A portable generator is a hugely convenient thing to have. It can help you deal with power outages, take your camping trips to the next level, and so much more. But before you can buy a generator, you’ll need to calculate generator size, in other words, how much power it can output.

Thankfully, the process is simple. Let’s look at why calculating generator size requirements is important, and how to determine what generator size is needed. 

Why Do You Need to Calculate Generator Size Requirements

If you’re looking to purchase a generator, you might wonder why it’s important to calculate generator size requirements. 

In fact, calculating generator size needs, also referred to as sizing a generator, is the first and most important step in the buying process. This shows you how much power you need, to ensure you don’t have a generator that’s too small or too big.

If you go too small with your generator, you won’t have enough power for all your devices. You’ll be stuck deciding which devices get priority, and will lose out on a lot of the convenience of a generator.

If you don’t calculate your generator size needs and end up with one that’s too big, this can also be a problem. While you won’t struggle to power devices, you’ll end up paying quite a bit extra for power you’re not using.

So, to ensure your generator suits your needs, without going over budget, it’s essential to size your generator before doing anything else. Then, you’ll be ready to find the right generator for you. 

How to Determine Generator Size

https://www.youtube.com/watch?v=WxNFiLour3E&t=2s 

If you’re wondering how to determine what generator size is needed, the good news is that it’s easy. All that’s required to calculate generator size needed is some simple addition and hunting for some information.

Step 1 of how to determine generator size is to decide what electronics you’d like to power. Consider what situations you expect to use the generator, and what items you’ll need.

If you’re sizing a generator for home backup power, you’ll likely want to power things like fridges, cell phones, and lights. If you’re sizing a generator for camping, it might be things like portable induction cookers or even a portable projector. 

Once you’ve decided what you want to use, make a list of each item. Then, you’ll need to find the wattage requirements of each item and list that out too.

Keep in mind that some electronics have two wattage requirements, the running and starting wattage. Running wattages are the power consumed during normal operation, while the starting (AKA surge) wattage is the amount of power briefly needed to start the device.  Electronics with starting wattages are generally those with a motor, such as fridges, air conditioners, and microwaves. 

To find wattage information, there are a few different places to look:

• On the device itself, most commonly on the back or bottom of the device
• On the device’s power supply, such as the “power brick” for laptops
• In the user manual for the device

You’ll typically see wattage information in the same place you’ll see info such as the CE marking. 

Once you’ve listed out all the wattages, all that’s left to do is some simple addition to calculate generator requirements. Add up the running wattages, and then add the highest starting wattage to that. Now, you’ll know the size requirements for your generator.

Keep in mind that this is assuming you’ll only have one item starting or cycling at the same time. If you for some reason expect items to be starting or cycling simultaneously, add the starting wattages as those as well. However, this generally isn’t recommended. 

If you still can’t find wattage info, you can always estimate it using a calculator, such as our online portable generator sizing calculator. While it’s not as exact as checking the device itself, it still lets you get a solid idea of your power needs. 

Once you have this total, it’s recommended to add 15-20% of the total on top. This is to help add some flexibility for the exact load you’ll place on the generator. That way, you won’t risk overloading it or ending up not having all the power you need. 

How to Determine What Generator Size is Needed: Frequently Asked Questions

Still have some questions about how to determine what generator size is needed? We have the answers.

What Should I Do if I Can’t Find Wattage Information?

Wattage information is essential to calculate generator size needed, but sometimes it can be hard to find. Thankfully, you have a few options in this situation.

One option is to estimate based on information found online. While you may not find your exact model of device, you can easily find typical wattages of common electronics online.

Another option is to calculate wattage based on the volt and amp ratings of the device. Even if wattages aren’t listed, this info usually will be somewhere. If you multiply the voltage by the amperage, you’ll get the wattage of the device.

So for example, a 120V 10A device will consume 1200 watts of electricity.

Do All Electronics Have a Starting Wattage?

No, all electronics do not have a starting wattage. This is generally only for electronics with a motor, which briefly require more power to “spin up” the motor.

Common electronics with starting wattage requirements include:

• Fridges and freezers
• Microwaves
• Fans
• Air conditioners and heaters
• Tankless water heaters
• Pumps
• Dishwashers
• Electric kettles
• Washers and dryers
• Vacuum cleaners
• Blow dryers
• Blenders
• Power tools

So as you can see, many electronics do have a starting wattage requirement. But, it’s far from all of them. 

What Kind of Generator Should I Buy?

There are many kinds of generators available, and which one is right for you depends on many factors.

You’ll have to consider things like:

• What fuel type (or types in the case of dual fuel and tri fuel generators) to use
• Whether to use an inverter generator
• What kind of features you’d like in your generator
• And more

Thankfully, we have plenty of guides to help you choose the right generator for your needs!

Are Larger Generators More Expensive?

If you calculate generator requirements and discover your power needs are quite high, you might wonder if that also means a more expensive generator.

Generally speaking, yes, a more powerful generator will also be a more expensive generator. Because of this, it’s important to calculate your power needs. Otherwise, you may end up paying much more than you really need to. 

Now You Know How to Determine What Generator Size is Needed

The first step in buying a generator is knowing how to determine what generator size is needed. Once you have that information, you’ll be ready to shop for the perfect generator for your needs. Once that’s done, all that’s left is to put it to use and enjoy on-demand power, anywhere, any time. 

Sources:

1. https://kratopower.com/blogs/news/how-to-pick-the-best-home-generator-the-simple-guide
2. https://www.genpowerusa.com/blog/how-to-calculate-commercial-generator-size
3. https://en.wikipedia.org/wiki/CE_marking
4. https://www.packetpower.com/blog/electricity-basics-for-data-centers
5. https://generatorist.com/list-of-electric-appliances-their-wattage-usage
6. https://kratopower.com/collections/generators/products/duromax-xp13000hxt-13-000-watt-10-500-watt-500cc-tri-fuel-portable-generator-with-co-alert-in-blue
7. https://kratopower.com/collections/inverter-generators/products/4-500-watt-dual-fuel-portable-inverter-generator

Image sources:

1. https://unsplash.com/photos/OGKaLGt1VYY
2. https://unsplash.com/photos/dvTSuIAHbiA
3. https://unsplash.com/photos/8gXzLPWPu7E