Quick answer (updated October 2026)
The 20% rule is a long-standing rule of thumb that a horse should carry no more than 20% of its own bodyweight, including the rider and the saddle and tack. So a 500kg horse should carry no more than about 100kg in total. Many experts now suggest aiming lower, around 15%, for horses doing harder or longer work. It is a guideline rather than a strict limit, because the horse’s fitness, build and the rider’s balance all make a big difference.
What is the 20% rule in horse riding?
The 20% rule is a simple guideline used by riders, riding schools and trekking centres to help make sure a horse is not overloaded. It says that the combined weight of the rider and all the tack, including the saddle, numnah and bridle, should be no more than 20% of the horse’s bodyweight.
Nobody knows exactly where the rule came from. It grew out of the experience of horsemen over many years, and it is still the most widely quoted guide today.
How to work out the 20% rule
To use the rule, you need three numbers:
- Your horse’s weight. A weighbridge is the most accurate, but a weigh tape gives a reasonable estimate.
- Your weight, in your riding clothes, boots and hat.
- The weight of your tack. A saddle can weigh anything from around 5kg to more than 15kg.
Multiply your horse’s weight by 0.2 to find the maximum it should carry, then compare that with your weight plus the tack.
| Horse weight | 20% (maximum total) | 15% (lighter target) |
|---|---|---|
| 300kg (small pony) | 60kg | 45kg |
| 400kg (large pony or cob) | 80kg | 60kg |
| 500kg (average horse) | 100kg | 75kg |
| 600kg (large horse) | 120kg | 90kg |
| 700kg (heavy horse) | 140kg | 105kg |
Remember these totals include the tack, so the rider’s own weight needs to be several kilograms lower.
Is 20% too much?
Research in the UK has looked at how rider weight affects horses, and some horses carrying riders towards the heavier end of the range showed short-term signs of discomfort. Because of this, many vets and instructors suggest that 15% is a kinder target, especially for long hacks, fast work, jumping or hilly ground. The 20% figure is best seen as an upper limit rather than a goal.
Other things that matter as much as weight
- The horse’s build. Horses with short, strong backs, good bone and wide loins, such as cobs and many native breeds, usually carry weight more easily than finer types.
- Fitness and age. A fit horse copes better than an unfit one, and very young or older horses may need lighter loads.
- Rider balance and skill. A balanced, secure rider is much easier to carry than an unbalanced rider of the same weight.
- Saddle fit. A well-fitted saddle spreads the weight evenly. A poor fit can cause pain whatever the rider weighs.
- The work. A short walk in the arena is very different from a long day’s hack or a jumping lesson.
Weight limits at riding schools
Most riding schools and trekking centres set a maximum rider weight, often based on the 20% rule and the horses they have available. This is about protecting the horses, not judging riders, and many centres have larger horses or cobs for heavier riders. If you are unsure, call the riding school before you book and ask what their limit is.
Free tool: Not sure what your horse weighs? Use our free horse weight calculator to estimate it from a few measurements, or try the rider weight calculator to see what size of horse suits you.
Frequently asked questions
Does the 20% rule include the saddle?
Yes. The 20% should include the rider, their clothing and all of the tack, including the saddle.
How much weight can a 500kg horse carry?
Using the 20% rule, a 500kg horse should carry no more than 100kg in total, including tack. Using the lighter 15% guide, the total would be around 75kg.
What breed of horse is best for a heavier rider?
Stocky, strong types such as cobs, Irish Draughts, Highland and Fell ponies, and some draught crosses are often good choices for heavier riders, as long as they are fit and the saddle fits well.
Find a riding school near you
Looking for lessons or a trek suited to you? Search our directory of UK riding schools and equestrian centres, then contact them to ask about their horses and rider weight limits.
