Generator Maintenance and Information

How Much Fuel Does a Generator Need?

By November 4, 2019 November 19th, 2020 No Comments

Diesel Generator Fuel Consumption

We’ve previously written about the need to size a generator correctly to ensure proper operation and that you will have enough power to meet your needs. We’ve also looked at the different types of generators that are available and the types of fuel generators can use. When choosing a generator you’ll have to think about what kind of fuel you will want to use for it. Sometimes this decision is made for you, based on availability of fuel in your area or if you had a previous generator installed and want to use the same fuel tank and delivery system. In other cases, you get to make the decision from scratch and one of your first questions might be, “How much fuel does this generator require?” 


This is a particularly important question if you’re using backup generators, mobile generators, or portable generators since you’re less likely to have a topped off fuel tank standing by and ready to go. In the case of rental generators, you’ll have to plan ahead for fuel consumption so you can arrange delivery of fuel.

Fuel consumption is affected by a variety of factors not limited to the age and maintenance of the genset and the load level at which you operate the generator.

400 kW katolight diesel generator fuel tankHow To Plan Generator Fuel Needs

You can get a general estimate of fuel needs by consulting the owner’s manual or product guide, if available. Manufacturers usually rate generators at X hours per tank or gallon at a 50% load capacity. This should provide you with a baseline starting point. From there, you can figure out your specific needs keeping in mind that higher loads demand more fuel and lower loads use less fuel. 

Here is the critical information you’ll need to estimate fuel demands:


  • What is the generator size in kW?
  • At what load will the generator be run?
  • How many hours will the generator be running?

You can use our Diesel Fuel Consumption Chart or Natural Gas Consumption Chart to get an idea of how much fuel you will need to run your generator.

If you have any questions about estimating generator fuel consumption, feel free to contact Critical Power Products & Services for advice. Call 855-968-0176 or contact us online.