What Will A 12000 Watt Generator Run?- [Actual Potential]

If you are unaware of the potential of your 12000-wattage generator, this guide is all about unleashing the actual power of a 12kw gen set.

A 12,000-watt generator could run almost every appliance or power equipment of a household, RV, or job site including the ACs, Refrigerator/freezers, microwaves,  Washing machines, electric dryers, heating systems, welders, Electric Drills, Saws, etc.

what will a 12000 watt generator run?

Understanding The Generator Wattages

Rated/Running Watts: Number of wattages a machine can supply continuously to run the appliances/equipment in a stable condition.  

Starting/Surge Watts: Number of wattages a machine can produce for a short time to provide initial push or inertia to the motorized appliances.

Surge wattages can’t be ignored at any cost as they have the responsibility to run heavy-duty appliances like air conditioners, sump pumps, heat pumps, etc.

You can skim the user manual or specification section of the generator to know the exact Starting watts/amps of the generator.

What Will a 12000 Watt Generator Run?

Below is the table of the appliances that can be easily run by the 12kw generator

ApplianceRunning WattageStarting Watts
Electric Water Heater 4 kW40000
Microwave Oven 600 W6000
Deep Freezer5001500
Furnace Fan 1/3 HP7001400
Electric Drill 1/2 inch 5.4 Amps600900
Box Fan 20″200350
Planer/Jointer 6-inch600900
Food Processor4000
Iron (Clothes)15000
Toaster Oven12000
Iron (Waffles)12000
Airless Sprayer6001200
Sump Pump 1/2 HP10502100
Humidifier 13 gal.1750
Electric Grill 1.6 kW16000
Central AC 40.000 BTU60007300
Coffee Maker10000
Light LED Bulb 10 W100
Ceiling Fan100300
RV Air Conditioner 7.000 BTU9001600
Curling Iron15000
Vacuum Cleaner 12 Amps14402400
Electric Stove 2kW20000
RV Air Conditioner 10.000 BTU12002000
Halogen Work Light 300 W3000
Sump Pump 1/3 HP8001300
Window AC 12.000 BTU15002300
Security System5000
Belt Sander12002400
Planer/Jointer 6 inch18002500
Air Compressor 1 HP16004500
RV Air Conditioner 13.500 BTU16002500
Window AC 15.000 BTU19002900
Table Saw 10 inch20002600
Garage Door Opener 1/2 HP9002600
Well Pump 1/2 HP10002000
Curling Iron15000

How Many Appliances Can I Run Simultaneously?

It depends, 10  to 12 normal-wattage appliances will not be a problem for a 12000-watt machine, however, if you are going to operate some of the super power-hungry appliances like Air conditioners, dryers, sump pumps, etc. you may have to go for the bigger units.

We recommend doing the wattage calculation to know the actual capacity.

How to calculate wattage Needs Precisely:

  • Write down the running and starting wattages of the appliances you are going to run, make sure to keep them in a tabular form. Also, write the starting and running watts in a separate column.
  • If you have found the wattage ratings in amps and you are not comfortable with the calculation make sure to convert them with the help of ohms law. Below is a practical example to do that.

Ohm’s Law = W = Volts X Amps

For example, An air conditioner consumes 18 starting and 12 running amps at a voltage of 220.

 Running Watts = 220 X 12 = 2640 watts

Starting Watts = 220 X 18 = 3960 watts

  • Sum up the starting and running wattages of the appliances and compare them with the power ratings of the machine you are going to own.

NOTE: We recommend keeping a margin of at least 10% of the load so that the generator can run smoothly without the fear of overloading. Pulling 100% load from the gen set wouldn’t only decrease the longevity but also reduce the runtime as well.

How Many Amps Will a 12000-Watt Generator Run?

I got the following reading from my Duromax xp12000eh.


Are 12000 Watt Generators Any Good?

A 12kw machine is more than enough for not only the household essentials but also the work site’s power-hungry appliances like different saws, belt sander, drills, etc.

As per my experience, a solid 12000-watt gen set is a one-stop solution to cope with extended blackouts.

Can I Power My House With a 12000 Watt Generator?

It depends; typically a 12000-watt generator is more than enough for a small to medium house with a bunch of necessary appliances like air conditioners, refrigerators, microwaves, heating systems, etc., however, if you want to operate multiple power-hungry appliances like central air conditioner, dryers, worksite tools, etc. simultaneously, you should have to think about the bigger machines of 15 – 20kw.

How Long Will a 12,000-Watt Generator Run?

The runtime of the generator is solely dependent on the efficiency, tank size, and how much load you are pulling.

Generally, a brandable machine with decent efficiency should provide at least 7 – 8 hours of runtime at 30 – 40% load.

Note: With increased load, you will see a significant drop in the runtime.

How Much Does a 12,000-Watt Generator Cost?

It depends on the brand, features, and the built quality of the generator you want to own, As per our survey a solid branded 12kw generator will cost you around $1000 to $3000.

What Size Breaker Do You Need for a 12000-Watt Generator?

Since 12000-watt generators are well known for their 240V supply we recommend purchasing at least a 50 amp breaker for smooth power supply. 

As per the Ohms:

W = V x Amp

Amp = W/V

Amp = 12000/240

= 50 amp

Will a 12,000-watt Generator Run a 5-ton AC Unit?

It depends on the size, efficiency, and power ratings of the generator you own, below is the list of the most common air conditioners that can be easily run by a 12kw gen set.

AC UnitRunning Watts Starting Watts
Split air conditioner3,0004,500
RV air conditoner2,5004,000
Central Air conditioner5,0008,000
Window air conditioner3,5005,000


Though a 12kw generator will be ideal for a small to medium household, RVs, worksite, etc., still, a basic wattage calculation should be done to not only save your initial investment but also the ongoing cost of fuel, maintenance, etc.

Don’t go for a 12kw machine when your need is hardly 5kw, bigger machines will need more fuel and maintenance costs.

FAQs – Frequently Asked Questions

Will a 12000 Watt Generator Run an RV AC?

Typically the wattage of the RV Air conditioners lies between 500 (5,000 BTU) to 2700 watts (27,000 BTU) which isn’t a big deal for a 12000-watt machine.

Will a 12000 Watt Generator Run a Window AC?

Modern Widow air conditioner consumes 450 – 1300 watts depending on the size and cooling capacity, a 12kw could run even 3 – 4 of them.

Will a 12,000-watt Generator Run a 4-ton AC Unit?

Well, it depends on the model, type, power ratings, and seasonal energy efficiency ratio (SEER) of the AC unit you own.
Generally, a 12kw machine is more than enough to run a window, RV, or split air conditioner, however for a central AC unit, you may have to consider a bigger one.

Will a 12000 Watt Generator Run a Welder?

Yes, a normal welder of 4000 – 7000 wattage will not be a problem for a 12kw machine.

Will a 12,000-watt Generator Run Central AC?

Yes, a modern central air conditioner of 12,000 – 42,000 BTUs isn’t a problem for a 12kw machine, however, if you own an inefficient heavy-duty old-school central air conditioner you may have to consider a bigger machine.

Alex black

Alex Black

Alex Black is a seasoned electrical engineer with a remarkable 8-year track record specializing in appliances, generators, and transfer switches. With extensive hands-on experience in the field, Alex possesses a deep understanding of electrical systems and their intricate workings. Throughout their career, Alex has consistently demonstrated expertise in designing, troubleshooting, and maintaining various electrical appliances.

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