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Acceptable Weight / Horse Ratio

Master Saddler & Master Saddle Fitter Kay Hastilow has been working to develop a new formula that seeks to enable a more accurate assessment of the weight that an individual horse or pony can comfortably carry and the results of that study have just been published. Kay explains more about what the new formula is and the potential welfare benefits it offers ...

Acceptable weight / horse ratio (c) Expo Life 2022From my blog post ‘The Elephant In The Room’ I have seen many comments asking what ratio is acceptable for rider weight to horse size. If only it were that simple! Many use the 10, 15 or 20% guidance but these really aren’t of much use. Let’s say that I am 70kg, at least 85kg and probably more if you include my clothing, hat, boots and the like plus saddle, bridle, girth, breastplates, stirrups and so on. 1m 70 tall and ride a 15-2hh thoroughbred ex-racer. The horse is 500kg (for ease of figures.) At 10% the maximum weight that he could carry including all of the extra baggage would be 50kg. Hmm. Not very likely is it, that any adult could weigh 50kg with tack and clothing included.

Let’s try 15%. 75kg. which is slightly more realistic but still well below the 85 kg that is actually the weight he has to carry.

20%? That makes 100kg total weight, 85kg for the rider alone, which really sounds too much. Unfortunately all of these formulas miss out on many important factors. Apart from the weight, how fit and athletic is the rider? An unfit person may well have poor core strength, sit ‘heavily’ in the saddle, not have just such good balance or stability as the fit rider. Yes, I know that some larger riders ARE fit and Do Have Good core strength but I think that they will admit that they are the exception rather than the rule.

You will notice that the formula says, ‘so many percent of the horse’s bodyweight.’ But there is no consideration to the type, age or condition of the horse. A just backed 4 year old, would really not want to be carrying 20% or even 15% of their bodyweight until they were stronger and more balanced themselves, An older horse may well struggle with a heavier rider. Likewise breed types. TBs are very deep in the chest as a general rule as they need large hearts, and so more heart room to be successful racing. However the bone and general build of the horse does not really carry heavier weight well whereas a stouter horse, a good cob say, can carry that weight, although if you are using a weight tape for gauging the horse’s weight they may well come in as the same weight. Nowhere is the breadth of the quarters, nor the bone beneath the knee taken into consideration, nor the fitness of the horse, although including these gives a much better idea of the horse’s ability to carry certain weights. My granddaughter and I have played about with this in the past using horses in a riding school, along with the very knowledgeable and experienced owner who gave us her opinion as to what rider weight each horse could carry, and we came up with a formula that, whilst it isn’t straightforward, is the most accurate that I have seen. It doesn’t take age or fitness into consideration but I think the rest is there.

This is the formula (measured in centimetres):-

Measure point of hip over the quarters to point of hip. (q)
The circumference of bone beneath the knee. (b)
Circumference of trunk at girth point, where you would use a weight tape. (g)
Height of horse to top of wither. (h)
((q+b) x h)x g) /39095 = maximum weight that can be carried.

This will give you the weight that the horse can carry in Kilograms including tack and clothing.

Yep, it sounds crazy but it does seem to work, however it’s nowhere near as easy as just saying ‘15%’ is it?
This formula arrived at a rider weight to horse ratio that seemed acceptable for the riding school horses that we saw in our trial – a fair mix of cobs, weight carrying horses, finer riding horses and a couple of thoroughbreds so a good range and should be a good guide for most if you allow for age and fitness level, reducing the acceptable weight in relation to these but never increasing it.

Have a play with this, and see what everyone thinks? Any carefully thought out and tested formulas that anyone has would be a huge help with this rider weight question but it is because it is so complex a question that there is no official advice out there.

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