Measuring Your Horse for the Correct Bit Size

Selecting the right bit size is as important as choosing the right type of bit. A correctly sized bit ensures comfort, clear communication, and prevents mouth injuries.

Why bit sizing matters

• Comfort: A bit that is too small pinches lips and cheeks; too large slides excessively.
• Clarity: Proper sizing allows the bit to sit evenly across the bars and tongue.
• Safety: Ill-fitted bits can create sores, bruising, or encourage evasions.

Step-by-step methods for measuring

Using a hardwood dowel

• Choose a smooth, round dowel about 1.5 cm thick, longer than the horse's mouth.
• Insert gently into the mouth at the level where the bit would sit.
• With the dowel centered, mark each side at the outer lip corners.
• Remove and measure the distance between marks with a ruler or tape.

Differences in sizing by cheekpiece style

Loose ring bits:

• Require slightly more length (about 5 mm extra each side).
• Rings move freely, so extra width reduces pinching of lips.
• Example: If the mouth measures 135 mm, a 140 mm loose ring may be appropriate.

Eggbutt bits:

• More stable, fixed cheeks.
• Do not need extra width; size should match the mouth measurement closely.
• Example: A 135 mm mouth measurement usually fits a 135 mm eggbutt.

Mouthpiece style and its effect on fit

Jointed bits (single or double):

Collapse in the mouth and can be considerably longer than the measurement but still appear to fit well from the outside.

Solid bits (mullen, straight bar, ported):

Do not collapse, so they maintain full width. Can be fitted closer to the exact mouth measurement.

Final note

Accurate measurement prevents discomfort and resistance, ensuring your horse can respond calmly and clearly to rein aids. A well-fitted bit is a cornerstone of good horsemanship.