How do I work out my caravan's payload?

Subtract the tare mass from the ATM, both from the caravan's compliance plate. That's the payload on paper. Then subtract anything fitted after the tare was plated, water in the tanks, gas and everything you pack.

Does water in the tanks count as payload?

Yes. Water weighs about 1 kg per litre, so two full 80 litre tanks add about 160 kg. Many people travel with tanks partly empty and fill up near camp.

Is the tare on my caravan's plate accurate?

It should match the van as built, but options and accessories fitted afterwards, by the dealer or by you, aren't included. Batteries, solar panels, annexes and a second spare can add a lot. Weighing the empty caravan at a weighbridge tells you its real starting weight.

What happens if my caravan is over its ATM?

Being over the ATM breaks the trailer's rated limit, can affect your insurance, and can overload the axle, tyres and coupling. Reduce the load or check whether the manufacturer offers a re-rating.

Caravan payload calculator (ATM minus tare)

How it's worked out

Payload = ATM − tareRemaining = payload − extras − water − gas − gear

VSB 1, the national standard for light trailers, requires the caravan's plate to show its ATM, GTM and tare mass. The ATM is the most the loaded caravan may weigh on its own. Tare is the caravan as delivered, ready for service, with no load.

Worked example

A caravan plated at 3,000 kg ATM and 2,450 kg tare has 550 kg of payload. Take off 60 kg of extras added after delivery, 160 kg of water, 36 kg of gas and 200 kg of gear, and 94 kg is left. Emptying one 80 litre water tank would free up about 80 kg.

Two more limits to check

GTM. The weight on the caravan's axles (ATM minus towball download) must stay under the plated GTM.
Your tow vehicle. A caravan within its own ATM can still be too heavy for the vehicle pulling it. Check with the towing calculator.

Common questions

How do I work out my caravan's payload?: Subtract the tare mass from the ATM, both from the caravan's compliance plate. That's the payload on paper. Then subtract anything fitted after the tare was plated, water in the tanks, gas and everything you pack.
Does water in the tanks count as payload?: Yes. Water weighs about 1 kg per litre, so two full 80 litre tanks add about 160 kg. Many people travel with tanks partly empty and fill up near camp.
Is the tare on my caravan's plate accurate?: It should match the van as built, but options and accessories fitted afterwards, by the dealer or by you, aren't included. Batteries, solar panels, annexes and a second spare can add a lot. Weighing the empty caravan at a weighbridge tells you its real starting weight.
What happens if my caravan is over its ATM?: Being over the ATM breaks the trailer's rated limit, can affect your insurance, and can overload the axle, tyres and coupling. Reduce the load or check whether the manufacturer offers a re-rating.

Sources

Vehicle Standards Bulletin 1 (Revision 6): trailers with an ATM of 4.5 tonnes or less (August 2026), Australian Government, Department of Infrastructure
Towing a trailer or caravan, NSW Government (Transport for NSW)

Rules checked against these sources on 12 October 2026. See rules, sources and method.