What Will 12000 watt Generator Run? (With Calculation)

A 12000-watt generator is a giant alternative electricity source in the prolonged power outage. Luckily, the manufacturers offer the portable version of the 12000-watt generator for home and commercial use. So, it does not matter whether you live in an off-grid farmhouse or a power outage-prone area; this is a complete package for your home.

A 12000-watt portable generator can run all the appliances of your home at a time or partially. It can provide a continuous electricity supply for your whole house. A 12000-watt generator is also a good option for construction work.

Though a 12000-watt generator is heavy, you could quickly move the generator from one place to another place easily. Because this portable generator comes with wheels like the 3000-watt portable generator.

I will elaborate on what a 12000-watt generator can run and some real-life case studies in this article. So, let’s get started. 

What Will A 12000 Watt Generator Run

Surge Watts vs. Rated Watts 

Usually, the generator has surge watts and rated watts. Surge watts mean the peak wattage of the generator. You will get the surge wattage only for the first 5 seconds while starting the generator. 

On the other hand, rated watts mean the continuous wattage supply of the generator. 

In the case of a 12000-watt generator, you will get 9000-watts to 9500-watts rated watt. And definitely, you will get 12000 surge watts. 

That means using a 12000-watt portable generator, you will get approximately 9500-watt energy. This is the typical scenario, indeed. 

How Long Can You Run a 12000-Watt Generator?

Actually, the run time varies from brand to brand. Also the types of generators matter. Additionally, it depends on the fuel tank size. Since I am talking about the 12KW portable generator, you cannot connect with the natural gas line like a standby generator. 

Usually, you will get 7-gallon to an 8.5-gallon tank range for a 12000-watt generator. The more the tank size will be, the extended the generator will run. This is a straightforward calculation here. But you will get some exceptions here also. 

Like the A-iPower SUA12000E 12,000-Watt Gasoline Generator, come with a 7-gallon tank. But you can run this for 9.5 hours at 50% load. That means it is a fuel-efficient generator. 

So, if you have a fuel-efficient large tank generator, you can run your generator for 8 hours to 13 hours continuously. 

A general Comparison for the 12-KW Generator

Best Light Weight
A-iPower SUA12000E
A-iPower SUA12000E
  • Weight: 206 pounds 
  • 12000 starting watts and 9000 running watts
  • 7-gallon fuel tank
  • 9-hours run-time at 50% load


Check Price On Amazon
Best Dual Fuel
DuroMax XP12000EH Dual Fuel Electric Start
DuroMax XP12000EH Dual Fuel Electric Start
  • Weight: 224 pounds
  • 12000 starting watts and 9500 running watts
  • 8.3-gallon fuel tank 
  • Propnae and Gasoline powered 
Check Price On Amazon
Pulsar G12KBN Dual Fuel Generator Pulsar G12KBN Dual Fuel Generator
  • Weight: 209 pounds
  • 9500 Rated Watts and 12000 Peak Watts
  • 8-gallon fuel tank
  • 12-hours runtime 
Check Price On Amazon
Westinghouse WGen9500DF Dual Fuel Westinghouse WGen9500DF Dual Fuel
  • Weight: 220 pounds
  • 12500 peak and 9500 running watt 
  • 12 hours runtime 
  • 6.6 gallon fuel tank 
  • Electric, Remote, Recoil start
Check Price On Amazon

What Will A 12000 Watt Generator Run?

Well, now comes to the point. Whether you are using a 12000-watt generator for a construction site or home, you can run 4-5 appliances at a time. Yes, you could run more than that. But it depends on the starting watt and running watt of your devices. 

Let’s talk about some real-life use. 

A 12000 Watt Generator for construction site

For construction site 

Say, you want to use a 12000-watt generator in a construction site where a power outage is typical. Even it could be an off-grid area. In these cases, a 12KW portable generator could be a great solution indeed. 

You already know you will get 9000 watts -9500 watt net energy from a 12000-watt generator. Additionally, to avoid damaging your generator, you should not run your generator for more than 75% of its capacity. It is crucial, indeed. 

Circular-saw, hand drill, air compressor, and battery charger are widespread appliances for the construction site. So, it would help if you calculated it like this way. 

ApplianceRunning Watt Starting WattTotal NumberTotal Watt
Portable Air Compressor 1200-watt1500-watt 11500
Hand Drill (.inch)600-watt 0-watt21200
Battery Charger (15-amp)500-watt700-watt21400
Circular Saw 1400-watt2300-watt24600
Total =8700

That means you need 8700 watts to run those appliances on time. On the other hand, your generator produces 9000 watts. So, you could run all the appliances at a time smoothly. Also, you can add light to this list. They need a maximum of 20 watts. Or, if you want to use a more powerful searchlight for your job site, calculate this way. 

For Home use 

For a medium-sized home, a 12000-watt portable generator is more than enough. Apart from meeting the demand for your home appliances, you could run some garage tools with this giant portable generator. 

Air conditioner, refrigerator, freezer, washing machine, electric cooker, coffee pot, sump pump, or a Well-pump, lights are the most important to run during the power outage. 

Let’s have a calculation with the estimated power of these appliances. 

ApplianceRunning WattStarting WattTotal NumberTotal Watt
Central AC (6,000 BTU) 700 W 2100 W12100 W
Dehumidifier 240 W0 W1240 W
LED Light Bulb (Common) 25 W 0 W125 W
Sump Pump (1/2 HP) 1,050 W 2,150 W12,150 W
Coffee Maker1,000 W0 W11,000 W
Deep Freezer 500 W 1,500 W11,500 W
Refrigerator / Freezer700 W 2,200 W12,200 W
Television (49″ LED)85 W0 W185 W
Total =9300 W

Please remember, these are the estimated wattage only. It could be varied from brand to brand and product to product. Please, see the manual of the product to get the exact information. I hope you have understood the process.

you just need to ensure that you are not crossing the maximum power output of your generator. That is all.


A portable generator is one of the mandatory tools for preparing for the hurricane or ice storm season. This one is a life-saving item indeed. On the other hand, for commercial purposes, you must have an alternative power system. So, a generator is an excellent way to keep all things regular. 

If you have the ability, you could invest in a 12000-watt generator. It is worth the money indeed. You need not think about the power outage if you have this giant generator. 


Rayan is an engineer, lives in a farmhouse. He has a passion for electronics and alternative energy. He loves to share his thoughts with other people. That is why he started the blog.

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