Gensets Selection Points

What Size Diesel Generator Do You Need?

Perfect House Limited Blog

The only critical aspect before choosing a generator for your application is determining the right size for your establishment. It could either be that you need a generator to power some of your applications or your entire facility. To do either of that, you need a generator with a capacity to at least equal the peak consumption of all your applications running at full swing.

That sounds like one could go purchase the highest rated diesel generator so that it can take whatever is put at it.

NO! Unfortunately, that is something we can’t do.

It will not only damage some of the applications connected to the generator but also be incredibly expensive to purchase. Hence, determining exactly the size of the generator you need is the most crucial step before buying a diesel generator set. Here are a few steps that you need to follow in order to determine the right size.

Determine your power requirement

Start with making a clear list of what all you need powered during a power outage. It could either be a few devices or your entire house. The list must contain every single item from the bulbs, fans, and everything else you will connect to the generator. Then, calculate the starting and running wattage of all your appliances. These details will be clearly listed either on the appliances itself or their user manuals. You can also call up the customer service center of your appliance provider to note down the exact values.

Then, get back to your physics classroom by converting all the values into either kW (kilowatt) or kVA (kilo-volt-amperes). You need to do this since your diesel generator set will be rated according to kW or kVA.

If you cannot find wattage mentioned on your appliance, then calculate Wattage = Amperes X Volts. Sometimes, you need to include load factors since electrical appliances are not 100% efficient.

When you add up all the wattages, you get the maximum required wattage of your equipment. This will be in kW. If your generator set is rated in kVA, then you need to divide the generator power factor with kW.


kW/Power Factor = kVA

Power factor of diesel generator sets is usually 0.8 since electrical systems do not run in an ideal situation where kW=kVA.

Hence, for example, if your total wattage is 1000 kW, then 1000 kW/0.8 = 1250 kVA.

This means that the minimum power that your diesel generator needs to provide is 1250 kVA.

Contact your generator company

Now that you have determined what size you need to purchase; you need to discuss this with your generator provider. You need to enquire about the pricing and the physical space the generator will occupy. If possible, share your calculations with the generator company and re-affirm your requirements. Then, determine the running and maintenance cost of the generator you have in mind.

Sometimes, there are several innovative generators that are tailored to suit your equipment. Such generators are customized to the purpose and require potentially less maintenance than an average generator.

You can also have an electrician visit your site and determine the most ideal location for placing the generator.

Before you buy a diesel generator set, it is crucial to consider the perfect size that you require for your application. This will ensure the increased usability of the generator, provide consistent performance, decrease any risk of fire or malfunction. You can also save up huge bucks on the purchase, fuel, and maintenance costs of your diesel generator sets.

To get the perfect requirement for your applications, get in touch with us at You can also call us on 022-22677357 / 022-62611900.