Horsebox payload explained

Horsebox weights can get confusing very quickly.

You will see terms such as payload, MAM, gross weight, train weight, towing capacity and noseweight, often used as though they mean the same thing.

They do not.

The most important thing to remember is:

A 3.5-tonne horsebox cannot carry 3.5 tonnes.

The 3.5 tonnes normally refers to the maximum permitted weight of the entire vehicle once loaded, including the horse, driver, passengers, fuel, tack, water and everything else on board.

The same principle applies to trailers. Just because a trailer has space for two horses does not automatically mean you can legally carry any two horses in it.

The main horsebox weight terms

You may also see tongue weight online. This is mainly American terminology for what we normally call noseweight in the UK.

What is payload?

Payload is the amount of weight available for everything you add to the vehicle.

For a motorised horsebox, a basic calculation is:

MAM - empty vehicle weight = payload

If you already know your horsebox's MAM and current weight, our Horsebox Payload Calculator can work out the remaining payload for you.

So if a horsebox has:

• MAM: 3,500kg
• empty weight: 2,700kg

the theoretical payload is:

3,500kg - 2,700kg = 800kg

That sounds like plenty until you start loading it.

The payload may need to cover:

• horse
• driver
• passengers
• tack
• saddles
• rugs
• water
• feed and forage
• grooming equipment
• first aid equipment
• tools
• personal belongings
• anything else carried in the vehicle

This is why the advertised payload figure should not be treated as the weight of horse you can carry.

A realistic 3.5-tonne horsebox example

Suppose your horsebox has a MAM of 3,500kg.

You take it to a weighbridge with the fuel you normally carry, the driver, your normal tack, water and equipment already on board.

It weighs:

2,850kg

That leaves:

3,500kg - 2,850kg = 650kg

Your horse weighs approximately 600kg.

Once loaded:

2,850kg + 600kg = 3,450kg

You now have only:

50kg remaining

A passenger, extra water, feed or additional equipment could easily put the vehicle over its permitted weight.

This is why knowing the real weight of your horse matters.

If you do not know it, use our Horse Weight Estimator to get a useful estimate.

Do not rely on the advertised payload

A manufacturer's or dealer's payload figure can be useful when comparing horseboxes, but it is not a substitute for weighing the finished vehicle.

Horseboxes can gain significant weight through:

• living areas
• additional seats
• reinforced partitions
• storage
• ramps
• leisure batteries
• water tanks
• tow bars
• air conditioning
• extra bodywork
• fitted accessories

Second-hand horseboxes may also have been altered since they were originally built.

The most useful figure is the weight of your actual horsebox in the condition you normally use it.

The safest way to check payload

Use a public weighbridge.

For a motorised horsebox, take it in roughly its normal travelling condition, but without the horse.

Ideally include things that will normally be present, such as:

• fuel
• driver
• normal water supply
• tack
• equipment
• spare wheel
• usual supplies

Subtract the weighbridge result from the plated MAM.

For example:

3,500kg MAM - 2,920kg actual weight = 580kg remaining capacity

You then know what is actually left for the horse and anything else you add.

GOV.UK has a public weighbridge finder.

What about axle weights?

Staying below the total MAM is not enough.

Vehicles also have maximum permitted axle weights.

A horsebox could weigh only 3,450kg overall and still be overloaded if too much of that weight is sitting over the rear axle.

This is particularly relevant to horseboxes because the horse compartment is often behind the cab and much of the horse's weight may be carried by the rear axle.

The vehicle plate may show figures for:

• maximum front axle weight
• maximum rear axle weight
• overall MAM
• gross train weight, if the vehicle is approved for towing

Each applicable limit must be respected.

Where possible, ask the weighbridge whether individual axle weights can also be checked.

Horse trailer payload

Trailers have their own maximum permitted weight.

For example, imagine a horse trailer with:

• MAM: 2,700kg
• empty weight: 1,000kg

The apparent payload is:

2,700kg - 1,000kg = 1,700kg

You then load:

• horse one: 600kg
• horse two: 550kg
• tack, water and equipment: 100kg

The added load is:

1,250kg

That sounds comfortably within the trailer's available capacity.

But that is only one of the limits you need to check.

You also need to consider:

• the towing vehicle's maximum towing capacity
• gross train weight
• towing vehicle MAM
• towing vehicle axle limits
• trailer axle limits
• noseweight
• towbar and coupling limits
• your driving licence entitlement

A trailer can be within its own weight limit but still be too heavy for the vehicle towing it.

What is noseweight?

Noseweight is the downward force that a trailer places on the towing vehicle through the towball.

You may also see it called:

• tongue weight
• tongue load
• vertical coupling load
• towball load

In the UK, noseweight is the term you will see most often.

The trailer should place an appropriate downward load on the towball when correctly loaded.

Too little noseweight can reduce towing stability and increase the risk of the trailer swaying or snaking.

Too much noseweight can overload the towbar, suspension or rear axle of the towing vehicle and can reduce the load on the vehicle's front axle.

Is noseweight part of payload?

Treat noseweight as another weight limit that needs checking, not as extra carrying capacity.

When a trailer is coupled to the towing vehicle, some of its weight is transferred through the towball.

That load affects the towing vehicle, particularly its:

• gross vehicle weight
• rear axle loading
• suspension
• towbar

So even if the trailer itself appears comfortably within its weight limit, excessive noseweight can still overload the towing vehicle.

What should the noseweight be?

There is no single noseweight figure that applies to every horse trailer.

You will often see 5% to 7% of actual laden trailer weight quoted as general towing guidance, particularly for caravans.

Do not treat that as a universal horse trailer rule.

The correct figure depends on the:

• towing vehicle
• towbar
• trailer
• coupling
• way the trailer is loaded

The manufacturer's specified limits take priority.

Check the towing vehicle handbook and the ratings fitted to the towbar and trailer.

Where several maximum figures apply, you need to stay within the lowest applicable limit.

For example, if:

• towing vehicle maximum noseweight: 100kg
• towbar maximum vertical load: 120kg

then the 100kg vehicle limit is the one that restricts you.

The trailer or coupling may impose another limit as well.

Why loading position matters

Noseweight is heavily affected by where the load sits, not just how much it weighs.

Imagine the trailer as a seesaw around its axles.

Moving weight towards the front generally increases noseweight.

Moving weight towards the rear generally reduces it.

This means putting several containers of water, feed bags and tack into a front locker can materially change the noseweight without changing the total amount of weight being carried.

The British Horse Society specifically warns that carrying spare water, feed and forage at the front of a horse trailer can cause the noseweight to be exceeded.

With a horse trailer, follow the manufacturer's instructions for:

• horse position
• partitions
• breast and breeching bars
• travelling one or more horses
• storage and equipment

A horse is also a live load that can move during the journey, which is another reason not to treat a horse trailer like an ordinary box trailer full of fixed cargo.

How do you measure noseweight?

Noseweight can be checked using a suitable noseweight gauge and the procedure specified by the vehicle or trailer manufacturer.

The trailer should be loaded in its normal travelling configuration and the measurement should be taken correctly at the coupling.

Do not attempt to uncouple or jack up a horse trailer with horses inside simply to measure noseweight.

If you are unsure about your particular trailer, ask the trailer manufacturer, dealer or a competent towing specialist to confirm the correct procedure and limits.

What is gross train weight?

Gross Train Weight, usually shortened to GTW, is the maximum permitted combined weight of:

towing vehicle + trailer + everything carried

For a car or 4x4 towing a horse trailer, you therefore have several different limits at the same time.

For example:

The trailer having a 2,700kg MAM does not mean this particular vehicle can tow it at 2,700kg.

If the vehicle manufacturer only permits a 2,500kg trailer, that lower limit still applies.

Likewise, the combined actual weight must stay within the vehicle's gross train weight.

GOV.UK advises checking the towing vehicle handbook, specification and VIN plate for these figures.

If the VIN plate does not specify a train weight, GOV.UK states that the vehicle should not be used for towing.

MAM is not the same as actual weight

This distinction causes a lot of confusion.

MAM is the maximum the vehicle is allowed to weigh.

Actual weight is what it weighs right now.

A 3,500kg MAM horsebox might currently weigh 2,900kg.

A 2,700kg MAM horse trailer might currently weigh 2,100kg.

The plated number is the ceiling, not a statement of what the vehicle always weighs.

Do not forget the horse

Horse weights vary enormously.

A small pony might weigh a few hundred kilograms while a large horse can comfortably exceed 600kg.

Two apparently similar horses can also differ significantly in weight.

If payload is tight, estimating both horses as "about 500kg" is not good enough.

Use:

• a weighbridge where available
• an equine weigh tape
• body measurements and a weight formula

Our Horse Weight Estimator can give you a useful starting figure.

Leave some margin

If your calculation comes out at exactly the legal maximum, you have no allowance for error.

There can be uncertainty in:

• horse weight estimates
• water carried
• fuel quantity
• equipment
• passengers
• weigh tape estimates
• changes made to the vehicle

For example, if a 3.5-tonne horsebox calculates to exactly 3,500kg once the horse is loaded, that is not a particularly comfortable position to be in.

Where possible, leave a sensible margin rather than planning to operate permanently at the exact limit.

What driving licence do you need?

The licence rules depend on whether you are driving a motorised horsebox or towing a trailer.

In Great Britain, a normal Category B car licence allows vehicles up to 3,500kg MAM.

For a motorised horsebox above 3,500kg, you will normally need the appropriate C1 or C entitlement depending on its MAM.

For car and trailer combinations, the rules changed in Great Britain in 2021. Drivers with a GB car licence can generally tow trailers up to 3,500kg MAM under Category BE, but the vehicle and trailer still have to remain within their own legal and manufacturer weight limits.

Northern Ireland has different towing licence rules, particularly for drivers who passed their car test from 1 January 1997. Check NI Direct rather than assuming the Great Britain rules apply.

Your driving licence entitlement does not increase what the vehicle itself is capable of towing.

Commercial horse transport

If you are transporting horses in connection with a business or other economic activity, additional rules can apply.

Depending on the vehicle, journey and circumstances, these can include:

• operator licensing
• drivers' hours
• tachograph requirements
• animal transporter authorisation
• certificates of competence
• vehicle approval requirements

Private leisure transport and commercial transport are not always treated in the same way.

Check the current GOV.UK guidance if the journey is connected with a business, paid transport or another economic activity.

Before travelling

Before setting off, make sure you know:

• your horsebox or trailer's MAM
• its actual weight
• remaining payload
• horse weight
• axle limits
• towing vehicle MAM
• towing capacity
• gross train weight
• noseweight limits
• towbar and coupling limits
• your driving licence entitlement

Do not assume that because the horse physically fits, the vehicle can legally carry it.

The simple answer

Payload is how much usable weight your horsebox has left once the vehicle itself is taken away from its maximum permitted weight.

For a motorised horsebox:

MAM - actual vehicle weight = remaining capacity

For trailers, you also need to check the trailer's own limit, the towing vehicle's towing capacity, gross train weight, axle weights and noseweight.

And if you only remember one thing:

"3.5 tonne horsebox" means the complete loaded vehicle can weigh up to 3.5 tonnes. It does not mean it has a 3.5-tonne payload.