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Generator Size Guide: What Size Do You Need?

Having a generator for your building or job can be incredibly useful, but figuring out the right generator size can be tricky. How much power do you need, and what equipment or appliances will you need to run if the power goes out? Or even if you want to power things full time?

Here is a quick guide for figuring out your ideal generator size so that you can help your business plan accordingly.


Different Kinds of Wattage

There are two main types of wattage you'll need to factor into your decisions for a generator. These are starting (or surge) watts and running (or continuous) watts. 


A lot of equipment will require a higher amount of startup power to get up and going. This is the surge wattage you'll have to factor in with your generator and can generally be calculated for a machine as 3x the running wattage.


Running wattage is, as the name implies, the amount of power a machine will need to operate. Once a machine is past the initial warmup, the running wattage is what your generator will need to keep up with. You'll need to look at the type of generators available to see whether they can handle your running and your starting wattage for the equipment in your building.


Doing the Math for Generator Size

There are several calculations you'll want to make to ensure you have the right-sized generator for your business. While the calculations can be a little tricky, it's important to make sure you have something big enough to handle your energy needs!


The first method is to look at your starting and running wattage to see what size generator can handle the number of kilowatts your machines will require. Generally, you'll want to add your running wattage to your surge wattage for a total of what your generator wattage needs to be. Unfortunately, it can be difficult to find your specific generator power needs for every single machine and aspect of your building.


Another method to determine your generator sizing is to look at your square footage. The basic generator size calculator equation for this method is 50kW + 10 W/square foot for retail stores. For other places, the equation is 50kW + 5 W/square foot.


Note that this method is a general rule of thumb and will vary a good bit depending on your specific needs. Probably the most accurate way to determine your necessary generator size is to look at your historical power usage.


Make sure to examine at least a year's worth of utility bills! Your power usage may change seasonally, and you want to get an idea of your highest power needs. Take the month with the highest KWH and add a buffer to it to give yourself leeway in case you have another month of high power needs.


Let The Experts Help You

Picking the right generator size for your business can be tough, but that's what we're here for! If you have any questions or concerns, we'd love to help. Feel free to get in touch with us at Southern Rewind, and we'll do our best to help you take care of all your energy needs.