Ensuring the right fit for your horse's bit is crucial for your horse’s comfort and the proper function of the bit you are using. When looking for a new horse bit, whether buying a bit for the first time or experimenting with a new style, learning how to measure your horse for a bit properly is equally important as the type of bit you choose.

A common mistake riders make is using a bit that is too small or too large. Contrary to popular belief that a larger bit is kinder due to having extra room, it can lead to discomfort and hinder communication. To achieve an ideal fit, the bit should be at the correct height, snugly fitting into the corners of the mouth and parallel to the roof's second two grooves. In this guide, we will teach you how to know if a bit is too small or large for a horse, how to choose a bit, and the best method for finding your horse’s bit size.

Understanding Horse Bits

A horse bit is an integral part of riding tack in nearly every discipline and style of riding. The bit is connected to the bridle and positioned inside the horse's mouth, specifically in the toothless area at the back, where it rests on the tongue. It is crucial for the bit to sit comfortably in the horse's mouth as it plays a key role in reinforcing riding or driving cues by applying pressure to the tongue and hard palate, aiding in controlling speed and direction. While steel remains the most commonly used metal for horse bits, copper, rubber, and other materials have been introduced into some styles depending on the purpose of the bit.

The most common styles of horse bits are:

  • Snaffle bits
  • Tom Thumb bits
  • Curb bits
  • Correction and Port bits
  • Pelham Bits
  • Kimberwick Bits
  • Twisted wire bits
  • Roller bits
  • Spade bits
  • Spoon bits
  • Gag bits

Knowing the 101 of Horse Bits from understanding the different types of bits and their uses will help you know how to choose a bit for your horse and make an educated decision when bit shopping. Choosing the right bit will ensure a long and happy partnership between you and your horse while achieving the goal you are looking for, whether it is adding more control and leverage for a strong or heavy horse, aiding in a better connection, allowing a young horse to accept a bit, or for more advanced training. Want to learn more about snaffle bits? Check out Horse Bits 101: What is a Snaffle Bit?.

Measuring for a Horse Bit

You can choose from a few methods to measure your horse for a bit. A Bit Sizer is a small plastic tool with measurements already measured on the device that allows you to instantly identify the size bit your horse needs. If you do not have access to a Bit Sizer, you can use various items around your barn or home that can work, such as a ruler, marker, and either a piece of soft rope or twine from a hay bale.

Steps on How to Measure Your Horse's Bit Using the String Method:

  1. First, cut your piece of string or rope to be roughly the length of your forearm. This allows you plenty at either end to hold onto while keeping your horse from accidentally eating the string.
  2. Near the center, clearly mark a line on the string with a marker.
  3. Insert the string into your horse’s mouth where a bit would go, with your marked spot just outside their lips on one side. Use your other hand to move your fingers to where the opposite side sits at their outside lip.
  4. Remove the string while ensuring your fingers don’t lose their spot on the side without marking a line.
  5. Use the marker to mark that spot on the string.
  6. You can now lay the string flat and use a ruler to measure the distance between your marked lines.
  7. The type of bit you are using may alter your measurement slightly. If you will be using a bit with a curved mouthpiece or very thick mouthpiece you will want to add 1/4 to 1/2-inch to your measurement to account for the extra space the bit will take up.

Choosing the Right Bit Size

Bit Size Graphoc - Choosing the Right Bit Size

Now that you know how wide the bit should be for your horse, you must determine a suitable mouthpiece and cheekpiece style and size. The mouthpiece length on a horse bit is what the size of the bit refers to when you shop for a bit. If you see a bit advertised as a “5-inch Snaffle”, for example, that means the mouthpiece measures 5” wide from inside the cheek pieces. The mouthpiece circumference or thickness will vary. Typically, a wider mouthpiece will be a “softer” as the pressure has more surface area to distribute across.

Some horses will have a low palate where the space between their tongue and the roof of their mouth might not be as roomy as other horses. You can get a good idea of the space in your horse's mouth by lifting the side of their lips up. If you see quite a bit of room between the top of their tongue and the roof of their mouth, they likely have an average-sized palate. However, if the space is slim or their tongue pushes out to the side of their lips a bit, they might have a low palate or a large tongue, which will result in needing a thinner bit. Your veterinarian or equine dentist can advise you on what type of space your horse has if you are unsure. Horses with low palates tend to do better with thinner or average-sized mouthpiece thicknesses. A thick, bulky rubber snaffle, for example, will likely be uncomfortable for them.

What is the cheek measurement on a bit?

Every bit is designed with a purpose, from the mouthpiece to the cheek style. The cheekpiece or ring diameter of a bit plays a role in the action or purpose of a bit. Cheek measurements typically come in either inches or millimeters, measuring the diameter of how large the cheekpiece is. A typical loose ring snaffle will be an average size, designed to be a mild bit if compared to something like a shank cheek piece which will give you more leverage and control. A bit with a very large cheekpiece style will give you more control on the side of your horse’s mouth, often helpful with turning or steering, whereas a smaller cheekpiece size may be suitable for a well-trained horse that respects the aids. The size of a cheek measurement on a bit is also relative to the size of your horse’s head. A refined horse may need a smaller cheekpiece size to ensure it doesn’t rub their cheekbones.

What is the average bit size for a horse?

The average bit size for a horse is 5 inches wide. Most ponies or refined breeds wear a 4.5-inch bit, horses 5 inches, and large warmblood or smaller draft horses will wear a 5.5-inch bit. Some bits come in a size of 6 inches and are often only used for very large heavy-breed draft horses. It is important to remember that every horse is different and that each individual bit can require a slightly different size for your horse. The amount of curve a bit has, the circumference of the mouthpiece, and the size of your horse’s palate will all play a role in the best size to suit your horse.

How do you know if a bit is too small for a horse?

Having a bit that is too large or too small can cause problems for your horse. How do you know if a bit is too small for a horse? There are a few simple tricks to check that your bit fits just right. The bit should rest at the corners of your horse’s mouth without pressing into the side of your lips or face. If the bit is pressing into their face or lips, your bit is too small, and the mouthpiece is too short, which can cause rubs and sores. On the contrary, if the bit is sticking out of their mouth so far that you can see more than 1/2” of the mouthpiece showing on both sides, it is too large and can be just as uncomfortable, sliding through their mouth and causing sores inside their lips. A good rule of thumb is that you want enough space between the bit and your horse’s lips so that the bit won’t pinch or rub, and you want to see two visible wrinkles in their lips just behind the mouthpiece.

If you are using a loose ring snaffle-type bit, even properly fitted, it is common to add rubber bit guards, which are thin rubber guards to prevent the ring from pinching your horse’s lips as the ring spins freely through the mouthpiece.

How to Care for Your Horse Bit

Caring for Your Bit

Caring for your horse's bits not only keeps them looking great, but a clean bit will be more comfortable for your horse and prevent the action of the bit joints from working their best. Knowing How to Clean Horse Tack properly will prolong the life of your tack and horse bits. Wiping down your horse bit with water and a rag after every use is an easy way to keep the daily grime from building up. Ultra Horse Bit Cleaner and Freshener is perfect for cleaning and disinfecting bits, especially beneficial for busy barns where bits may be shared with other horses to help prevent the spread of illnesses and viruses. This type of bit cleaner has a yummy peppermint flavor, and you can even use it to buff a brilliant shine into your bits so they are always looking ready for the show ring!

You should always replace any bits when they show damage or wear. For example. rubber bits or Happy Mouth bits tend to get chew marks, especially from young or anxious horses that chomp on the bit. Over time these marks can become quite sharp, as a disadvantage to having a softer bit. Those sharp edges can be painful and even scrape your horse’s mouth or tongue.

Now that you know how to measure for a horse bit and choose the right sized bit for your horse, you can start bit shopping and add to that always-growing bit collection, ensuring you always have the right size for your horse or pony. As they say, you can never have too many bits!