What should my towball weight be?

There is no single legal percentage. Transport for NSW suggests about 5 to 10% of the loaded trailer's weight, NRMA says roughly 10 to 15%, and 10% is a common planning figure. The legal limits are your vehicle's maximum towball download and your towbar's rating, which you must not exceed.

Is too little towball weight dangerous?

A trailer that's light on the towball is more prone to sway. If your figure is low, move heavy items forward of the trailer's axle rather than to the rear.

How do I measure towball download?

Use a towball weight scale under the jockey wheel or coupling, or a weighbridge: weigh the vehicle with the trailer hitched (trailer wheels off the bridge), then the vehicle unhitched. The difference is the towball download.

Is towball download the same as ball weight or tongue weight?

Yes. Towball download, towball mass (TBM), ball weight, nose weight and tongue weight all mean the downward weight the trailer puts on the towball.

Towball weight calculator

The formula

Towball % = towball download ÷ loaded trailer weight × 100

For a 2,500 kg caravan with 230 kg on the ball: 230 ÷ 2,500 × 100 = 9.2%. At 10% the same caravan would put 250 kg on the ball.

What the guidance says

Source	Guidance
Transport for NSW	About 5 to 10% of the total mass of the trailer plus load
NRMA	Roughly 10 to 15% (of GTM)
Your vehicle and towbar	A hard maximum in kg. This is the limit you must stay under.

The percentages are guidance about stability, not legal limits. The calculator marks anything under 5% as light and anything over 15% as heavy, because those are the edges of the published ranges.

How to change your towball download

Too light: move heavy items such as tools, water and food forward of the axle, or carry water in a front tank.
Too heavy: move weight back toward the axle, empty front water tanks, or take items off the A-frame such as bikes or a second gas bottle.
Keep heavy items low and close to the axle. NSW suggests about 60% of the trailer's weight should sit forward of the axle centre.

Changing towball download also changes how much of your vehicle's GVM you're using. Check the whole setup with the towing calculator.

Common questions

What should my towball weight be?: There is no single legal percentage. Transport for NSW suggests about 5 to 10% of the loaded trailer's weight, NRMA says roughly 10 to 15%, and 10% is a common planning figure. The legal limits are your vehicle's maximum towball download and your towbar's rating, which you must not exceed.
Is too little towball weight dangerous?: A trailer that's light on the towball is more prone to sway. If your figure is low, move heavy items forward of the trailer's axle rather than to the rear.
How do I measure towball download?: Use a towball weight scale under the jockey wheel or coupling, or a weighbridge: weigh the vehicle with the trailer hitched (trailer wheels off the bridge), then the vehicle unhitched. The difference is the towball download.
Is towball download the same as ball weight or tongue weight?: Yes. Towball download, towball mass (TBM), ball weight, nose weight and tongue weight all mean the downward weight the trailer puts on the towball.

Sources

Towing a trailer or caravan, NSW Government (Transport for NSW)
How much is your vehicle designed to carry or tow?, NRMA

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