What this checker works out
This checker gives the caravan-to-car weight ratio and flags whether the caravan exceeds the towing limit you enter.
The ratio is a guidance figure, not a legal one. Several separate limits apply to towing, and the checker tests only one of them — the others are listed below and all of them bind independently.
Enter your details
The limits that all apply at once
- The car's maximum towing mass, from the handbook or the VIN plate. This is a manufacturer limit and exceeding it is unlawful.
- The gross train weight — the maximum for car and trailer combined, loaded. A car at its own maximum has less towing capacity left.
- The towbar's own rating, which may be lower than the car's.
- Your driving licence category. What you may tow depends on when you passed your test.
The widely quoted figure — that a caravan should not exceed 85% of the car's kerb weight — comes from towing organisations as a stability recommendation for less experienced drivers. It has no legal force. What is legally binding is the manufacturer's towing limit, the gross train weight, the towbar rating and the licence category, and a combination can satisfy the 85% guideline while breaching all four.
How this calculator works
A ratio and a single limit test:
Ratio = caravan MTPLM ÷ car kerb weight × 100
Flagged if caravan MTPLM exceeds the stated tow limit
MTPLM is the maximum technically permissible laden massMTPLM is the caravan's maximum permitted loaded weight, not its empty weight. Using the unladen figure understates the ratio substantially and is the most common error here.
Kerb weight is the car with fluids and a full tank but no passengers or luggage. Some published ratios use different definitions, so comparing figures from different sources requires checking which is meant.
Worked example: a 1,300 kg caravan
Using the default figures — a 1,600 kg car, a 1,300 kg caravan MTPLM, a 1,500 kg tow limit:
- Weight ratio: 81%
- The caravan is within the stated tow limit
81% sits just inside the 85% guideline, which is reassuring and does not settle the question. The same combination could still exceed the gross train weight once the car is loaded with four people and luggage, or exceed a towbar rated below the car's limit, or fall outside the licence category of a driver who passed after January 1997. Each needs checking separately.
Common mistakes
- Using the caravan's unladen weight. MTPLM is the figure that matters.
- Treating 85% as the legal test. It is a stability guideline with no legal force.
- Forgetting the gross train weight. A fully loaded car reduces what it can tow.
- Assuming the towbar matches the car. It has its own rating and may be lower.
- Not checking the licence category. Rules differ depending on when you passed your test.
Frequently asked questions
What can I tow on my licence?
It depends on when you passed. Drivers who passed a car test before 1 January 1997 generally have wider entitlement. Those who passed after that date have category B, and the rules on trailer towing for that category were changed in late 2021 to remove the previous separate B+E test requirement. Because the position has changed, checking your own entitlement on the government's licence checker is the only reliable answer.
What speed limits apply when towing?
Lower than for a solo car: generally 50 mph on single carriageways and 60 mph on dual carriageways and motorways, where the national limits would otherwise be 60 and 70. Towing vehicles are also prohibited from the outside lane of a motorway with three or more lanes.
How do I stop a caravan snaking?
Load heavy items low and over the axle, keep the noseweight within range, maintain correct tyre pressures on both vehicles, and reduce speed. If snaking begins, ease off the accelerator gently and hold the steering straight — braking hard or steering to correct usually makes it worse. Stabilisers reduce the tendency but do not remove the causes.
Does the caravan need its own test or checks?
Caravans are not subject to MOT testing in the UK, which places the responsibility on the owner. Tyres age out rather than wear out on a caravan used seasonally, and are commonly recommended for replacement after five to seven years regardless of tread. Brakes, bearings and the coupling should be serviced annually.
Is what I enter stored?
No. Weights are processed in your browser and never transmitted or retained.
Related tools
References
- GOV.UK — towing rules, licence categories, weight limits and speed limits
- Health and Safety Executive — safe loading and vehicle weight guidance
Sources are checked at publication and can change — how I choose and check references.