Generac generator sizes explained: the 14kW, 18kW, 22kW, 24kW and 26kW

Generac generator sizes explained in one place: this guide lists the five Guardian home standby sizes we install, from the 14kW to the 26kW, with the propane and natural gas ratings, the engine and the weight Generac publishes for each. Every figure comes from Generac's own product pages, linked below, and Generac notes that specifications are subject to change without notice. We sell and install Generac home standby and commercial generators.

Each size also has its own page on our site: the Generac 14kW generator, the 18kW, the 22kW, the 24kW and the 26kW. All five are listed together on our Generac generators page.

What sizes does the Generac Guardian home standby line come in?

The Guardian sizes we install are the 14kW, 18kW, 22kW, 24kW and 26kW. Each one runs on propane or natural gas, and Generac publishes a separate rating for each fuel. The number in each name matches its propane rating, so on a natural gas house the figure to check is the lower natural gas rating.

Model numbers help when you compare quotes or read a spec sheet. Generac lists the 14kW as base model G007223, the 18kW as G007226, the 22kW as G007043, the 24kW as G007209 and the 26kW as G007290. The 22kW model number is a package that includes a transfer switch, which is covered further down.

How many watts does each Generac size put out on propane and natural gas?

Generac rates the 14kW at 14,000 watts on both fuels, the 18kW at 18,000 watts on propane and 17,000 on natural gas, and the 22kW at 22,000 and 19,500. The 24kW is rated 24,000 and 21,000, and the 26kW 26,000 and 22,500. Those are Generac's published figures, read from each product page.

• Generac Guardian 14kW: 14,000 watts on propane, 14,000 watts on natural gas, G-Force 800 engine, 60 amp main line circuit breaker, 385 lb.
• Generac Guardian 18kW: 18,000 watts on propane, 17,000 watts on natural gas, G-Force 800 engine, 80 amp main line circuit breaker, 420 lb.
• Generac Guardian 22kW: 22,000 watts on propane, 19,500 watts on natural gas, G-Force 1000 engine, 466 lb.
• Generac Guardian 24kW: 24,000 watts on propane, 21,000 watts on natural gas, G-Force 1000 engine, 455 lb.
• Generac Guardian 26kW: 26,000 watts on propane, 22,500 watts on natural gas, G-Force 1000 engine, 110 amp main line circuit breaker, 518 lb.

The sources are Generac's own pages: the 14kW product page, the 18kW product page, the 22kW product page, the 24kW product page and the 26kW product page. Each page links a spec sheet, such as the spec sheet covering the 14kW and 18kW and the 26kW spec sheet. Where a page did not state a figure, such as the main breaker on the 22kW and 24kW, we leave it out.

Why does a Generac put out less power on natural gas?

Natural gas carries less energy than propane for the same volume, so the same engine makes less power on it. Every size above the 14kW has a lower natural gas rating, and the gap grows with the size: 1,000 watts on the 18kW, 2,500 on the 22kW, 3,000 on the 24kW and 3,500 on the 26kW.

On paper the sizes look evenly spaced. On natural gas they sit closer together: 14,000, 17,000, 19,500, 21,000 and 22,500 watts. A natural gas house choosing between the 22kW and the 24kW is comparing 19,500 watts with 21,000, a difference of 1,500 watts, not the 2,000 the names suggest. Many homes inside San Antonio are on natural gas from the street, so this comparison comes up often.

Which fuel suits your house is covered in our guide to natural gas vs propane standby generators.

Which engine does each Generac size use?

Generac lists the G-Force 800 engine on the 14kW and the 18kW, and the G-Force 1000 engine on the 22kW, 24kW and 26kW. Generac publishes the weights too: 385 lb for the 14kW, 420 lb for the 18kW, 466 lb for the 22kW, 455 lb for the 24kW and 518 lb for the 26kW.

Weight matters for placement. The unit sits on a pad, and the route from the truck to the pad has to take it, whether that is through a side yard, a gate or past a fence. We look at that route at the sizing visit, along with the setbacks from windows, doors and the property line that decide where the unit can sit.

What does each Generac size usually suit?

Size follows the load list, not the size of the house. As a starting point, the 14kW usually suits essential circuits, the 18kW often carries one central air system with the essentials, and the 22kW covers most of a typical house with load management. The 24kW and 26kW suit larger homes and two air systems.

• 14kW: the refrigerator, lights, outlets, the internet router, a well or sump pump, and sometimes one smaller air conditioner.
• 18kW: often the first size that carries one central air system alongside the essentials.
• 22kW: most of a typical house, including central air, when the largest loads are managed.
• 24kW: larger homes, two air conditioning systems, or natural gas houses that are tight on a 22kW.
• 26kW: two central air systems are the usual reason, with load management letting both share the generator in turn.

Each size has its own guide: what a Generac 14kW can run, the 18kW, the 22kW, the 24kW and the 26kW.

Those are starting points, not a promise for your house. A smaller home with a large air conditioner can need more than a bigger home with an efficient one. The deciding number is everything that runs at the same time, plus the extra current a compressor draws as it starts.

How do I choose between two Generac sizes?

Choose the smallest size that carries everything you want running at the same moment, on the fuel your house actually has, including the starting surge of the air conditioner. If your list sits right at the line of the smaller size, a soft starter or load management can often keep it there instead of moving up a size.

Write the list before the sizing visit: the rooms you live in during an outage, the appliances you would miss first, and anything a person in the house depends on, such as medical equipment or a home office. If you plan to add a pool, an electric vehicle charger or a second air system later, say so, because the generator should be sized for the house it will serve.

We cover the work from home case in standby generator for a home office, and the room by room method in sizing a Generac for a Texas home.

Does a Generac generator come with a transfer switch?

Generac sells the 22kW in a package with a 200 amp, NEMA 3R smart switch for up to whole house protection, under model G007043. For the other sizes, the transfer switch is chosen to match your service and your load list: a whole house switch, an essential circuit switch, or load management for large loads.

The switch types are compared in our guide to generator transfer switch types. Whether the packaged switch suits your service, or an essential circuit switch fits better, is part of the sizing visit.

What warranty does Generac publish for these sizes?

Each of the five product pages shows Generac's 5 Year Limited Warranty. That is the wording Generac publishes, and the written warranty terms for the exact model are Generac's, so read them before you buy. What an installer promises on its own workmanship is a separate question, and the answer should be in writing.

More on reading the terms is in our Generac warranty basics post.

How much does it cost to install a Generac generator?

The installed price is the unit plus the transfer switch, the wiring, the placement and the gas line, and each part changes from house to house, so we do not publish one number for it. You get a written price after the free sizing visit, with the gas line quoted separately as a licensed plumber's work.

Book the free Generac sizing visit and a licensed electrician lists the loads with you, checks the panel, the service and the gas meter, and writes the price. What moves each part is in our Generac generator cost guide.

Gas line and gas connection are not included. That is a licensed plumber's work and we quote it separately. We schedule the plumber with the electrical work so the unit is ready to run on the day it is finished.

Do I need a permit for a Generac generator in San Antonio?

Inside San Antonio, the City's electrical permit application covers generators. Outside the city, we confirm what that city requires before we give you the price. The gas line is the plumber's side of the job and is handled with the plumber's quote.

The install itself, from setting the unit to the start up test under load, is on our Generac generator installation page. To ask about a size before you book, use our contact page.