Towing Weights Calculator

Got a trailer or caravan? Want to know if your weights are within limits? This tool is what you need!

Just enter a few measurements below and you can:

• Work out if your car can tow a given trailer or caravan;
• See the heaviest trailer or caravan your car or 4×4 can tow;
• Work out how much payload you have left once your trailer is attached;
• See how close you are to limits such as GVM, max tow, payload and GCM;
• Understand your trailer weights and get basic trailer weight advice;
• NEW as of 24/10 – check front and rear axle weights, a common limit to run uo against!

The calculator assumes you are familiar with terms like GVM, GCM and TBM. If you’re not, then please read this first, then come back here.

You can use metric measurements or imperial, as the calculations are the same.

If you are familiar with towing weights, then here’s some explanatory notes about the calculator.

Calculator results are for guidance only – final checks should be made using all the data and limitations specific to your towcar and trailer which this calculator may not cater for.

Enter your trailer and towcar details below
Your reference: Whatever you want to name this calculation, e.g. "Ford Ranger and DreamVan". Not used in calculations. Only a-Z, 0-9 and - allowed.
Trailer
Actual trailer weight		Measure this; trailer ready to tow, including TBM; this should be equal to or less than the trailer's ATM.
Trailer ATM		Maxium weight of trailer; refer to trailer placard. The ATM should be equal to or more than the trailer's actual weight.
Towball mass (TBM)		Measure this; as ready to tow. If you can't measure it, use 10% of trailer weight.
Towcar
Actual towcar weight		Measure this; towcar ready to tow but unhitched; accessories, luggage, people, fuel etc. This should be less than the towcar's GVM.
Towball mass (TBM) limit		The maximum TBM. Look on towcar's placard, towbar, and tow tongue; use the lowest figure of the three.
Max tow capacity		Refer to vehicle specs. Maximum braked towing capacity.
GVM		Gross Vehicle Mass. Refer to your vehicle's weight placard.
GCM		Gross Combination Mass. Refer to vehicle's specs.
Rear axle limit data (optional)
Wheelbase		Distance between front and rear wheel centres. Refer to vehicle's specs.
Overhang		Distance between rear wheel centre and towball. You will need to measure this!
Rear axle load limit		Maximum load on rear axle. Refer to vehicle's specs. Use 0 if not known.
Front axle load limit		Maximum load on front axle. Refer to vehicle's specs. Use 0 if not known.
% of weight on rear axle		Measure using scales when ready to tow, or use 60% as a guess.
Email: Leave blank unless you want results emailed to you. Email not stored or used for any other purpose.
Calculate

 

Results
Trailer and towcar details
Total trailer weight	2500	The weight of your trailer, as ready to tow, including TBM.
Towball mass (TBM)	250	Usually around 10% of trailer weight.
Towcar weight	2600	Weight of your towcar, as ready to tow.
Max tow capacity	3000	Maximum braked tow capacity of your towcar.
GVM	3100	Gross Vehicle Mass of your towcar.
GCM	6000	Gross Combination Mass of your towcar.
Front axle limit	0	Maximum weight permitted on front axle.
Rear axle limit	0	Maximum weight permitted on rear axle.
Wheelbase	3000	Distance between centre of front and rear wheels
Overhang	1500	Distance between centre of rear wheels and centre of towball
Towing weight calculations - guidance only
Combined weight towcar & trailer:	5100	Towcar & trailer combined, ready to tow. This must not be greater than the GCM.
Percentage of trailer weight to towcar weight:	96 %	The lighter the trailer relative to the towcar the better, ideally this would be less than 100%.
Margin to ATM:	500	You are within the ATM of 3000 by 500.
TBM as a percentage of trailer weight:	10 %	Towball mass (TBM) of your trailer; weight on the towball.
Rear axle load, approx (1):	0	Axle limits not given, but based on wheelbase/overhang, rear axle load increases by 375.
Front axle load, approx (1):	0	Axle limits not given, but based on wheelbase/overhang, front axle load decreases by 125.
Margin to max TBM:	50	How far away you are from exceeding the TBM limit.Your TBM of 250 is within the limit of 300 by 50
Margin to GCM:	900	You are within the GCM limit of 6000 by 900.
Margin to GVM:	250	You are within the GVM of 3100 by 250.
Margin to max tow:	500	Your trailer weight of 2500 is within the max tow of 3000 by 500.
Payload left before reaching a weight limit:	250	In this configuration, your payload is limited by GVM.
The heaviest trailer this towcar can tow is:	3000	This is the heaviest trailer you can tow given the weights input above (assumes 10% TBM). Your maximum trailer weight is the towcar's maximum braked tow limit.
1. The changes to front and rear axle loads are approximate as they depend on precise TBM measurements. Tandem axle trailers typically exert less force on the rear axle for a given TBM than single axles as the tandems have some counterbalance effect. This calculator gives approximate guidance. Have your vehicle professionally weighed for accurate and precise measurements. Version 11 - 19/01/2022

If you have questions, comments or feedback please post them on the help page, after you’ve read it and the explanations 🙂

You may also like to try the Tyre Size Calculator.

The calculator and the information provided is free to you but cost me to produce and maintain, so please consider supporting me on Patreon and YouTube. Sponsorship welcome so long as independence is maintained.