What Will 12000 Watt Generator Run? (With Calculation)

A 12000-watt generator is a giant alternative electricity source in a 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 a 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. 

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. 

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 drills, air compressors, and battery chargers are widespread appliances for construction sites. So, it would help if you calculated it this way. 

ApplianceRunning WattStarting WattTotal NumberTotal Watt
Portable Air Compressor1200-watt1500-watt11500
Hand Drill (.inch)600-watt0-watt21200
Battery Charger (15-amp)500-watt700-watt21400
Circular Saw1400-watt2300-watt24600

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 conditioners, refrigerators, freezers, washing machines, electric cookers, coffee pots, sump pumps, or Well-pump, lights are the most important to run during a 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 W2100 W12100 W
Dehumidifier240 W0 W1240 W
LED Light Bulb (Common)25 W0 W125 W
Sump Pump (1/2 HP)1,050 W2,150 W12,150 W
Coffee Maker1,000 W0 W11,000 W
Deep Freezer500 W1,500 W11,500 W
Refrigerator / Freezer700 W2,200 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.

Choosing the right 12,000-watt generator

When selecting a 12,000-watt generator, consider the following factors to ensure you make the best choice for your specific needs:

Fuel options

Generators can be powered by gasoline, propane, or diesel fuel. Each type offers different benefits in terms of fuel efficiency, cost, and emissions. Gasoline generators are often less expensive upfront but tend to have higher operating costs. Propane generators emit fewer pollutants and have a longer shelf life for fuel, while diesel generators are known for their durability and fuel efficiency. Assess your fuel availability and preferences to make an informed decision.

Noise level:

Generators can be noisy, which can be a concern for residential use or public events. Look for generators with noise-reducing features, such as enclosures or mufflers. Also, consider the generator’s decibel (dB) rating; lower dB ratings indicate quieter operation.


A 12,000-watt generator can be quite heavy, so it’s important to consider ease of transport. Wheeled frames and handles make it easier to move the generator around your property or between locations. Some generators even come with folding handles and wheel kits for added convenience.

Safety features and certifications:

Look for generators with built-in safety features such as low-oil shutdown, overload protection, and automatic voltage regulation. This help protects both the generator and the appliances connected to it. In addition, check if the generator has been tested and certified by recognized organizations, such as Underwriters Laboratories (UL) or the Canadian Standards Association (CSA).

Related: Does Generator Charge Its Own Battery?

Price and warranty:

The cost of a generator can vary greatly depending on the brand, features, and fuel type. Set a budget for your generator purchase and research the options within your price range. A good warranty is also essential, as it provides peace of mind and ensures that you’re protected if any issues arise with your generator.

By considering these factors and understanding your power needs, you’ll be better equipped to choose the right 12,000-watt generator for your home, business, or recreational activities. Remember to always prioritize safety and follow the manufacturer’s guidelines for proper use and maintenance.

A 12000 Watt Generator for construction site

How to Maintain a 12,000-watt generator?

Proper maintenance is crucial for ensuring the longevity and optimal performance of your 12,000-watt generator. By following a regular maintenance schedule and addressing any issues promptly, you can keep your generator running efficiently and safely. Here are some key maintenance tips for your 12,000-watt generator:

Regular maintenance and servicing:

  1. Consult the owner’s manual: Always refer to the owner’s manual for the specific maintenance schedule and guidelines provided by the manufacturer. This will give you a clear understanding of the recommended maintenance tasks and their frequency.
  2. Change the oil: Regular oil changes are critical to keeping the engine running smoothly. Typically, you should change the oil after the first 20-30 hours of use, and then every 50-100 hours of operation, depending on the manufacturer’s recommendations.
  3. Check and replace air filters: A clean air filter ensures that the engine receives an adequate supply of clean air. Inspect the air filter regularly and replace it as needed, or at least once a year.
  4. Inspect and replace spark plugs: Worn or fouled spark plugs can reduce engine efficiency and make starting the generator difficult. Check the spark plugs periodically and replace them as necessary.
  5. Clean the fuel system: Over time, sediment and deposits can accumulate in the fuel system, potentially causing blockages or other issues. Use a fuel stabilizer to keep the fuel fresh, and periodically clean the fuel tank, fuel lines, and carburetor.

Proper fuel storage and safety:

  1. Store fuel in approved containers: Use containers specifically designed for fuel storage, and follow local regulations regarding fuel storage and quantities.
  2. Keep fuel fresh: Gasoline can degrade over time, leading to performance issues. Use a fuel stabilizer to prolong the life of stored fuel, and rotate your fuel supply regularly to ensure freshness.
  3. Store fuel safely: Keep fuel containers away from living areas, heat sources, and direct sunlight. Store them in a well-ventilated area to minimize the risk of fume accumulation or accidental ignition.

Troubleshooting common generator issues:

  1. Generator won’t start: Check the fuel level, oil level, and spark plug condition. Ensure that the choke is set correctly and the battery (if applicable) is charged.
  2. Generator runs but provides no power: Inspect the circuit breakers and fuses, and make sure the generator is properly grounded. Check for any loose or damaged wiring.
  3. Generator output is unstable: This can be caused by an overloaded generator, a dirty carburetor, or a malfunctioning automatic voltage regulator. Address the specific issue based on the symptoms and consult the owner’s manual for guidance.

By following these maintenance tips and addressing any issues promptly, you can maximize the life and performance of your 12,000-watt generator, ensuring that it is ready to provide reliable power when you need it most.


Can a 12000-watt generator run a house?

Yes, A 12,000-watt generator has the capacity to power a house. But the extent to which it can do so depends on the specific power requirements of the house. A generator’s wattage indicates the maximum amount of power it can produce. Also, it is crucial to consider the total power needs of the house before determining if a 12,000-watt generator is sufficient.

To assess whether the generator can run a house, you must consider the power requirements of various appliances and systems in your home. Commonly used appliances like refrigerators, air conditioners, heating systems, lights, and electronics all contribute to the overall power demand.

For example, a 12,000-watt generator can easily handle essential household appliances like refrigerators, lights, and electronics. However, if you have a central air conditioning unit or an electric water heater, these appliances alone can consume a significant amount of power, possibly exceeding the generator’s capacity.

Will a 12000 watt generator run AC?

Yes. A 12,000-watt generator should be able to run a typical central air conditioning unit. Please make sure that the unit’s power requirements do not exceed the generator’s capacity. However, it is important to consider the starting wattage or surge wattage of the AC unit.

Air conditioners often have a higher power draw when they start up, requiring additional power to overcome the initial load. This surge wattage can be significantly higher than the unit’s normal running wattage. If the surge wattage of the AC unit exceeds the generator’s capacity, it may cause the generator to overload and shut down.

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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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