Caravan weights can feel like alphabet soup: ATM, tare, GTM, GVM, GCM, ball weight and payload. But if you are buying a camper in Australia, these numbers decide whether your setup is legal, safe and comfortable to tow.
The Main Caravan Weight Terms
| Term | Plain-English meaning | Why buyers care |
|---|---|---|
| Tare | Approximate empty trailer weight | Starting point before gear, water and accessories |
| ATM | Maximum loaded trailer weight when not coupled | The loaded camper must not exceed this |
| GTM | Loaded trailer weight on its wheels when coupled | Used with tow vehicle limits and axle loading |
| Tow ball weight | Weight transferred onto the vehicle towball | Counts against vehicle/towbar limits and payload |
| Payload | How much you can add after tare | Gear, water, food, gas and accessories all count |
Payload Is Usually the Number Buyers Underestimate
Payload is the difference between tare and ATM. If a camper has a low payload, it can become overloaded quickly once water, recovery gear, food, bedding and accessories are added.
JAG publishes practical weights because buyers need to do this maths before they commit. The JAG Glider is designed around a light starting point so buyers have more room to match the camper to smaller cars, compact SUVs and EVs.
Simple Weight Calculation
| Item | Example impact |
|---|---|
| Water | 1 litre is roughly 1kg |
| Gas bottle | Counts toward loaded trailer mass |
| Fridge contents and food | Adds up quickly on longer trips |
| Tools and recovery gear | Often heavier than expected |
| Aftermarket accessories | Can reduce remaining payload |
Do Not Only Read the Brochure
The safest approach is to check the compliance plate, vehicle manual and towbar rating, then weigh the loaded setup when possible. RACQ explains that ATM is the combined trailer and full load when not coupled, while GTM is the loaded trailer weight imposed on the axle when coupled.
That distinction matters because some trailer weight transfers to the tow vehicle through the tow ball. In real life, both the car and trailer need to stay inside their limits at the same time.
Quick Answers
What is ATM on a caravan?
ATM is Aggregate Trailer Mass. It is the maximum weight of the trailer and everything loaded into it when the trailer is not coupled to a tow vehicle.
What is tare weight on a caravan?
Tare is the trailer’s approximate empty weight before luggage, water, food, gas and accessories are added.
How do I calculate caravan payload?
Payload is generally ATM minus tare. Everything you add to the camper after tare uses payload.
If you want a lightweight starting point, compare the JAG Glider and JAG’s other teardrop camper information before matching a tow vehicle.
