Measure your tow ball weight
At a weighbridge or with a towball scale.
Weigh the loaded car and van at a public weighbridge, or put a towball scale under the coupling.
Then compare the reading with the lowest towball limit on your car, towbar and towball.
Published . 5 min read • Technical Guide
Weigh the loaded car and van at a public weighbridge in three steps, or put a towball scale under the coupling.
Load the van as you travel, and release any weight-distribution hitch first. Then compare the reading with the lowest towball limit on your car, towbar and towball.
- Common guide - about 10% (of the loaded van's weight)
- Weigh at - a public weighbridge (or with a mobile weighing service)
- Compare with - the lowest towball limit (of the car, the towbar and the towball)
Measure it at a weighbridge
A public weighbridge gives you three weights in one visit. Ball weight is worked out from them.
- Load the car and van as you travel, with water and gear on board. Release any weight-distribution hitch.
- Drive car and van onto the weighbridge together, every wheel on the scale. Note the weight.
- Move so only the car's wheels are on the scale, van still hitched. Note the weight.
- Unhitch the van with its jockey wheel on the scale, and the car off it. Note the weight.
- Take the second reading from the first. That is the load on the van's wheels while hitched.
- Take that load from the third reading. What is left is your ball weight.
A worked example, with made-up numbers
Car and van together weigh 5,000kg. The car alone, van hitched, weighs 2,700kg. So the van's wheels carry 2,300kg. The van alone, on its jockey wheel, weighs 2,550kg. Its ball weight is 2,550kg minus 2,300kg, which is 250kg.
The same visit also checks your other limits. Compare the first reading with the car's GCM (Gross Combination Mass). Compare the second with the car's GVM (Gross Vehicle Mass). Compare the load on the van's wheels with the van's GTM (Gross Trailer Mass). Compare the third with the van's ATM (Aggregate Trailer Mass), and with the lowest tow rating on your car, towbar and towball. Our weighbridge ticket guide explains each line on the ticket. A mobile weighing service can also measure each axle.
Measure it with a towball scale
A towball scale is a gauge that sits under the van's coupling, so you can read the ball weight at home. Follow the scale maker's instructions.
Load the van as you travel before you read it. Release any weight-distribution hitch first. Weigh again whenever you change what you carry, because ball weight changes with packing.
What your reading means
Compare your reading with the towball limit. Your car, your towbar and your towball each have one, and the lowest of the three applies.
- The car's limit is in the owner's manual, in the towing and specifications sections.
- The towbar's limit is on its label.
- The towball's rating is stamped on it.
Ball weight also counts towards the car's GVM, and most of it lands on the rear axle. Our payload calculator shows how much of the car's load it uses.
If the reading is over the lowest limit, repack and weigh again, or ask the van's maker or dealer. A weight-distribution hitch must not be used to correct a ball weight that is too high.
Ball weight as a share of the loaded van
About 10% of the loaded van is a common guide. Western Australia's towing guide says 8 to 10% of the ATM, and the NSW guide says about 5 to 10%.
| Loaded van | At 8% | At 10% |
|---|---|---|
| 1,500kg | 120kg | 150kg |
| 2,000kg | 160kg | 200kg |
| 2,500kg | 200kg | 250kg |
| 3,000kg | 240kg | 300kg |
| 3,500kg | 280kg | 350kg |
These are guides worked out from round weights, not your van's figure. Your real ball weight comes from weighing it. To check a van against your car, use our towing check, or browse caravans by ball weight.
Tow ball weight questions, answered
What should my tow ball weight be?
About 10% of the loaded van is a common guide. Western Australia's towing guide says 8 to 10% of the ATM (Aggregate Trailer Mass). The NSW guide says about 5 to 10%. Whatever the share, compare the reading with the lowest towball limit on your car, towbar and towball.
Is the ball weight on my caravan's compliance plate?
Not necessarily. The van's plate must show the ATM, GTM (Gross Trailer Mass) and tare. It need not show the ball weight. Ask the maker or dealer for the loaded figure, or weigh it.
Why is my ball weight higher than the brochure figure?
Some makers publish the empty van's ball weight. Loaded, it is usually higher. Water, gas and gear all change it, so weigh the van loaded as you travel.
Does ball weight count towards my car's GVM?
Yes. The ball weight presses down on the car, so it counts towards the car's GVM (Gross Vehicle Mass). Most of it lands on the car's rear axle.
Where do I find my car's towball limit?
In the owner's manual, in the towing and specifications sections. The towbar has its own label and the towball has its rating stamped on it. The lowest of the three applies. If the car has a GVM or towing upgrade, its label and certificate show the figures.
Do I release the weight-distribution hitch before weighing?
Yes. Release it before you weigh, so the reading shows the full ball weight. A weight-distribution hitch must not be used to correct a ball weight that is too high.