GFE Power Products kVA Calculator

Choosing the right generator size can be challenging, especially if you're not familiar in the various power units used for diesel generators. The calculators on this page are designed to help you determine the appropriate generator size.

For further assistance or to move forward with your inquiry, please don't hesitate to contact us.

Disclaimer: These figures are approximate and intended as a general guide only. For advice tailored to your project, please contact our team

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Understanding Generator Sizing and kVA Ratings

Selecting the correct generator size is crucial. If it’s too small, you risk power failures and equipment damage. Too large, and you're wasting fuel and money. That’s where kVA, kilovolt-amps, comes in. It’s the industry standard for measuring a generator’s power capacity, including both real and reactive power. What is kVA? Learn more about kVA in our blog post. For most applications, a power factor of 0.8 is used. So, if your total load is 80 kW, you’ll need a generator rated at around 100 kVA.

Our calculator takes care of this for you.

Not sure whether you need a single-phase or three-phase generator? Read our guide what is the difference between a single phase and a 3 phase generator to understand the difference and choose the right type for your setup.

Who Should Use a kVA Calculator?

This tool is ideal for:

  • Construction sites and contractors
  • Businesses needing standby or prime power
  • Farms, workshops, and remote operations
  • Homeowners preparing for outages

Whether you're powering tools, servers, or essential appliances, our calculator provides a quick, reliable estimate to guide your purchase.

Why Trust GFE Power Products?

We supply a wide range of dependable diesel generators, backed by expert support and UK-based service. Once you’ve calculated your power needs, our team can help you choose the perfect generator- built for performance, reliability, and long-term value.

Need help? Contact us today for personalised advice.

Disclaimer

Most generator manufacturers rate their generators at a 0.8 power factor (PF). However, in typical UK applications, the electrical load usually operates at unity power factor (1.0 PF), which is more efficient. Historically, rating generators at 0.8 PF results in a higher apparent power output. For example, a 100 kVA generator rated at 0.8 PF will deliver approximately 139 amps per phase. But at unity PF, the same generator delivers only around 112 amps per phase. Because of this, we always recommend selecting a generator that matches or slightly exceeds the actual current (amps) required on-site. This approach provides around 10% headroom, ensuring a more realistic and reliable setup. The calculator above is intended as a general guide. We strongly recommend discussing your specific requirements with an experienced generator specialist.

At GFE, we’re always happy to help, give us a call on 01386 335007.