Buy too small, and your generator trips out the moment you flick the kettle on. Buy too big, and you’re hauling dead weight through the bush for power you’ll never use. The difference between a comfortable off-grid camp and a frustrating one often comes down to a single decision: choosing the right wattage.
Sizing an inverter generator isn’t complicated, but it does require a bit of honest math. You need to know what you’re powering, how many appliances will run simultaneously, and whether any of them draw a heavy surge on startup. This guide walks through the calculation step by step, then matches common Australian camping setups to the generator size that fits. Whether you’re charging a phone at a beach picnic or running a caravan air conditioner in 40-degree heat, Outbax’s Gentrax range covers every scenario from 800W to 4.2kW.
Why Generator Sizing Matters for Off-Grid Camping
The Cost of Getting It Wrong
An undersized generator doesn’t just fail to keep your fridge cold. When you exceed its rated output, the unit overloads, shuts down, and can damage both the generator and the appliance plugged into it. Do that repeatedly and you’ll shorten the engine’s lifespan well before its time.
Oversizing carries its own penalty. A 4kW unit burning fuel at a campsite where 2kW would suffice means extra weight in the vehicle, higher fuel costs, and noise you didn’t need. The goal is to land in the middle — enough headroom for comfort without excess.
Rated Watts vs Surge Watts Explained
Every generator has two wattage figures. Rated (or running) watts is the continuous output the unit can sustain for hours. Surge (or starting) watts is the brief spike it can handle when a motorised appliance kicks in — a fridge compressor, for instance, may draw two to three times its running wattage for the first second or two. When sizing your generator, always work from the rated watts figure. That’s your real-world ceiling.
How to Calculate Your Camping Power Needs
Listing Your Essential Camping Appliances
Start by writing down every electrical item you plan to take. Be specific. A 12V camping fridge typically draws 40-60W running. LED camp lights sit around 10-20W. Phone and tablet chargers pull 10-25W each. A laptop charger needs roughly 60-90W. A CPAP machine runs at about 30-60W, depending on the model. A microwave will need 600-1,200W. And a caravan rooftop air conditioner — the big one — draws anywhere from 1,500W to 2,500W running, with a startup surge considerably higher.
Adding Up Your Total Wattage Requirements
Once you have your list, add the running wattage of every appliance you’d realistically use at the same time. This is your baseline load. Then identify the single appliance with the highest startup surge and add that surge figure on top. For most camping setups, the fridge compressor or the air conditioner will be the surge culprit.
Building in a Safety Margin
A generator running constantly at 100% rated output won’t last. It’s louder, less fuel-efficient, and under more mechanical stress. Add a 15-20% buffer above your calculated total. If your maths lands at 2,800W, a 3,500W-rated generator gives you the breathing room for comfortable, quiet operation. That margin also leaves space for the odd appliance you didn’t plan for — a hair dryer on a cold morning, a power tool for a quick repair.
Matching Inverter Generator Size to Your Camping Style
Day Trips, Picnics, and Ultra-Light Camping (Under 1,000W)
If your kit list is a phone charger, a Bluetooth speaker, a laptop, and maybe a small fan, you don’t need much. An 800W inverter generator like the Gentrax GT800 weighs just 8.5kg — light enough to carry one-handed. It’s a genuine pocket power plant for picnics, beach days, market stalls, or anyone running a CPAP machine at a campsite. Pure sine wave output means it’s safe for sensitive electronics like drones, cameras, and laptops without risk of voltage damage.
Here’s what one of our customers said about the GT800:
“Great little backup unit for off grid camping and as a quiet 230v source for lighting etc on photography shoots. Light, economical, quiet, great value. Combine it with a quality battery charger and you can rescue/start big vehicles/4wds.”
Weekend Tent Camping and Fishing Trips (2,000W)
A step up covers the weekend warrior. With 2kW of rated power, you can comfortably run a camping fridge, a set of LED lights, a phone charger or two, and still have headroom for a small appliance like a toaster or blender. The Gentrax GT2000 hits this mark at 18.5kg with fuel efficiency of up to six hours at 50% load — enough to get through an entire night on a single tank. It fits in a car boot without eating into your gear space, making it a practical choice for multi-person tent camping and fishing weekends.
Caravan Touring and Extended Off-Grid Stays (3,500W–4,200W)
This is where most Australian caravan owners land. Running a rooftop air conditioner on a 38-degree day in outback Queensland demands serious wattage, and anything below 3,500W rated simply won’t cope with the startup surge.
The Gentrax GT3500 delivers 3.5kW in a remarkably compact 28kg frame — exceptionally light for this power class. It handles air conditioners, microwaves, fridges, and multiple smaller appliances simultaneously, which makes it the all-rounder for standard caravan touring and home storm backup.
For heavier setups — farms running water pumps, multiple caravans on a single supply, or biocycle systems — the Gentrax GTX4200 Pro pushes to 4.2kW rated output. At 41.5kg, it’s heavier, but built-in wheels and remote start make it manageable. It’s widely used as a semi-permanent power plant on rural properties as much as it is for camping.
Beyond Wattage: Noise, Weight, and Fuel Efficiency
Keeping It Quiet at the Campsite
Inverter generators are significantly quieter than conventional open-frame models. Where a standard generator might sit at 75-80 decibels, a quality inverter unit typically operates between 52-62dB at rated load — roughly the volume of a normal conversation. That matters at Australian campgrounds, where noise restrictions are common, and your neighbours are often just metres away. The enclosed casing and variable engine speed of an inverter generator keep noise levels low, especially at partial loads.
Portability for Remote Camping in Australia
Weight-to-power ratio is a genuine consideration when you’re packing a 4WD for a week in the Kimberley or driving unsealed roads through the Victorian High Country. The 8.5kg GT800 tucks anywhere. The 28kg GT3500 is still manageable for two people to lift into a vehicle. For heavier units like the GTX4200 Pro, the integrated wheel kit and folding handle mean one person can roll it into position without straining their back.
Here’s what one of our customers said about the GTX4200 Pro:
“Great generator, just used it at an event to run the equipment on a food stand with a fridge and 2 baine maries all day and didn’t miss a beat.”
Fuel Consumption and Runtime
Fuel efficiency scales with load. Running a generator at 25%-50% of its rated capacity is the sweet spot for economy and engine longevity. The GT2000’s six-hour runtime at half load is a standout figure — it means fewer fuel stops and less jerry can storage on extended trips. Larger units consume more fuel, but the trade-off is capacity to run high-draw appliances that smaller generators simply can’t handle.
Choosing the Right Outbax Inverter Generator for Your Next Trip
Quick-Reference Sizing Summary
Match your camping style to a wattage tier: under 1,000W for day trips and device charging (GT800), 2,000W for weekend tent camping and fishing (GT2000), 3,500W for caravan touring and air conditioning (GT3500 or GTX3500), and 4,200W for heavy-duty setups and farm use (GTX4200 Pro). If you’re unsure, calculate your total appliance load using the method above and add the 20% buffer.
Features That Make the Difference: Pure Sine Wave, Remote Start, and Wheels
Every Gentrax inverter generator produces pure sine wave power, which is essential for safely charging sensitive electronics. Higher-tier models add remote and key start for convenience — particularly useful on cold mornings or when the generator is positioned away from your campsite. Wheeled models like the GTX3500 and GTX4200 Pro trade a few extra kilograms for genuine ease of transport around large campsites or worksites.
Find Your Ideal Camping Generator Size
The right inverter generator for camping comes down to three things: what you’re powering, how you travel, and how much weight you’re prepared to carry. Run the wattage calculation, add a sensible buffer, and match it to the tier that fits your setup.
Outbax’s Gentrax range spans every camping scenario from ultra-light day trips to heavy-duty caravan touring. Browse the full collection at outbax.com.au to find the model that fits your next adventure.
