Max allowed weight of vehicle including passengers, payload & towball mass.
kg
Max total weight of car and caravan combined.
kg
Manufacturer rated towing limit.
2. Load & Caravan Details
kg
Total weight added to the car (excluding tow ball).
kg
Total weight of the caravan fully loaded.
kg
Weight pressing down on the tow ball (usually ~10% of ATM).
Towing Safety Status
Calculating…
Formula: Compares Actual Mass vs Limits (GVM, GCM, Towing Cap)
Remaining Vehicle Payload
0 kg
Available before exceeding GVM
Remaining GCM
0 kg
Available before exceeding Combo Limit
Towing Capacity Utilization
0%
Of Max Towing Limit
Weight Limits vs. Actuals
Metric
Limit (kg)
Actual (kg)
Status
Vehicle Weight (GVM)
–
–
–
Combination Weight (GCM)
–
–
–
Towing Load
–
–
–
Complete Guide to the Caravan Towing Weights Calculator
Ensuring your vehicle and caravan setup is legal and safe is critical for any road trip. Overloading not only voids your insurance and invites heavy fines but also significantly increases the risk of accidents. This caravan towing weights calculator helps you understand the complex relationship between GVM, GCM, and payload to keep you safe on the road.
What is a Caravan Towing Weights Calculator?
A caravan towing weights calculator is a specialized tool designed to verify if your vehicle is legally capable of towing your caravan. Unlike simple subtraction, towing mathematics involves multiple interdependent limits. Increasing your caravan's weight might push your car over its Gross Combination Mass (GCM) limit, or a heavy Tow Ball Mass (TBM) might overload your vehicle's rear axle (GVM).
This tool is essential for:
Caravan owners planning a trip.
Buyers looking to match a new caravan to their existing vehicle.
Drivers ensuring compliance with local transport regulations.
Common Misconception: Many drivers believe if their car has a "3500kg towing capacity," they can tow a 3500kg caravan while the car is fully loaded. In reality, the Gross Combination Mass (GCM) often limits this, forcing you to reduce the weight in the car to tow the full capacity.
Towing Formulas and Explanations
To use this caravan towing weights calculator effectively, you must understand the key variables defined below.
Acronym
Full Name
Definition
GVM
Gross Vehicle Mass
Maximum allowable weight of the vehicle on its 4 wheels. Includes fuel, passengers, cargo, AND Tow Ball Mass.
GCM
Gross Combination Mass
Maximum allowable combined weight of the vehicle and the caravan.
ATM
Aggregate Trailer Mass
Total weight of the caravan unhitched (weight on wheels + weight on jockey wheel).
TBM
Tow Ball Mass
The weight the caravan coupling applies to the vehicle's tow ball.
Kerb Weight
Kerb Weight
The weight of the empty vehicle with a full tank of fuel but no passengers or cargo.
The Calculation Logic
The mathematics behind a safe towing setup involves three primary checks:
Towing Capacity Check:Caravan Loaded Weight (ATM) ≤ Max Towing Capacity
GCM Check:(Actual Vehicle Weight + Actual Caravan Weight) ≤ GCM Limit Note: In GCM calculations, do not double count the TBM. The combination mass is simply the total mass of the car plus the total mass of the trailer.
Practical Examples of Towing Weights
Example 1: The "Safe" Setup
Vehicle: Modern 4×4 Dual Cab. GVM Limit: 3100 kg | GCM Limit: 6000 kg. Scenario: You load the car to 2800 kg (including TBM) and tow a 2500 kg caravan.
Vehicle Check: 2800 kg < 3100 kg (Safe)
Combination Check: 2800 + (2500 – TBM adjustment not needed for total mass sums) = 5300 kg total rolling mass. < 6000 kg (Safe).
Result: Green light. You have payload and GCM buffer.
Example 2: The "GCM Trap"
Vehicle: Same 4×4. Scenario: You tow the maximum rated 3500 kg caravan. This leaves you with (6000 – 3500) = 2500 kg for the vehicle.
If your vehicle's Kerb weight is 2200 kg, you only have 300 kg left for passengers, fuel, bullbars, and the tow ball mass itself.
If TBM is 350kg, your car is already at 2550 kg before you even get in!
Result: Illegal. Even though the car is rated to tow 3500 kg, it cannot do so while carrying passengers without exceeding GCM.
How to Use This Caravan Towing Weights Calculator
Enter Vehicle Specs: Find your GVM, GCM, and Kerb weights on your vehicle's compliance plate or owner's manual.
Estimate Loads: Add up the weight of passengers, roof racks, fridges, and luggage in the car. Be realistic—most people underestimate this.
Enter Caravan Details: Input the actual weight of your loaded caravan. Do not rely on the "Tare" weight stamped on the plate; caravans are almost always heavier once water, gas, and clothes are added.
Check Results: Look at the "Safety Status." If it is red, check which limit you have exceeded (GVM, GCM, or Tow Capacity) in the table below the chart.
Key Factors That Affect Towing Results
Several variables can drastically alter your caravan towing weights calculator results:
Aftermarket Accessories: Bullbars, winches, and canopy setups reduce your available payload significantly.
Water Tank Levels: Carrying 200L of water adds 200kg to your caravan mass instantly.
Tow Ball Mass Distribution: A heavy TBM improves stability but eats into your car's GVM. A light TBM reduces GVM stress but causes trailer sway. Aim for 10% of ATM.
Passengers: Four adults can weigh 350kg+, reducing your ability to carry camping gear.
Axle Loading: Even if you are under GVM, you must ensure you haven't exceeded the maximum Rear Axle Load Rating.
Fuel Weight: A long-range tank (140L) adds over 110kg to your vehicle's weight compared to empty.
Frequently Asked Questions (FAQ)
Does Tow Ball Mass count towards GVM?
Yes. The weight pushing down on the tow ball is supported by the vehicle's suspension, so it must be included in the Gross Vehicle Mass (GVM) calculation.
Can I increase my GVM?
Yes, GVM upgrades are available via certified suspension modifications. However, this often does not increase your GCM, meaning you can carry more in the car but tow less.
What happens if I exceed my GCM?
It is illegal and unsafe. You risk fines, voided insurance, and mechanical failure (brakes/transmission overheating).
Is GCM simply GVM + Max Towing Capacity?
Rarely. Most modern Utes have a GCM that is less than the sum of GVM and Tow Capacity. This is why the caravan towing weights calculator is vital.
How do I weigh my setup accurately?
Use a public weighbridge. Weigh the car alone, the car with caravan attached, and the caravan alone (unhitched) to get all accurate figures.
What is the difference between Tare and ATM?
Tare is the empty weight of the caravan. ATM is the maximum legal weight fully loaded. Payload is ATM minus Tare.