Easy Steps to Determine Your Generator Needs

You don’t need to be an electrician to figure out the right generator — just follow these simple steps:

  • 1. Enter Your Power Requirements
    Select the appliances, tools, or total wattage you plan to run.
  • 2. Choose Your Application
    Tell us where it’ll be used — home, commercial site, industrial facility, or an event.
  • 3. Get Instant Recommendations
    We’ll calculate your estimated kVA or kW and suggest the best generator size for the job.
  • 4. Explore Rental or Purchase Options
    Based on your result, we’ll show you generator models available to rent or buy.

Generator Size Calculator

  • Calculate kVA, kW, amps, and motor loads
  • Works for homes, construction, and industrial use
  • Designed for Australian power systems

Interactive Generator Sizing Calculator

Power Calculators
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Formula: I = (kVA × 1000) / (V × factor), where factor = 1 (1φ), 2 (2φ, approx), √3 (3φ).

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Formula: kW = kVA × PF.

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Formula: kVA = kW ÷ PF.

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Uses mechanical horsepower: HP = kW × 1.34102.

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This estimator uses rule-of-thumb multipliers (defaults reflect common guidance that ~1 HP ≈ 3–4 kVA to start for DOL; star-delta reduces starting demand). Adjust factors to suit your application. Results are indicative only. :contentReference[oaicite:1]{index=1}

Generator Sizing Guide | How to Choose the Right kVA

Understanding Watts, kVA & Generator Load Requirements

Choosing the right generator isn’t just about picking a number — it’s about matching power supply to your real-world needs. Here’s a quick guide based on common use cases:

Small Homes & RVs

3.5kVA – 6kVA
Enough for essentials like lighting, fridge, and a few appliances.

Large Homes & Small Businesses

8kVA – 15kVA
Great for powering air conditioning, tools, or multiple appliances at once.

Construction Sites & Industrial Use

20kVA – 100kVA+
Suitable for machinery, welders, compressors, and job site equipment.

Heavy-Duty Power Needs

100kVA – 500kVA
Ideal for factories, remote operations, and large-scale commercial facilities.

Determining the Best Generator for Your Needs

Factors to Consider When Choosing a Generator

Not all generators are built the same — and not all power needs are equal. Here’s what to think about before you choose:

Power Load

What exactly do you need to run? A few lights and a fridge? Or welders, compressors, and heavy machinery? The total wattage makes all the difference.

Fuel Type

Diesel is reliable and fuel-efficient for big jobs. Petrol works well for portable and lighter-duty setups. Battery and hybrid options are growing too — especially for eco-conscious sites.

Standby vs. Prime Power

Do you need backup for emergencies (standby)? Or is this your main power source (prime)? We’ll help you match the right generator for your usage pattern.

Portability

Will the generator stay put, or do you need it to move between locations? We offer stationary units, trailer-mounted options, and fully portable models.

Whether you're powering a food truck or an entire factory, our team can help you make the right call — no guesswork required.

Speak to a Generator Expert

3 Phase Generator Sizing Calculator

Three-phase generators are typically used when higher power loads are required. This includes commercial buildings, construction sites, industrial equipment, and any setup running large motors or multiple systems at the same time.

If your site uses heavy machinery, pumps, compressors, or large HVAC systems, a three-phase generator is usually the right choice. These systems provide more stable and efficient power distribution compared to single-phase setups.

To calculate the correct size, use the inputs in the calculator above. Select three-phase power, enter your voltage and load requirements, and the tool will estimate the kVA needed based on your setup.

This gives you a quick and practical way to size a generator accurately before choosing equipment.

Not sure where to start? Read our detailed guide on what size generator do you need.

How do I calculate what size generator I need?

You can use our free power requirement calculator to get an instant recommendation. Just enter your appliances, power usage, and application — we’ll do the rest.

What size generator do I need to run my house?

Most homes require somewhere between 5kVA and 10kVA, depending on what you need to power. Bigger homes with air conditioning, pumps, or multiple fridges may need up to 15kVA or more.

What does kVA mean in generator sizing?

kVA stands for kilovolt-amperes — it’s a measure of the total capacity of your generator. It differs from kW, which measures usable power. Most home and business generators fall between 5kVA and 100kVA.

What size generator do I need for my business?

It depends on your equipment and peak power usage. Office spaces typically need 10–20kVA. Construction and industrial sites may require 50kVA or more. Use our calculator or contact our team for tailored advice.

Generator Sizing Made Simple — Backed by Experts

Whether you need power for your home, business, or worksite, SGH makes it easy to get the right fit. Use our free calculator, or speak to our team for expert advice.

Let’s help you avoid overspending — or under powering — and get it right the first time!

Need Help Choosing the Right Generator?

✔ Instant size estimates with our generator calculator
✔ Options for diesel, petrol, battery & hybrid setups
✔ Rent or buy the generator that fits your needs
✔ Expert support available across Australia

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