Stirrup length is different for every student and stirrup length preferences can differ for instructors as well. Personally, when I ride I prefer my stirrups to be slightly on the short side. Stirrups can be too short and they can be too long, so how does one figure out what is right for them?
A good guide to estimate stirrup length from the ground is what I call the arm-pit test. A rider takes the stirrup length and makes it long so when they have their fingers on the buckle of the stirrup leather the bottom of the stirrup iron hits them in the arm-pit when they stretch it out with their arm. The stirrup leathers should always be the length of a riders arm. Once mounted, it is best for a rider to double check their stirrup length. "With your feet out of your stirrups, the stirrup irons should hang at your ankle bones." (1)
For children an instructor needs to be able to find the right stirrup length for them. "A child has not the strength to ride [with their stirrups] long, but an over-short stirrup makes it difficult for the child to use his or her legs effectively. A good guide is that the child should ride at jumping length; riding longer makes balance more difficult to master." (2)
Why one person chooses a particular stirrup length is generally a practical decision based on rider preference. To start this research I went to Sally Swift's book Centered Riding. In it she states that "It [the length of your stirrups] varies according to the conformation of the rider and the horse, and also with the type of saddle used." (3) She goes on further to say:
"If you find you must reach for your stirrups, they are too long; your feet will swing forward and you will lose your bottom building block. If you are long legged and/or your horse is round and shallow-bodied, you will need to shorten the stirrups in order to reach his sides with your legs. Your stirrup leathers will probably be at least two or three holes longer for flat work than for galloping or jumping, but must hang straight, behind your knee and in front of your ankle, with your hip joint over your ankle." (3)
Again, as stated above, the length of your stirrup depends on the kind of work you are planning to do with your horse and/or your student. In the book "Complete Horse Riding Manual" by William Micklem, Mr. Micklem suggests that there are three general lengths when discussing stirrups:
"Dressage Length: The angle at the back of your knees should be around 120-130 degrees, with your knees and toes pointing forward. If you ride longer than this, it is not possible to keep the lower leg in contact. If your horse is very wide, you will have to ride a little shorter.
Jumping Length: The angle at the back of your knees should be around 105-115 degrees. This shorter position makes it easier to keep the balance through the led in order to go with the horse's jump. If you are short and the horse is big, it may help to ride a little longer.
Cross Country Length: The angle at the back of your knees should be around 90-100 degrees. The disadvantage to riding shorter is that there is more weight in the leg, so it is more difficult to use the leg aids. The shorter you ride, the lower you should keep your heel." (4)
What is a perfect stirrup length? It is the length - depending on the size and confirmation of the horse and rider - that is correct for the work that you and your horse and/or student will be doing. My suggestion, start with the arm-pit test, double check stirrup length once mounted to see if the stirrup iron rests at your ankle bone, and adjust accordingly from there.
(1) Richter, Judy. Judy Richter's Riding for Kids: Stable Care, Equipment, Tack, Clothing, Longeing, Lessons, Jumping, Showing. Storey Publishing,
(2) Wallace, Jane. Teaching Children to Ride: A Handbook for Instructors. Kenilworth
(3) Swift, Sally. Centered Riding.
(4) Micklem, William. Complete Horse Riding Manual. Dorling Kindersley Ltd,
