Towing Payload Calculator
Work out how much payload capacity your tow vehicle has left after passengers, gear, accessories and the trailer's tow-ball download. Overloading a vehicle past its GVM is illegal, voids insurance and ruins braking and handling — this calculator shows at a glance whether you are inside or over the limit.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the vehicle's GVM rating and kerb mass from the compliance plate or handbook.
- Add the total weight of occupants plus cargo you carry, and optionally any fitted accessories (bullbar, canopy, drawers) and the trailer's tow-ball download.
- Read the remaining payload and verdict — a negative result means you are over the GVM and must shed weight.
How it works
Remaining payload = GVM − kerb mass − occupants/cargo − accessories − tow-ball download. The tow-ball download is included because the ball weight of the trailer bears down on the tow vehicle and eats into its payload just like any other load. If the sum of everything added exceeds GVM − kerb mass, the payload goes negative and the vehicle is over its legal Gross Vehicle Mass.
Worked example
Worked example. A ute has a GVM of 3000 kg and a kerb mass of 2300 kg. With 300 kg of occupants and cargo, 100 kg of accessories and a 200 kg tow-ball download, the total load added is 600 kg. Remaining payload = 3000 − 2300 − 600 = 100 kg, so it is within GVM but only just.
Common mistakes
- Forgetting the tow-ball download — it can be 150–350 kg and counts fully against the tow vehicle's payload, not the trailer.
- Using the maximum GVM but a light-spec kerb mass; accessories and a full fuel tank raise kerb mass, cutting real payload.
- Assuming payload and towing capacity are the same thing — payload is about the vehicle's own GVM, separate from GCM and tow rating.
Frequently asked questions
Does the tow-ball download really reduce my payload?
Yes. The download from a coupled trailer presses on the tow vehicle's rear, so it must be counted as part of the load carried within GVM. A heavy caravan with a 250 kg ball weight uses 250 kg of the tow vehicle's payload before you add a single passenger.
Where do I find my GVM and kerb mass?
GVM is on the vehicle's compliance/build plate and in the owner's handbook. Kerb mass is the vehicle's ready-to-drive weight with fluids but no occupants or cargo — the handbook lists a figure, but the most reliable number comes from weighing your actual vehicle at a public weighbridge.
Related tools
- GVM & GCM Compliance Calculator
- Caravan Tow Safety (85% Rule) Calculator
- Fuel Consumption Calculator
- Road Trip Fuel Stop Calculator
- Trailer Tongue Weight Calculator
- Service Interval Calculator
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Tip: Enter any known values to calculate the remaining results.
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