What Size Generator Do I Need?

When you’re planning an event, whether it’s a high-energy music festival or a an important private event,, there is one invisible guest that can make or break the day: power.

If you've spent any time looking at generator hire, you’ve likely seen terms like "kVA," "kW," and "three-phase". It can feel like you need an engineering degree just to turn the lights on. But getting your power requirements right is about more than just avoiding a blackout—it’s about ensuring the safety, professionalism, and atmosphere of your event.

At JTHire, we provide everything from compact 20kVA units for small tasks to powerful 60kVA+ diesel generators for large-scale operations. Here is our straightforward guide to help you calculate exactly what you need.

1. The Golden Rule: List Your "Peak Load"

To find the right size, you must first identify every piece of equipment that will be running simultaneously. This includes:

Sound & Stage: Speakers, amplifiers, and monitors.
Lighting: Stage rigs, festoons, uplighters, and safety lighting.
Catering: Coffee machines, fryers, and (crucially) refrigeration.
Infrastructure: Luxury toilet trailers, heaters, and laptop charging stations.

Pro Tip: Check the labels on your gear for the Wattage (W) or Amps (A). If you have the total Watts, divide by 1,000 to get the Kilowatts (kW).

2. Understanding kVA vs. kW

Generators are typically rated in kVA (kilovolt-amps). For most mobile generators, there is a "power factor" of 0.8. This means a 10kVA generator actually provides about 8kW of usable power.

Always ensure your kVA rating is higher than your total kW requirement to avoid overloading the system.

3. Factor in the "Surge"

Items with motors, like fridges, air conditioning, or power tools, require a massive "surge" of energy just to start up, often 3 to 5 times their regular running power. If your generator is sized too strictly, that initial "kick" could trip the entire system.

We recommend always adding a 20–30% safety buffer to your total calculation to handle these surges and unexpected additions.

Typical Hire Sizes by Event Type

Why Choose JTHire for Your Power?

We don't just drop off a box and leave you to it. We specialize in complete festival packages, meaning we can coordinate your generator hire alongside your stage, sound, and lighting for a seamless, professional experience.

Quiet & Efficient: Our modern diesel generators are silenced, making them ideal for weddings and residential areas.
Reliable Support: From rapid delivery in Leicester to professional setup, we ensure your event stays powered from the first speech to the final encore.

Need help with the math?

Don't risk a mid-event blackout. Contact the team at JTHire today, and we’ll help you spec the perfect power solution for your next project.

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Meta Description - Unsure on what size generator you need? Use our helpful guide to calculate power requirements and learn how kVA ratings affect your event's success.