Generac power generators come in more types than most people realize, and picking the right type matters more than picking the right model. A small inverter, a tri fuel portable and a home standby system all carry the Generac name. They solve completely different problems.
This guide lays out the whole range by type. You will see every current Generac portable with its real numbers, the home standby sizes from 10 kW upward, and a simple way to decide which kind of generator fits your home, your RV or your work.
All figures come from the spec tables on Generac’s website or from current Amazon listings. We have not tested these generators ourselves.
Generac generators at a glance
From a 48-pound inverter to a 150 kW standby unit
Lineup data comes from the product pages on Generac’s official website, checked in October 2026.
Quick answer
Generac sells five main kinds of generator. Open-frame portables give the most watts for the money. Inverters are quiet and safe for electronics. Dual fuel and tri fuel portables add propane or natural gas. One diesel portable suits job sites. Home standby generators, from 10 to 28 kW air-cooled and up to 150 kW in larger models, are installed permanently and start by themselves. Choose the type first, then the size.
How we put this guide together
We have not tested these generators. Portable and standby model lists, wattages, run times and weights come from the product pages and spec tables on Generac’s official website. Air-cooled standby ratings come from Generac dealer documentation. Product box details come from current Amazon listings. Where Generac’s own pages disagreed with each other, we say so or leave the figure out. We do not show prices or star ratings.
In this guide
- The Main Types of Generac Generator
- Generac Open-Frame Portable Generators
- Generac Inverter Generators
- Dual Fuel, Tri Fuel and Diesel Portables
- Generac Home Standby Generators
- Portable Power Stations
- How to Read a Generac Model Name
- Which Type of Generac Do You Need?
- Four Generac Picks, One From Each Family
- Staying Safe With Any Generac
- Common Mistakes When Choosing a Generac (and the Fix)
- Pro Tips for Picking From the Range
- Real-Life Scenarios: Which Generac Type?
- Generac Power Generators: FAQ
- Your Generac Type Checklist
The Main Types of Generac Generator
| Type | Size range | Fuel | Starts | Best for |
|---|---|---|---|---|
| Open-frame portable | 3,600 to 18,000 running watts | Gasoline | Pull cord or electric | Home backup and job sites on a budget |
| Portable inverter | 2,200 to 3,900 running watts | Gasoline, or gasoline and propane | Pull cord or electric | Camping, RVs and electronics |
| Dual fuel and tri fuel portable | 7,500 to 9,500 running watts | Gasoline, propane, natural gas | Electric | Home backup with a second fuel |
| Diesel portable | 5,000 running watts | Diesel | Electric | Job sites and long running |
| Home standby, air-cooled | 10 to 28 kW | Natural gas or propane | Automatic | Whole-home backup for most houses |
| Home standby, larger models | 22 to 150 kW | Natural gas, propane or diesel | Automatic | Large homes and small businesses |
Key insight: the big question is not “which Generac?” It is “do I want to start it myself, or should it start by itself?” That one answer splits the range in two.
Generac Open-Frame Portable Generators
These are the classic generators on a steel frame with wheels. Generac sells them in its GP series. They are louder than inverters, but they deliver the most power for the price and several have 240-volt outlets for home backup.
| Model | Running watts | Starting watts | Run time | Fuel tank | Weight | Start |
|---|---|---|---|---|---|---|
| GP3600 | 3,600 | 4,500 | 9.3 hours | 3.7 gal | 105 lb | Pull cord |
| GP5500E, fuel injected | 5,500 | 6,875 | 10.5 hours | 5.4 gal | 172 lb | Electric |
| GP6500 | 6,500 | 8,125 | 10.5 to 11.5 hours | 7.9 gal | 172 lb | Pull cord |
| GP8000E | 8,000 | 10,000 | 10 hours | 7.9 gal | 198 lb | Electric |
| GP15500EFI | 15,500 | 19,300 | 11 hours | 14.2 gal | 420 lb | Electric |
| GP18000EFI | 18,000 | 22,500 | 9 hours | 14.2 gal | 443 lb | Electric |
Several of these come in more than one version. The GP6500 is sold with a pull cord or with electric start, and with or without an extension cord in the box.
Features that run through the GP series include:
- PowerRush, which Generac says delivers over 40% more starting capacity on the models that list it.
- COsense, a carbon monoxide sensor that shuts the generator down if CO builds up.
- Low-oil shutdown to protect the engine.
- An hour meter so you know when service is due.
- A 1.25-inch steel-tube cradle, fold-down handle and never-flat wheels.
The two giants
The GP15500EFI and GP18000EFI are in a class of their own. Each uses an 816 cc fuel-injected engine and a 14.2-gallon tank, and each weighs more than 400 pounds. Generac describes its largest portables as among the largest available. They suit people who want standby-size power without a permanent installation.
Generac Inverter Generators
An inverter generator makes smoother electricity than an open-frame model, and its engine slows down when demand is light. That makes it quieter, lighter and kinder to electronics. Generac’s inverters top out at 3,900 running watts.
| Model | Running watts | Starting watts | Fuel | Run time | Weight | Start |
|---|---|---|---|---|---|---|
| GP2500i | 2,200 | 2,500 | Gasoline | 4.5 to 5.5 hours | 48 lb | Pull cord |
| GP3300i | 2,500 | 3,300 | Gasoline | 4.5 hours | 61 lb | Pull cord |
| 3500i | 3,000 | Not listed | Gasoline | 8.9 hours | 109 lb | Electric |
| iQ3800 Dual Fuel | 3,000 | 3,800 | Gasoline or propane | 13 hours | 107 lb | Electric |
| iQ5200 Dual Fuel | 3,900 | 5,200 | Gasoline or propane | 9 hours | 111 lb | Electric |
A few points help you read that table.
- The model number is the starting watts. A GP3300i starts at 3,300 watts and runs at 2,500.
- The iQ models add propane. The Amazon listing for the iQ3800 gives 3,000 running watts on gasoline and 2,700 on propane.
- Clean power is the point. The listings state less than 3% total harmonic distortion, which is safe for laptops and medical devices.
- Two can work as one. Most of these inverters are parallel ready, with a kit sold separately.
Our guide to inverter vs conventional generators explains the technology.
Dual Fuel, Tri Fuel and Diesel Portables
Fuel choice is where Generac’s portable range has grown most.
| Model | Fuels | Running watts on gasoline or diesel | On propane | On natural gas | Weight |
|---|---|---|---|---|---|
| GP7500E Dual Fuel | Gasoline, propane | 7,500 | 6,800 | Not available | 204 lb |
| GP9500E Tri Fuel | Gasoline, propane, natural gas | 9,500 | 8,550 | 7,000 | 219 lb |
| XD5000E | Diesel | 5,000 | Not available | Not available | 252 lb |
The lesson in that table is the same for every brand: a generator makes less power on propane, and less again on natural gas. Size it for the fuel you will really use.
- The GP7500E Dual Fuel uses a 420 cc engine and a dial to switch between gasoline and propane.
- The GP9500E Tri Fuel has a 500 cc engine and both 30-amp and 50-amp 240-volt outlets. On natural gas it can run for as long as the gas supply lasts.
- The XD5000E is the odd one out. It has a Yanmar diesel engine, a 12-gallon tank and a listed run time of 32.4 hours at half load. Generac says the battery and wheel kit are sold separately.
For more on choosing a fuel, read our guides to dual-fuel generators and diesel vs gas generators.
Generac Home Standby Generators
This is the product Generac is best known for. A home standby generator sits outside on a pad, connects to your natural gas line or propane tank, and starts automatically when the power fails. Generac says it begins supplying power within seconds, whether you are home or not.
The air-cooled models cover most houses.
| Size | Engine | Rating on LP | Rating on NG |
|---|---|---|---|
| 10 kW | 459 cc | 10 kW | 9 kW |
| 14 kW | 817 cc V-twin | 14 kW | 14 kW |
| 18 kW | 817 cc V-twin | 18 kW | 17 kW |
| 22 kW | 997 cc V-twin | 22 kW | 21 kW |
| 24 kW | 997 cc V-twin | 24 kW | 22.5 kW |
| 26 kW | 997 cc V-twin | 26 kW | 24 kW |
| 28 kW | 997 cc V-twin | 28 kW | 25 kW |
Generac’s website shows two generations side by side. The newer models are labeled “Cellular” and the Guardian Series models are labeled “WiFi Enabled”. Each size is sold on its own or packaged with a transfer switch. There is also a 20 kW three-phase model.
Generac’s own guidance on sizing is simple. It says smaller homes may need a 10 to 18 kW unit, while larger homes with several air conditioners may need 22 to 28 kW. It adds that these generators average 65 to 67 decibels, which it compares to a central air conditioner.
Larger standby generators
Above the air-cooled range, Generac lists bigger machines for large homes and small businesses.
- Gaseous models at 22, 25, 27, 30, 32, 40, 48, 60, 80, 100, 130 and 150 kW.
- Single-phase and three-phase versions of many sizes.
- Diesel standby models at 15, 20, 30, 48 and 50 kW, some with extended fuel tanks.
Generac’s support site refers to its liquid-cooled range as running up to 150 kW, and warns that not every dealer is trained to service those units. If you need one, start with the dealer. Our guide to whole-house generators covers sizing and installation.
Portable Power Stations
Generac also lists two portable power stations, the 1000 and the 2000. These are battery units, not engine generators. They weigh 29 and 43 pounds. They suit phones, laptops and small devices, and they are a different tool from anything else in this guide.
How to Read a Generac Model Name
Generac’s product names pack in a lot of codes. Once you know them, the listings get much easier.
| Code | Meaning | Example |
|---|---|---|
| GP | Generac’s main portable series | GP6500 |
| iQ | Enclosed inverter series | iQ5200 |
| i at the end | Inverter | GP3300i |
| E at the end | Electric start | GP8000E |
| DF | Dual Fuel: gasoline or propane | iQ3800 DF |
| TF | Tri Fuel: gasoline, propane or natural gas | GP9500E TF |
| EFI | Electronic fuel injection | GP5500E EFI |
| XD | Diesel | XD5000E |
| 49ST | A version for 49 states, not California | iQ3800 49ST |
| 50ST | A version for all 50 states, including California | iQ5200 50ST |
| kW | Kilowatts, used for standby units. One kW is 1,000 watts. | 22kW |
On portables, remember that Amazon titles often lead with starting watts. The generator sold as a “12,500 watt tri fuel” is the GP9500E, which runs at 9,500 watts.
Which Type of Generac Do You Need?
Work through these questions in order.
- Should it start by itself? If yes, you need a home standby generator. If you are happy to wheel it out and start it, a portable will do.
- What must it run? Add up the running watts and the largest starting surge. Our Generator Size Calculator does the sums.
- Do you need 240 volts? Well pumps, some furnaces and central air need it. Small inverters are 120 volts only.
- Which fuel do you have? A natural gas line or a big propane tank points to standby or tri fuel. Otherwise gasoline or dual fuel.
- How much noise can you live with? For campsites and close neighbors, choose an inverter.
- Who will install it? A standby unit needs a dealer or licensed trades. A portable used with a transfer switch needs an electrician.
| Your need | Generac type | Models to look at |
|---|---|---|
| Camping and tailgating | Small inverter | GP2500i, GP3300i |
| An RV with one air conditioner | Dual fuel inverter | iQ3800 Dual Fuel, iQ5200 Dual Fuel |
| Home essentials on a budget | Open-frame portable | GP5500E, GP6500 |
| Most of a home, with a fuel backup | Dual or tri fuel portable | GP7500E Dual Fuel, GP9500E Tri Fuel |
| Job sites and long running | Diesel portable | XD5000E |
| Automatic backup for a typical house | Air-cooled home standby | 18 to 24 kW |
| Automatic backup for a large house | Larger air-cooled or liquid-cooled standby | 26 kW and up |
Still deciding between the two big families? Read portable vs standby generators.
Four Generac Picks, One From Each Family
Each of these had an active Amazon listing when we checked in October 2026.
Inverter family
Generac GP3300i Portable Inverter Generator (3,300 Starting Watts)
A compact gasoline inverter that one person can carry. The listing says its starting surge can handle a refrigerator or an RV air conditioner.
- Running watts2,500 W
- Starting watts3,300 W
- Power qualityLess than 3% THD
- Run timeUp to 7 hours at 25% load
- Weight59.5 lb
- Warranty3-year residential limited
- Why it works: PowerRush is listed as giving 50% more starting capacity, which helps with motor loads that would trip a smaller inverter.
- Who it is best for: campers, RV owners and homeowners who want quiet power for a few essentials.
- What it solves: dirty power. TruePower technology makes it safe for laptops, tablets and CPAP machines.
- Handy extras: two 120-volt 20-amp outlets, a 120-volt 30-amp twist-lock outlet, two USB ports, COsense and a parallel-ready design.
- Keep in mind: the tank holds just over a gallon, so run time at half load is about 4.5 hours. It has a pull cord and runs on gasoline only.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Dual fuel inverter family
Generac iQ3800 Dual Fuel Portable Inverter Generator (3,800 Starting Watts)
An enclosed inverter on wheels that runs on gasoline or propane. It is the quieter, cleaner way to power an RV or a home’s essentials.
- On gasoline3,000 running, 3,800 peak
- On propane2,700 running, 3,400 peak
- Engine212 cc OHV
- Run timeUp to 20 hours at 25% load
- Weight107 lb
- Emissions49-state version
- Why it works: Economy Mode stretches the run time and lowers noise when demand is light.
- Who it is best for: RV owners and campers who already carry propane, and homeowners who want a quiet backup.
- What it solves: stale gasoline. Propane stores for years, so the generator is ready after a long rest.
- Handy extras: push-button start with a recoil backup, four GFCI outlets, a 30-amp locking outlet, USB ports and a 4-foot propane hose.
- Keep in mind: this listing is the 49-state version, so California buyers need the 50-state model. Every outlet is 120 volts.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Tri fuel family
Generac GP9500E Tri-Fuel Portable Generator (12,500 Starting Watts)
The big multi-fuel portable. It runs on gasoline, propane or natural gas and has the outlets to feed a home through a transfer switch.
- Running watts9,500 W
- Starting watts12,500 W
- Engine500 cc OHV
- Run timeUp to 9.5 hours at 50% load
- 240-volt outlets30A L14-30R and 50A 14-50R
- Weight219 lb
- Why it works: a simple dial changes fuel, and on a natural gas line the run time is limited only by the supply.
- Who it is best for: homeowners who want near-standby power but are happy to start it themselves.
- What it solves: fuel shortages in a long outage. If gasoline runs out, you still have two other fuels.
- Handy extras: push-button electric start with a battery, COsense, an hour meter and a 3-year residential limited warranty.
- Keep in mind: output is lower on propane and natural gas. Generac’s fuel-injected version of this model lists 8,550 and 7,000 running watts on those fuels. It weighs 219 pounds.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Home standby family
Generac 28kW Whole Home Generator with Transfer Switch and Cellular Capability
The largest air-cooled Generac home standby generator, sold with a transfer switch. It starts automatically and reports to the Mobile Link app.
- Size28 kW
- TypeAir-cooled home standby
- Transfer switchIncluded
- MonitoringBuilt-in cellular
- Weight524 lb
- Warranty5-year limited
- Why it works: it restores power with nobody at home, and it never needs refueling by hand.
- Who it is best for: large homes with several air conditioners or many electric appliances.
- What it solves: long outages. It runs from your natural gas line or propane tank for as long as fuel is available.
- Handy extras: oil level sensors, improved cold starting and a sloped roof with a rear air intake to keep snow and ice out.
- Keep in mind: it weighs 524 pounds and needs professional gas and electrical installation with permits. The listing says remote monitoring requires a Mobile Link subscription.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Want an open-frame gasoline model? The Generac GP8000E lists 8,000 running watts and 10,000 starting watts with electric start.
Staying Safe With Any Generac
The type changes, but the safety rules do not.
Carbon monoxide and backfeeding
Run a portable generator outdoors only. Generac’s FAQ says never to run one indoors, in a garage or in an enclosed area, and to keep it away from doors and windows. COsense is a backup, so fit carbon monoxide alarms indoors too. Never plug a generator into a wall outlet. To power your home’s circuits, use a transfer switch fitted by an electrician. A standby generator must be installed by qualified trades, following the manual and local codes.
Read our generator safety tips and the guide on connecting a generator to your house.
Common Mistakes When Choosing a Generac (and the Fix)
Pro Tips for Picking From the Range
- Use Generac’s finders. Its website has a portable product finder and a standby solution finder.
- Compare versions of the same model. Electric start, a cord in the box or 50-state approval can change the name and the price.
- Check the oil schedule. Generac’s portable FAQ says to change the oil after the first 20 to 30 hours, then every 100 hours.
- Look at run time and tank size together. A long run time with a small tank means a frugal engine. A long run time with a huge tank just means a huge tank.
- Think about where it will live. Measure the storage space, and the path to where it will run.
- Ask a dealer early for standby. Generac says a dealer is the best person to size a standby system, and a quote costs nothing.
Real-Life Scenarios: Which Generac Type?
These are typical situations that buyers describe in forums and reviews. They are examples to help you choose, not quotes from real people.
🏕️ The camper
You want lights, a coffee maker and phone charging at a quiet site, and you carry everything yourself.
You need the lightest, quietest generator in the range.
Best type: small inverter, such as the GP2500i or GP3300i
🏡 The careful homeowner
Outages are rare but can last days. You have a natural gas line and do not mind starting a generator.
You need big wattage, a 240-volt outlet and a fuel that does not run out.
Best type: tri fuel portable with a transfer switch
🧳 The frequent traveler
You are away for weeks at a time, and a failed sump pump or a thawed freezer would be costly.
You need power that comes back with nobody home.
Best type: air-cooled home standby from a Generac dealer
Generac Power Generators: FAQ
What types of generators does Generac make?
Open-frame portable generators, portable inverter generators, dual fuel and tri fuel portables, a diesel portable, portable power stations, and home standby generators. Its standby range runs from 10 kW air-cooled units up to 150 kW models.
What is the biggest Generac portable generator?
The GP18000EFI. Generac's website lists it at 18,000 running watts and 22,500 starting watts, with an 816 cc fuel-injected engine, a 14.2-gallon tank and a weight of about 443 pounds.
What is the smallest Generac generator?
The GP2500i inverter. It is listed at 2,200 running watts and 2,500 starting watts, and it weighs about 48 pounds.
Does Generac make a dual fuel generator?
Yes. The iQ3800 and iQ5200 inverters and the GP7500E run on gasoline or propane. The GP9500E Tri Fuel adds natural gas as a third fuel.
What size Generac standby generator do I need?
Generac says smaller homes may need a 10 to 18 kW unit, and larger homes with several air conditioners may need 22 to 28 kW. An authorized dealer can carry out a load assessment and give a free quote.
How loud is a Generac generator?
Generac says its home standby generators average 65 to 67 decibels, similar to a central air conditioner. The GP2500i inverter is listed at 53 dB(A) at 25% load. Open-frame portables are louder than inverters.
Your Generac Type Checklist
- Decide whether it must start by itself.
- Add up your running watts and largest starting surge.
- Check whether you need 240 volts.
- Choose your fuel: gasoline, propane, natural gas or diesel.
- Decide how much noise is acceptable.
- Compare running watts, not the number in the title.
- Check the 49-state or 50-state version.
- Check the weight and where it will be stored or installed.
- Plan the connection: cords, a transfer switch or a full standby installation.
- Read the manual and register the product.
The bottom line
Pick the type before the model. If you want backup power that looks after itself, talk to a dealer about a home standby unit. If you would rather start it yourself, the GP9500E Tri Fuel and a transfer switch cover most of a home.
As an Amazon Associate we earn from qualifying purchases.
Sources: Generac’s official website (generac.com): the portable generator and standby generator product lists, individual product pages and spec tables, and the home standby and portable FAQs; Generac dealer documentation for air-cooled standby ratings; Generac’s support site (support.generac.com); Amazon listings for the products named in this guide. All checked October 2026.
