Size against rated watts, not the number on the box
Champion lists 11,500 starting watts against 9,200 running. Westinghouse lists 12,500 peak against 9,500 running. Honda lists 2,200 W maximum against 1,800 W rated.
Fuel moves the number too, and in opposite directions depending on category. Both dual-fuel portables publish less on propane than on gasoline: Champion drops from 9,200 to 8,280 running watts, Westinghouse from 9,500 to 8,500. The two standby units publish more on LP than on natural gas — Generac is rated 19,500 W on natural gas and 22,000 W on LP, Kohler 18 kW on natural gas and 20 kW on LP. Work out which fuel you will run day to day, then read that column and no other.
The sizing method itself is unglamorous. Go through the appliances you intend to back up, read the running wattage off each nameplate or manual, and total them.
Standby and portable are not two sizes of the same thing
The gap between these categories is not capacity, it is what has to happen at 2 a.m. when the grid drops. Both standby units add remote monitoring as standard — Mobile Link Wi-Fi on the Generac, OnCue Plus on the Kohler — so you can confirm from elsewhere that the unit ran.
Portables invert all of that. Champion’s 209 lb chassis rolls on 9.5-inch solid wheels; the Westinghouse is 212.1 lb dry. Someone has to move the unit outdoors, fuel it, start it and connect loads, every single time. Westinghouse’s remote key fob shortens one step of that sequence — you can start it from a distance once it is placed — but placement, fueling and connection are still manual. The Honda, at 47.4 lb and 20.0 x 11.4 x 16.7 in, is the lightest of the five generators here.
The cost of the standby side is the installation. The Generac is 466 lb dry; Kohler publishes 555 lb shipping weight. Neither is going anywhere once sited, and neither works at all without existing natural gas service or a plumbed LP tank. If your home has neither, the standby category is closed to you regardless of how attractive the continuous-runtime argument looks.
Runtime is where multi-day outages are actually decided
A tank is a countdown. Champion publishes 10 hours at half load on a 7.7-gallon gasoline tank, the longest gasoline interval at that stated load among the portables here. Westinghouse publishes 8 hours at the same load on 6.6 gallons, or 12 hours at 25%. Honda runs 3.2 to 8.1 hours on 0.95 US gal depending on load. Multiply whichever of those applies across a week of intermittent use and the real problem surfaces: you are storing, rotating and hauling gasoline, in a period when getting more of it may be difficult.
Propane changes the shape of that problem without eliminating it.
The standby units do not have a countdown at all. Both spec sheets describe continuous running on the home’s piped natural gas or LP supply rather than an onboard tank, which is precisely the week-long scenario people buy backup power for. Kohler’s is field-convertible between natural gas and LPG.
The EcoFlow sits in its own position here. 3,600Wh of LFP storage, expandable to 25,000Wh with added modules, is stored energy rather than a production rate — it depletes and then has to be refilled.
Sound figures only compare at matched distances
Four of these publish dBA at the same measuring distance: Generac at 67 dB(A) at normal load, Kohler at 70 dB(A) in normal operation, and Champion and Westinghouse both at 74.
Honda publishes 48 to 57 dBA, which it notes varies with load and Eco Throttle setting, and the manual does not state the distance for that figure. It is the lowest published range in this set, but you cannot line it up against the 23 ft numbers and treat the difference as real. For a machine that may run for days in a neighborhood, treat the four matched figures as the only comparison the evidence supports.
When the smaller unit is genuinely enough
Where the smaller unit stops being enough is the moment a hardwired load enters the list. If the loads you want back are wired into the panel rather than plugged into an outlet, you need a transfer switch, and the evidence here shows what each unit offers: Generac’s 200A service-rated automatic switch as a separate accessory, Kohler’s RDT or RXT, the two portables’ L14-30R outlets for an owner-installed manual switch, and EcoFlow’s electrician-installed kit limited to indoor breaker panels. That single distinction, not the wattage headline, is usually what decides which half of this list a buyer belongs in.
Two things buyers ask about late
Enclosure wind ratings appear on both standby spec sheets and in none of the other documents retrieved here: Kohler at 181 mph, Generac at 150 mph (241 km/h). In a storm-prone region that is a published, checkable difference. Kohler also lists an optional cold weather package with oil, breather tube, fuel regulator and battery heaters, recommended below 32°F — an extra line item in cold climates.
Maintenance divides the same way as everything else. Both standby units are covered for 5 years, and Kohler’s runs 5 years or 2,000 hours including parts, labor and travel, with 7- and 10-year options. Generac’s programmable self-exercise runs 5 minutes weekly, bi-weekly or monthly without owner involvement. The portables carry 3-year residential warranties from Champion and Westinghouse, with oil and fuel system care left to the owner; Honda publishes a maintenance schedule with each-use checks and a first oil change at 20 hours, and the pages retrieved do not state its warranty length. EcoFlow’s 5-year coverage and 3,000+ rated cycles come with no engine maintenance of any kind, because there is no engine.
