How To Choose the Correct Size Diesel Power Generator for Your Needs

Power outages cost American businesses about $150 billion annually. If you’ve experienced a power outage, you know how frustrating it is to sit dead in the water while you wait for the power to come back on. Having a diesel power generator can get your business up and running when the power fails. However, you can’t just buy any generator. You need to find the best diesel generator for your needs.

This guide will help you size your generator to your power needs.

Home or Commercial Use?

Your first step is to decide if you need a residential or commercial generator. Diesel generators for home use are typically a smaller portable diesel generator. These are designed to run one or two pieces of equipment at a time.

Commercial diesel generators are large and designed to run an entire facility. They will permanently hook into your electrical system and act like a diesel standby generator that automatically starts running when the power goes out.

Power Needs

To compare diesel generator sizes, you need to know how much power you’ll need to produce. To figure this out, you’ll make a list of all of the items that need to be powered by your generator.

Once you make your list, mark the starting and running wattage for each item. You need both of these numbers because the starting power pull is higher than the running. Your generator needs to be able to supply enough power during the peak spikes.

The final step is to calculate your total power consumption in either KVA or KW. Be careful with this; sometimes, equipment lists power needs in amperes. You’ll need to convert the amps to watts for an accurate calculation.

Type of Load

Not all power consumption is the same. Your generator needs to be able to supply power for the type of load you’re running.

  • Uninterrupted power supply
  • High engine loads
  • Illumination loads
  • Variable frequency devices
  • Frequency variation loads
Ask the Experts

The smartest thing you can do is have a certified electrician perform an inspection and calculate your power needs for you. They’ll be able to give you an accurate determination while also helping you estimate your future growth needs.


Do not blindly buy the most expensive generator you can find. You’ll waste your budget and likely buy a generator that is much larger than your power needs. Instead, buy the best quality generator for your budget that’s also appropriately sized for your power needs.

Do not try to save money by buying a lower quality or undersized generator. While you may save in the short term, your long term consequential expenses will far outnumber your savings.

Purchase Your Diesel Power Generator

With these tips in mind, you’re ready to start sizing your diesel power generator. Start by knowing what the application is and what you want to power. Then you can calculate your power needs and consider the other factors to find the perfect generator.

Check out our other home articles for advice on decor, improvements, and home maintenance.