kW vs kVA: What’s the Difference?
When planning temporary power for an event, festival or a shutdown, it’s easy to overlook the finer technical details – but understanding the difference between kW (kilowatts) and kVA (kilovolt-amperes), can save you from costly errors, underpowered setups and safety concerns.
At Event Sparks, we’re regularly asked about this difference. This guide’ll break it down clearly so you can confidently choose the right generator for your needs and avoid under- or over-specifying your power.
What’s the Difference Between kW and kVA?
The main difference between kW and kVA comes down to power efficiency.
- kW (kilowatts) refers to the real power – the actual usable power that can perform work (e.g lighting, sound systems or refrigeration).
- kVA (kilovolt-amperes) refers to apparent power – the total power supplied by a generator, including both usable and wasted energy (due to inefficiencies like heat or resistance in electrical systems).
Think of it like this: if your generator is pouring water into a machine, kW is the water doing the work, and kVA is the total amount of water poured, including the bit that leaks or evaporates.
The Role of Power Factor
To convert kVA to kW, you multiply by the power factor, a number between 0 and 1 that represents system efficiency.
In most generator setups, especially for events and construction sites, the standard power factor is 0.8.
Formula:
kW = kVA x Power Factor
Example:
If you’re using a 100kVA generator with a power factor of 0.8, the real power available is:
100kVA x 0.8 = 80kW
This means you have 80kW of usable power, and that’s what your equipment will actually draw on.
Why This Matters for Event Planners
Whether you’re powering a multi-stage music festival, a college open day or a private event, knowing your real needs in kW helps ensure:
- You don’t overload the generator (which can trip the supply or damage equipment)
- You don’t over-specify and waste money on an oversized unit
- Your site runs efficiently and safely, with no surprise outages
Understanding the kW vs kVA difference helps you communicate clearly with your supplier and make informed decisions when hiring temporary power.
When Should You Use kW vs kVA?
- Use kW when estimating your equipment or site’s total load (e.g lighting, pa and band power requirements).
- Use kVA when selecting or hiring a generator, because that’s how most generators are rated.
Need Help Calculating Your Power Needs?
If you’re unsure about how to convert your site’s equipment list into real power requirements – or you just want someone to double-check your numbers – we’re here to help.
At Event Sparks, we help our clients plan their temporary power setups around real-world needs, not just technical specs. That means:
- We ask the right questions up front: What’s your total load? What type of equipment is running? Will loads spike at certain times?
- We always build headroom for safety and reliability.
- We help explain the difference between kW and kVA so you feel confident in your hire.
Ready to get started? Speak to our team today or request a quote, and we’ll help you find the right generator for your event, based on exactly what you need!
