more running power and the remote key fob. The Champion at $674.00 covers the same whole-house loads and includes dual-fuel capability (propane) that the Westinghouse lacks. For homeowners in California or CARB-compliance states where the Champion cannot be sold, the Westinghouse is the correct choice. For all other states, the Champion provides comparable whole-house backup capability with dual-fuel flexibility at $375 less.

The DuroStar DS4000S answers the essential-appliances sizing question at the lowest cost on this page. 4000W running power handles the core outage load: a refrigerator (700W), window AC or box fans, several LED circuits, and simultaneous phone and device charging. It does not have the capacity for central HVAC — that requires 5,000W+ for the blower and compressor combined. The manual recoil start and absence of a fuel gauge are budget compromises — you track runtime manually and start with a pull cord. Four outlets provide enough connections for the essential appliance set without a transfer switch or power strip multiplication. At $452.47, it is $222 less than the Champion 7000W at $674.00 and $528 less than the Honda EU2200i at $980.00. For homeowners whose question is keeping food from spoiling and phones charged during a 2-3 day storm outage — not whole-house comfort — the DS4000S is correctly sized and the rational budget choice. Step up to the Champion if central AC, well pump, or a sump pump must run simultaneously. Step up to the Honda if clean inverter power for medical equipment or sensitive electronics is required.