It’s About More than Width
Saddle fitting can be a scary venture.
A friend once said, “Saddle shopping is like going to the store to buy a two-piece bikini for someone that you haven’t seen in a few years.” I would absolutely agree with this. Continuing with that comparison, we don’t just measure women by their width when shopping for a bikini. Every woman has a different shape, beautiful curves, varying heights, and likely needs a different size for the top and bottom. It’s unlikely that you can go to the store, pick out a “medium,” and hope it works for that friend.
Horses are similar, they don’t conform to the sizes that their breed suggests. There are several parts of their body that we need to fit to the saddle they’re being ridden in. We have to take into account the following shapes and angles to find the right saddle for them:
The width of the horse behind their scapula
The angle of their back from spine to sides (medial to lateral)
The curve of their spine from front to back (cranial to caudal)
How long of a saddle their thoracic spine can handle
So, if we need to take all of these into account, why are we only shopping for saddles based on width? We see it all the time: “I’m shopping for a dressage saddle with a wide tree.” This is the same as your friend asking you to run to the store to grab them a medium swimsuit. Do they want a one-piece? A two-piece? Strapless? Tie on the sides? Patterned? Floral? Sporty? Is my Florida background coming out in this blog post?
The width of the horse behind their scapula
To measure your horse for the correct tree width, a handy tool to use is a flexicurve. This bendy ruler can help you determine the width your horse needs. However, it must be placed and measured correctly. Rather than write out how to do this, I’ve included a video from a saddle fitter named Poppy Webber. It offers a great explanation of what to use and why.
If the angle of the front of the saddle (the tree points) is off, it can cause pressure points on the horse. When I first started looking into saddle fitting for my own horse, I didn’t understand how this worked. I kept thinking, “I need to go wider,” because I kept feeling tightness under her saddle.
Tightness under your saddle is an indicator that the saddle isn’t fitting correctly, but where it’s tight is the important part.
Think about this concept by imagining your horse as a triangle. If you place a saddle that is too wide, you’ll feel tightness at the top of the triangle. The saddle will sit low and won’t have enough clearance over the withers. If the saddle is too narrow, it will make contact at the bottom of the triangle, sit too high, pinch at the bottom of the tree points, and give you too much clearance.
Often, clearance is measured by the number of fingers you can fit between the saddle and the withers. You may have heard, “Four fingers is ideal.” While this is a good rule of thumb, it’s not always accurate. The saddle changes when it is girthed up and sat in, and other factors can also affect this. Just because a saddle has four fingers of clearance doesn't mean it's the right fit, and the opposite is also true. Sometimes a saddle with three fingers of clearance fits quite well.
A correctly sized tree width won’t have pressure points and will sit parallel to the horse.
The angle of their back (medial to lateral)
This measurement can be tricky and isn’t always quantified like tree width. It also changes with the seasons and your horse’s topline. This angle is extremely important in determining how angular a saddle’s panels need to be.
For comparison:
A horse with a flat, broad back will need flatter panels.
A horse with a more peaked spine will need more angular panels.
The bottom of the panels needs to make full, even contact along the entire back.
Saddles built for broader horses tend to have flatter, sometimes thinner panels. If you place a saddle with angled panels on a broad back, they’ll only make contact at the outer edges, causing instability and pressure points.
A horse with an angular back, either naturally or due to a weak topline, needs panels with more angle. When such a horse is ridden in a saddle with flat panels, they often experience pressure around their dorsal spinous processes and supraspinous ligament. I’ll discuss topline improvement in another post, but this provides a good basis for understanding the connection between panel shape and tree angle.
Note: Small changes can be made using shims or flocking to adjust a panel, but this must be done by a professional.
The curve of the spine (cranial to caudal)
This curvature is where we run into terms like bridging. The curve of the tree is essential for proper weight distribution.
If the tree is too flat, it will bridge, meaning it only touches the front and back, leaving a gap in the middle.
If the tree is too curvy, the saddle will take on a "banana" shape and sit high in the front, lacking contact in the back.
This can be deceptive, as the saddle might look too narrow because it’s sitting high in front, but the actual issue is with the shape, not the width.
To check:
Place the saddle on your horse without any pads.
Run your hand under it.
Do you feel pressure in the front and back but a gap in the middle?
Is your hand getting stuck in the middle but moving freely in the back?
This is a tough concept to teach in a blog because so much depends on feel and movement. Horses lift and change shape when properly ridden. But it’s still crucial to be aware of this factor.
In Western saddles, this concept is referred to as "rock." Think of a rocking chair to help remember the idea.
How long of a saddle their thoracic spine can handle
Horses can only comfortably handle a saddle of a certain length. You may have seen photos from saddle fitters (myself included) showing horses with chalk lines on their back. These lines mark the areas where the saddle can be safely placed.
The furthest-back line usually marks the last thoracic vertebra (T18). You find this by locating the last rib and following its angle upward. After T18, the vertebrae change shape, and the muscle structure becomes less supportive. The lumbar spine is not built to carry a saddle.
This is critical for comfort and safety. While we don’t want to cram a rider into too-small of a saddle, we must respect the horse’s back length.
Some saddles are designed with swept-up panels for short-backed horses, and others have seats that extend slightly over the panels to accommodate longer-legged riders. These design choices matter.
In Conclusion
If this all sounds a little overwhelming, that’s okay. That’s why saddle fitters exist. My husband once said, “If we could have paid someone to find a saddle for you when you were looking, it would’ve saved us more money and time than the cost of the assessment.”
That’s not even counting the actual money lost on saddles that didn’t work.
Saddle fitting is complex—and the topics I’ve covered here barely scratch the surface. The purpose of this post is to show that saddle fitting is about so much more than width.