Choosing and Fitting a Bit
The bit is a small piece of tack that has a large effect on comfort and communication. This guide explains how to size a bit, what the main types do and how to check that it fits.
Measure the mouth
Bit size is the width of the mouthpiece between the cheek pieces or rings, in inches. Most horses take a bit between 5 and 5.5 inches wide, with ponies often at 4.5 to 5 inches and some larger horses at 5.5 to 6. To measure, put a smooth, thin dowel or a piece of string with a knot across the mouth, in the place where the bit sits, mark where it meets the corners of the lips and measure the distance between the marks. Add about a quarter of an inch (6 mm) in total for clearance, so the bit neither pinches nor slides. The Bit Size Calculator works this out for you.
How a bit should fit
- In a snaffle, there should be one or two wrinkles in the corners of the lips, which shows a snug but comfortable position.
- About a quarter-inch of clearance in total. A bit that is too wide slides from side to side, and one that is too narrow pinches the corners of the lips.
- The bit should not hit the teeth, and there should be a gap between the bit and the tush (canine tooth in males) or the bars where the tooth would be.
- Check that the bit lies flat over the tongue and that the horse is not trying to get its tongue over it.
The main bit families
| Type | How it works | Typical use |
|---|---|---|
| Snaffle | Direct pressure on the tongue, bars and corners of the mouth, with no leverage | Starting young horses, general riding, many English disciplines |
| Curb | Leverage through shanks, with a curb strap or chain, creating pressure at the poll, chin groove and mouth | Western riding, some advanced English work, with a trained horse and educated hands |
| Pelham and Kimblewick | Combine snaffle and curb action | Horses that need more control, with suitable hands |
| Bitless bridle | Pressure on the nose, jaw or poll, with no metal in the mouth | Horses with mouth problems, or riders who prefer it |
The Bit Finder asks about your horse, your riding and any mouth problems, and recommends the snaffle, curb or bitless family to try. A bit should not be used to compensate for a lack of training, and a harsher bit does not fix a lack of control.
Mouthpiece shapes and materials
- Single-jointed mouthpieces act in a nutcracker way on the tongue and bars, and some horses dislike them.
- Double-jointed (a middle link) distribute pressure more evenly and suit many horses.
- Mullen (straight) and ported mouthpieces give tongue relief.
- Thickness. Thicker mouthpieces are generally milder, but a thick bit in a small mouth can be uncomfortable.
- Materials. Stainless steel is durable; sweet iron and copper alloys encourage salivation; rubber and synthetic bits are soft.
Signs the bit is not working
- Head tossing, tongue lolling or the tongue over the bit.
- Gaping mouth, gnashing teeth or leaning on the bit.
- Rushing, evasiveness, or refusing to flex.
- Sores at the corners of the mouth, or bruising on the bars.
Behavior like this can also come from teeth problems, pain elsewhere or training, so ask a vet or equine dentist to check the horse's mouth at least once a year, and especially before changing bits. Sharp points, wolf teeth, and hooks on the molars are common reasons horses object to a bit.
Bitless options
Bitless bridles work through pressure on the face, and many horses go well in them. They can also suit horses with dental pain, injuries or a history of mouth trouble. They are not automatically gentler: poor hands can cause pressure on the nose and jaw, and cross-under and other designs work differently, so learn the one you use.
Cleaning and checking
Rinse the bit after each ride, and wash it with warm water regularly. Check the joints, rings and cheek pieces for wear, sharp edges and cracks, and check the leather and stitching on the reins and cheek straps.
Common mistakes
- Choosing bit size by guessing from the horse's height or breed.
- Moving to a stronger bit to solve a training problem.
- Ignoring teeth and mouth health.
- Using a curb bit with unsteady hands.
Frequently asked questions
What size bit does my horse need?
Most horses take a bit between 5 and 5.5 inches wide, but it varies. Measure the width of the mouth from corner to corner and add the allowance for your bit type. The Bit Size Calculator helps.
How many wrinkles should a horse have at the corner of the mouth?
One or two small wrinkles is a common sign of a good fit with a snaffle. No wrinkles can mean the bit is too wide, and many deep wrinkles can mean it is too narrow.
Is a bitless bridle better than a bit?
Neither is better for every horse. Bitless bridles suit horses with mouth problems and some riders, but they still apply pressure and need good hands and training.
Tools used in this guide
More guides
- How to Estimate Your Horse's Weight Without a Scale
- Feeding Horses: Hay, Grain and Supplements
- Body Condition Scoring with the Henneke Scale
- Deworming Strategy for Horses: Fecal Egg Counts and Targeted Treatment
- All HorseCalcs guides
Figures in this guide are general guidance for planning. Every horse is different, so work with your veterinarian, farrier or trainer on health, hoof and training decisions, and read our disclaimer.