Portable vs Standby Generators: Which Is Right for Your Home?
A portable generator and a home standby generator both keep the lights on, but they are different purchases. One is a machine you move, fuel and start by hand. The other is part of the house: installed outside, wired to a transfer switch and started automatically when the power fails. This guide compares the two using the manufacturer figures in our generator comparison tool, retrieved on 2 November 2026.
The short answer
- Choose portable if outages are rare or short, you want to power a few circuits, or you also need power for camping, an RV or a jobsite.
- Choose standby if you want the whole house or most of it to keep running without you doing anything, or someone at home cannot safely manage a portable unit.
Side-by-side: one standby pair and a large portable
The table lines up two air-cooled home standby generators with the largest portable in our database. The standby units are rated in kilowatts on propane and natural gas, while the portable is rated on gasoline and propane.
| Specification | GeneracGuardian 22 kW Air-Cooled Home StandbyHome standby | Kohler20RESC(L) 20 kW Home StandbyHome standby | WestinghouseWGen9500DFPortable |
|---|---|---|---|
| Price and ownership cost | |||
| Listed price (USD, estimate) | Not publishedGenerac does not list a price on the spec sheet; installed cost varies by dealer | Not publishedNot published on the spec sheet | $1,249.00Westinghouse MSRP |
| Price per rated watt (derived) | n/a | n/a | $0.13per watt, first fuel listed |
| Warranty | 5-year limited | 5-year / 2,000-hour limited (standby use) | 3 years residential, 1 year commercial |
| Maintenance | Oil change interval up to 2 years or 200 hours, per the spec sheet | Hydraulic valve lifters, so no routine valve adjustment | Not stated |
| Oil capacity | 1.9 qt including filter | 2.0 qt (1.9 L) with filter | Not stated |
| Power | |||
| Rated output by fuel |
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| Starting or surge watts | – | – | 12,500 W |
| Fuel types | Propane / Natural gas | Propane / Natural gas | Gasoline / Propane |
| Engine | Generac G-Force 1000 Series, 2-cylinder | Kohler CH1000, V-2, 4-cycle | Not stated |
| Displacement (cc) | 999 cc | 999 cc | 457 cc |
| Runtime, fuel use and running cost | |||
| Fuel tank (gal) | – | – | 6.6 gal |
| Runtime on a tank, as stated | – | – |
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| Fuel use, as stated |
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| Not stated |
| Fuel per kWh (derived) | n/a | n/a | 0.174 galgasoline at 50% load, from tank size and stated runtime |
| Fuel cost per kWh at your price (derived) | n/a | n/a | |
| Fuel cost per hour at that load (derived) | n/a | n/a | |
| Size and comfort | |||
| Weight (lb) | 445 to 466 lb | 535 lb | 211 lb |
| Dimensions | 48 x 25 x 29 in | 48 x 26.2 x 28.9 in (1216 x 665 x 733 mm) | Not stated |
| Noise (as stated) | 67 dB(A) at 23 ft, normal load; 55 to 57 dB(A) in Quiet-Test exercise mode | 64 dB(A) during weekly exercise; 69 dB(A) at full speed (7 m, no load) | 74 dBA |
| Starting method | Automatic (on utility failure) | Automatic (on utility failure) | Electric, Remote, Recoil |
| Features | |||
| Inverter output | No | No | No |
| Total harmonic distortion | Less than 5% | Not stated | Not stated |
| Automatic voltage regulation (AVR) | Yes | Yes | Not stated |
| CO sensor shutdown | – | – | No |
| Transfer switch ready | Yes | Yes | Yes |
| Transfer switch detail | 200 amp service-rated automatic transfer switch available | Model RXT automatic transfer switch available (20RESCL packages) | – |
| Parallel capable | – | – | No |
| Outlets and connections | Hard-wired to the home; 120/240 V single phase | Hard-wired to the home; 120/240 V single phase at 60 Hz | Two 5-20R duplex, L14-30R, 14-50R, transfer switch ready |
| Fit | |||
| Suited to | Whole-house power, Home backup | Whole-house power, Home backup | Home backup, Construction and jobsite, Heavy duty |
| Also worth knowing | Wi-Fi monitoring standard; listed for installation as close as 18 in to a structure; enclosure rated for winds to 150 mph | Polymer base needs no concrete pad; OnCue Plus remote monitoring included; field-convertible between natural gas and propane | Transfer switch ready (ST switch) |
| Honest take | |||
| Advantages |
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| Drawbacks |
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| Source | |||
| Where the figures come from | Generac Guardian 20/22/24 kW spec sheet (PDF)Retrieved 2026-11-02 | Kohler 20RESC(L) spec sheet G4-246 (PDF)Retrieved 2026-11-02 | Westinghouse product pageRetrieved 2026-11-02 |
How they differ
Power
The Generac Guardian 22 kW is rated at 22,000 W on propane and 19,500 W on natural gas. The Kohler 20RESC(L) is rated at 20,000 W on propane and 18,000 W on natural gas. The largest portable in the table, the Westinghouse WGen9500DF, is rated at 9,500 W on gasoline. A standby unit has roughly twice that capacity, which is why it can carry central air conditioning and several large loads at once. Size your own needs with the generator load calculator before deciding.
Fuel
Standby generators run on a pipeline natural gas supply or on propane, so there is nothing to refill during an outage if you are on a gas line. Portables burn gasoline or, on dual-fuel models, propane, and you carry and store that fuel yourself. Our guide to generator fuels covers storage and shelf life. For fuel burn, the Generac Guardian 22 kW uses 142 cubic feet of propane per hour at full load, which Generac states as 3.90 gal/h, and the Kohler uses 136 cfh of propane at full load.
Starting and transfer
Standby units start on their own and switch the house over through an automatic transfer switch. Generac offers a 200 amp service-rated switch for the Guardian and Kohler offers its RXT automatic transfer switch. A portable needs you to start it, and it needs a safe connection to the house. Read how to connect a generator to a house before you improvise one, because a wrong connection can back-feed the grid and injure line workers.
Noise and placement
Generac states 67 dB(A) at 23 ft at normal load for the Guardian and 55 to 57 dB(A) in its weekly exercise mode. Kohler states 64 dB(A) during exercise and 69 dB(A) at full speed, measured at 7 m. The WGen9500DF is listed at 74 dBA. A portable has to sit outdoors and away from windows and doors, every time you use it, because of carbon monoxide. A standby unit has a fixed, code-compliant location.
Cost
Neither Generac nor Kohler publishes a price on the spec sheets we reviewed, because installation, the transfer switch, the gas line and local permits all change the total. The Westinghouse WGen9500DF is listed at $1,249 MSRP. For any standby purchase, get written quotes for the installed system and compare those, not the unit price alone. Include yearly service in your running cost.
Warranty
Generac states a 5-year limited warranty on the Guardian. Kohler states a 5-year or 2,000-hour limited warranty for standby use. Check the portable warranty on the maker’s page, because the terms differ by brand and by whether you use the unit commercially.
Which fits your home
| Your situation | Better fit | Why |
|---|---|---|
| A few outages a year, mostly under a day | Portable | You only need the fridge, lights and a few essentials, and the cost is a fraction of a standby system. |
| Long outages, storms or well-pump and furnace loads | Standby | It runs on its own and has the capacity for large loads. |
| You also camp, tailgate or work on sites | Portable | A standby unit cannot leave the house. |
| Medical equipment at home | Standby, or a battery backup as a first layer | Automatic transfer removes the need for someone to act during an outage. Talk to the equipment provider. |
| You rent or may move | Portable | A standby system stays with the property. |
What we could not verify
We do not quote installed prices, because none of the makers publish them. The Kohler spec sheet is dated January 2019, so confirm the current Kohler (Rehlko) listing. The Generac sheet gives weights of 445 to 466 lb across its 22 kW variants, so check the model number you are buying.
Related guides
- Generator comparison tool
- Best generators for home backup
- Generator comparison by wattage
- Generator size calculator
Frequently asked questions
Is a standby generator worth it?
It is worth it when outages are long or frequent, or when nobody at home can run a portable safely. For short, rare outages a portable generator and a few extension cords or a transfer switch cover most needs for less money.
Can a portable generator power a whole house?
A large portable can power many circuits through a transfer switch, but it will not match a 20 kW class standby generator. Add up the running watts of what you need with the load calculator to see where you land.
Do standby generators need a gas line?
The units we compare run on natural gas or propane. Natural gas needs a utility line, while propane uses a tank on the property. A licensed installer sizes the fuel line for full load.
