Is a 4000 Watts Generator Enough For Me – Stop Wondering And Start Reading!

You are conflicted about buying a 4kW generator, aren’t you?

Will it be enough for my house? Am I overcompensating? Is it the perfect fit for my home? 

These are queries you are bound to have when making this expensive purchase. While research seems daunting, it is not avoidable and needs to be addressed with proper attention.

 So, let us put you out of this misery!

Learn The Basics – To Avoid Mistakes Which Others Are Making

It is not an exaggeration to say that a 4000 watts generator is immaculate for a customer wanting high portability and high electrical capacity. 

It is a flawless blend of mobility and power. 

Cost – Frankly, Not So Much

The generator costs usually vary from $800 to $2000. Several brands have a model dedicated to this power, for example, Generac, Honda, Duramax, etc.

This cost is dependent on additional features, brand, warranty, etc. The fancier your generator, the higher you pay. 

Fuel – Endless Choices

It comes with different fuel models, and you can buy a single, dual or triple fuel generator. Furthermore, you can convert a single fuel into the latter variation using conversion kits. 

Generators run on three kinds of fuel: natural gas, gasoline, and diesel. You can make this decision based on your location, budget, etc. 

The latest versions of a 4000-watt generator are solar-powered, and they rely on a battery and are usually compact size. However, such models in this capacity have yet to be explored extensively. 

The Running Time – A Controversial Topic

It is difficult to put a number on the run time of any generator as each model varies from the next greatly. It depends on the fuel consumption and the load you put on the power source. 

However, putting a simple value would be approximately 10 hours at 50% load. The highest at half of its capacity would be around 12 hours

This means if you utilize the generator for appliances of watts lower than 2000-watts, it would easily function for more than ten hours straight. As most consumers buy this generator for outdoor or travel activities, it is safe to say that it will run for a very long time

The Wattage Story

Now that you know what you are getting yourself into, it is time to talk numbers. To determine whether this amount of energy is adequate for you, first, you need to understand what 4000 wattage means and how it can help you?

What Is Wattage? 

Wattage is the measure of the energy a device needs to function. This electrical output varies for each appliance and can usually be found on the information label for most devices. You can also refer to the retailer’s website or the manual. 

A simple way to remember wattage is that the heavier the device, the more wattage it requires. 

If your appliance does not have wattage, it is bound to have other units called Amperes (A)  and Voltage (V). Therefore, you need to calculate the wattage using a simple formula. 

The mathematical equation that determines wattage is:

Wattage = Amperes x Volts 

Your device will work on either 120 V or 240V. The current supply or ampere may vary for all. 

The Two Types

When you say you have a generator of 4000 watts, you need to make sure if it is the starting or running wattage that you are talking about.

Running Wattage

This is the amount of power any device requires to function continuously, and it stays constant throughout the usage and is needed for an extended time. If a device has two wattage values without labels, the smaller value is always the running wattage. 

It is also known as rated power or continuous wattage and can be different for the same device depending on the fuel type.

Starting Wattage

Surge wattage or peak wattage is the energy needed by any appliance with a motor. It is a sort of booster energy necessary to kick start the machine. It is the highest value any device can sustain and lasts for a few seconds only. 

Onto Your Generator

If your generator of 4000 watts usually refers to the starting wattage, the running power will be a few hundred fewer. Typically, the value will go up to 3.6kW. If the rated capacity is 4000 watts, your surge power will quickly be at least 4.3kW.

It is better to purchase a generator with a continuous wattage of 4kW because it creates fewer misunderstandings and is easier to remember.

It is essential that you match both these wattages with high accuracy as an error in either can cause you problems. 

If your generator’s surge wattage is low, your devices will not be able to start and fail without function. However, if the running wattage does not meet, your appliances will obviously not work. 

Extra of either is a waste of money and energy. 

The Dangers Of Inaccuracy 

Overestimating the generator is a common mistake several users make, and this can cost you a lot of time and money. However, those are not your biggest concerns. 

If you push the boundaries of the power source’s capacity, you might have the risk of electrocution, or worse, an explosion

If you wish to run the whole house on your generator, you should prefer a standby or whole house generator for your needs. A portable one will not carry all the weight and cause inconveniences to you. 

To find out more about whole house generators, you should refer to our detailed manual here

Go Easy On Your Generator

If your generator is used for a prolonged time and is powering essential equipment, it is best you cut the energy supply some slack. Many users tend to overdo their connections to the generator and forget that it is a sensitive electronic device

They then use the machine at its full load and take as much power from it as they can. This is extremely dangerous!

Running the generator at its maximum load can strain the machine and cause an internal breakdown, and it cannot support the weight and shuts down instead. 

This is why experts suggest that you should always use your generator at a maximum of 90% of its power. This means that a generator with 4kW running power can efficiently support 3600 watts of the appliance. 

When handled with care and attention, your generator’s lifespan increases by several months and, in some fortunate cases, even years. 

What Appliances Need, Appliances Get

You are now well-versed with the wattage of your generator. However, it does not end there. You need to know how many electronics you will be using during a power outage and the total power required. 

We have put up a table of all the essential household appliances and the related wattages beside them to aid you. 

Chart of Household Appliances and Their Wattages:

AppliancesStarting Wattage (watts)Running Wattage (watts)
Ceiling Fan7060
Cell Phone ChargerN/A25
Clothes Dryer67505400
Electric Heater (Fan)2 0001 000
Electric Thermal RadiatorN/A500
Electric Water HeaterN/A4 000
Electric Water Heater (tankless)6 6002 200
Full-Size Refrigerator2200700
Flat Screen TV120120
Furnace Fan Blower (1/2 HP)2 350800
Furnace Fan Blower (1/3 HP)1 400700
Garage Door Opener2 350875
Heat Pump4 7004 500
LCD Monitor3030
Light Bulb (conventional type)N/A75
Light Bulb (LED)N/A9
Space HeaterN/A1 800
Sump Pump (1/2 HP)2 1501 050
Sump Pump (1/3 HP)1 300800
Window Air Conditioner (10 000 BTU)36001200
Washing Machine22501150
Well Pump (1/2 HP)2 1001 000
Window AC (12 000 BTU)9 7503 250
*These values are merely an estimate; your appliance’s power consumption may differ

Here’s How You Calculate:

You can now calculate the total running wattage and starting wattage your generator needs to provide. The math is quite elementary for this. 

These are the steps you need to take: 

1. First, make a list of all the devices you will be using in a crisis or emergency. Furthermore, if you plan to use the generator for recreational activities, modify the list accordingly. 

2. Note down each electronic device’s starting and running wattage separately as neither can be missed. 

3. Add all the running wattages together to find the total required wattage of your house. 

4. Next, add at least 300 watts into that value to allow a buffer for your generator. 

Remember, we spoke about letting your generator breathe? 

5. To determine starting wattages, you must first find the highest starting wattage of all your chosen devices. Next, add this value to the total rated power to find the generator’s surge power.

You will now have a complete list of all the power required by your generator. This value may or may not be above 4000 watts, and if it is not, then you are in luck!

However, in the given scenario that you crossed the limit, you need to assess different emergencies and sort your priorities accordingly. 

Not to worry! We are here to help you!

Exemplary Example

You can face various scenarios in your daily life for which you need to be prepared. To give you an idea about how many devices your generator can sustain at once, we prepared an example for you: 

The One With Constant Blackouts

If you happen to live in an area with terrible weather conditions or an electrically unstable one, you often face power outages. This means you need to adjust your lifestyle accordingly and have your surroundings functional. 

The initial electronics to put on the list are a few light bulbs to ensure the darkness does not engulf you. Each light requires 75 watts rated power, estimating it to:

75 x 5 = 375 running watts and zero surge power.

You still have plenty to go! 

Another essential you should be looking out for is a cell phone charger, as active communication during an emergency could save your life. This would be an addition of merely 25 watts

The calculation for three cell phone chargers would look something like this : 

375 watts + 3(25 watts) = 450 watts of continuous power 

And you haven’t even touched the surge watts. Way To Go!

With approximately 3500 watts left, you should now turn to bigger appliances. A refrigerator is one of the most powerful machines in a household. You will die of starvation in a crisis without fresh food, so let’s add it to the list!

A fridge occupies about half of the surge power of a 4kW generator with an overwhelming value of 2200 watts. However, its running wattage is a stable 700 watts. 

So the value accumulates to: 

450 + 700 = 1150 running wattage

The good news is your generator can sustain all of that without any difficulty! These are the primary devices in any household and should be considered at all costs. 

Your Preference…?

It is best if the last device you choose is of our preference. It can be a life support system, a piece of office equipment, or simply an entertainment device. 

This is just an example of a group of electronics that can work together. You can mix and match according to your house or business needs. The calculation will be pretty similar, so you do not have to worry if your set looks the opposite of ours. 

Remember, your goal is to separate two hundred watts as a buffer for each type of wattage, and you should be able to adjust that without ease.


After reading the article, you should have a good idea about the 4000 watts generator and how many devices it can support simultaneously. The calculations are simple. 

However, if you still wish to avoid math, you can hire an expert to calculate for you.

In short, a 4kW generator can run several smaller appliances with only one or two heavy electronics. Therefore, it is best not to test your generator abilities by simultaneously plugging in more than two high-duty machines.

A 4000 watts portable generator is enough for your needs, and we just proved it to you!

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