What Size Generator Do I Need for Camping, Caravans, Blackouts and Worksites

Working out what size generator you need is one sum: rated watts of everything on at once, plus the biggest start-up surge. Campers land near 2kVA, caravan aircon 3kVA, blackout generators 4-5kVA. Check the badge first.

That's the quick answer to what size generator do I need for most jobs. If you want to check it against your own gear, the working is below.

How to Work Out Generator Size - 3 Steps

It's 38 degrees, the power's been out since lunch, and you've dragged the generator out of the shed. You plug in your fridge, the chest freezer and a pedestal fan.

Your fridge compressor kicks in and the whole lot trips. Now you're standing in a dark kitchen wondering if you bought the wrong size.

You probably didn't. Your fridge only needs a couple of hundred watts to keep going. Getting it going is a different job, and that surge is what caught you out.

Three steps sort it. Get them right and your fridge hums along all afternoon while you sit under the fan. If you'd rather skip the sums, the generator finder does them for you.

Step 1 - List Appliance Running Watts

Write down everything you want on at the same time. Then find each one's watts on its compliance plate or in your manual.

Queensland's Electrical Safety Office says to check your appliance's nameplate first. Where you can't find one, it lists typical draws, and those are the figures in this table.

Only got amps on the plate? Multiply by 230, the voltage listed on spec sheets like the Gentech EP20000HSRE's. A 4A appliance draws about 920W.

Better still, put a cheap plug-in energy monitor on your fridge for a day. You'll know what it actually draws instead of guessing.

Step 2 - Add the Biggest Start-Up Surge

Add the surge of your single biggest motor load. Only the biggest, because you won't be switching everything on in the same second.

Fridges, freezers, pumps and aircon compressors all need a hit of extra power for a moment when they kick in. How much extra? The Queensland regulator says motor appliances like fridges and freezers can use up to ten times their listed wattage when starting.

That's why the "add 20 to 30 per cent" advice in some online answers falls short for anything with a compressor.

Owners on Whirlpool have learnt this the hard way. One owner's 1kVA unit kept tripping when a big fridge kicked in, until they switched on a 100W light first to steady it. Pumps can be worse again. One Whirlpool poster puts a pump's surge at up to nine times its motor rating.

Step 3 - Stagger Motor Loads and Leave Headroom

Switch your motor loads on one at a time, a minute or two apart. Once a compressor is running it drops back to its running draw, and the next one gets a clean go.

Then leave some room at the top. A generator sitting on its limit for hours is the one that stumbles when a load kicks back in.

Don't overshoot either. A generator three sizes too big costs you more to buy and more to lug around, and your fridge won't know the difference. How much room is enough gets its own guide on a sensible safety margin.

Rated Watts vs the kVA on the Badge

The number in a generator's name is usually its peak output. The rated figure is its continuous output, what it holds all day, and that's the one to size your gear against.

Across the 19 generators we checked in the True Gear range with consistent spec listings, rated output was a median 82% of the peak figure. 18 of those 19 put the peak figure in the product name.

Take the Hyundai HY2000Si. It's sold as a 2000W generator. It gives you 1,600W rated, with the 2,000W there as a short surge.

kVA badges work the same way. The Westinghouse WHXC5000 wears a 5kVA badge and is rated at 4,000W. Do your sums on the rated figure and you won't get caught short on the day.

Generator Size by Use Case

Here's where most people land, and what shifts your answer.

Camping Generator Size

Usually 1kVA to 2kVA. A few globes, phone chargers, a TV and a fridge together come in well under 1,000W running on the Queensland figures.

A Westinghouse iGen1250 (1,000W rated) covers that. A Hyundai HY2000Si (1,600W rated) gives you room for a smaller microwave on its own.

The catch is your coffee maker. Those same figures put one at 1,750W to 2,400W, which is more than a 1kVA unit can give.

If your weekends are just a fridge and some lighting, a portable power station does that without fuel or engine noise. It's worth a look before you buy a generator you'll barely use. Otherwise, browse the camping generators.

Caravan Generator Size and Air Conditioners

3kVA for most vans with aircon. Your fridge, globes and microwave run fine off 2kVA one at a time, but a rooftop aircon kicking in leaves a 2kVA unit with nothing to spare.

A caravanner on Prospecting Australia spelt it out. Their Honda 2kVA ran flat out on the aircon, while the 3kVA they run now just purrs.

The Westinghouse iGen3750S and the Welling & Crossley WC-P3200Si are both rated at 3,000W. Browse the caravan generators if that's your setup.

2000W Generators and Caravan Aircon

Yes, with conditions. A 2000W generator runs your van's fridge, TV and a small microwave, as long as they're not all on at once.

Aircon is where it gets tight. Commenters on an Adelaide RV video about running aircon on a generator report running caravan aircon off a Honda 2kVA for years. One did it in 55°C heat. Another says it works as long as the 240V hot water is switched off.

Others hit a wall. A commenter on a Searle's RV Centre video says their Honda 2.2 ran the aircon, then couldn't get it going again when the compressor cycled back on.

Check your badge too. A generator sold as 2000W might only give you 1,600W rated. There's more in the guide to running an air conditioner on a generator.

Generator Size for Two Freezers and a Fridge

About 2kW, if you switch them on one at a time. On the Queensland figures each one runs on about 180W, so all three together use around 540W.

The surge is the catch. At about 1,800W each, kicking all three in at the same moment would need more than 5kW.

Stagger them and a 2kW generator copes. One Whirlpool owner runs two fridges and a small upright freezer off a 2,000W non-inverter generator during long outages, plugging them in one after the other. Once all three are going, they share the power fine. The risk they flag is all three compressors cycling on together hours later.

An owner in the Whirlpool thread from Step 2 did something similar after Cyclone Marcia. They kept a fridge and freezer cold through several days without power on a unit of about 2,500W, run on and off through the day.

Plug yours in a few minutes apart and your food stays cold on a much smaller generator than the surge maths suggests.

Home Blackout Generator Size and the 15A Inlet Limit

4kVA to 5kVA for most plug-in blackout setups. Your lead and inlet set the limit before your generator does.

Most home setups run through a 15A inlet and lead. A Whirlpool poster points out that this caps you at about 3.6kW, so a 6kVA generator gains you nothing unless you step up to a 32A inlet. Another poster in that thread would still pick a generator rated for 4kW or more for a steady 3kW load, so it isn't running flat out for hours.

Fitting that inlet and changeover switch is work for a licensed electrician. Energy Safe Victoria is clear on that, and on never running a generator indoors or in an enclosed space. Use leads rated for the current too, because Queensland's regulator warns an ordinary extension cord on a large appliance can overheat.

Sizing a whole house properly is its own job, and the guide to sizing a generator for the whole house runs through it. When you're ready, browse the generators for home.

20kW Generators and Whole-House Loads

There's no house size that fits 20kW. What matters is what you've got switched on. Queensland's figures put a large split system at up to 30,000W starting and 6,000W running, so one of those kicking in is more than a 20kVA generator can give.

Keep your big aircon off or staggered, and 20kVA leaves a lot of room for fridges, lighting and the rest of the house.

The Gentech EP20000HSRE is the biggest petrol generator in the True Gear range. It's 20kVA single phase, with two 32A outlets and a 15A, and a 34-litre tank that uses 6.88 litres an hour at 80% load. It weighs 160kg, so it goes in through a changeover switch fitted by an electrician.

Construction Site Generator Size for Power Tools and Welders

5kVA to 8kVA for a tradie running a few power tools at once. Saws and compressors have the same kick as a fridge, so do the same sums: running watts of what's on together, plus your biggest surge.

The Westinghouse WHXC7000 is rated at 5,500W and the WHXC8500E at 6,750W. On the job you're paying for trade-grade reliability, because a generator that trips halfway through a cut costs you more than the price difference.

A full construction project with sheds and heavy plant is bigger again, and usually a hire job. If your gear runs on three-phase power, you'll need a three-phase generator, like the Gentech ED6800YSRE-3.

For welders, go by the input rating on your welder's plate and treat it as your biggest load. A generator with the welder built in saves you carrying both, and the welding generators are a good place to look.

Not sure what your job draws? Ring the store on 03 7056 6732 and we'll work through it with you.

What a Generator Will Run by Size (1kVA to 20kVA)

Use this table as a starting point. The rated figure is what each unit holds all day, taken from its own product listing.

1kVA to 2kVA Generators

A 2kVA generator runs a fridge on its own. Your fridge surges to about 1,800W, which fits under the Westinghouse iGen2250's 2,250W peak, then settles back to about 180W.

A 1kVA unit is a different story. The iGen1250 peaks at 1,250W, so it may not get a big fridge going at all. That fits with the Whirlpool owner whose 1kVA unit kept tripping.

3kVA Generators

A 3kVA generator runs your caravan aircon with the fridge, or a home fridge, freezer, TV and lighting through a blackout. It won't run the aircon and a coffee maker together.

The Briggs & Stratton P3500 (3.5kVA) is rated at 2,900W and the Westinghouse iGen3750S at 3,000W, so size your gear to those numbers.

5kVA to 8kVA Generators

This is the blackout and small-job band. The Westinghouse WHXC5000 is rated at 4,000W. The WHXC7000 and WHXC8500E step up to 5,500W and 6,750W.

A 6,500W generator will run your home's essentials. Through a standard 15A lead you'll only draw about 3.6kW of it, though, so using the rest means a 32A inlet and changeover fitted by an electrician.

10kVA to 20kVA Generators

Big enough for most of a house or a busy worksite, and big enough to need a proper install. The Champion 12.5kVA is rated at 10,000W. The Gentech EP20000HSRE lists a 20kVA rating with no separate rated watts.

A 10kW generator covers your fridges, lighting and a smaller aircon switched on by itself. A large split system can need up to 30,000W to get going, which is well past 10kW, and the house sizing guide linked above does that maths properly.

Generator Size Verdict

For most people, that's 2kVA for camping, 3kVA for a caravan with aircon, 4kVA to 5kVA for a plug-in blackout setup, and 7kVA or more for tools on the job or a wired-in house. Size against the rated watts of what's on at once, plus your biggest surge.

The exception is fridges and freezers. Switch them on one at a time and a 2kW generator does more than the surge maths suggests. And if you only ever run a fridge and some lighting, a portable power station may suit you better than any generator.

Ring the store on 03 7056 6732 or text 0476 330 590 with your gear list, and we'll size it with you.

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