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Bomber Bit Sizing Chart & Fitting Guide - How to measure a horse bit

Bomber Bit Sizing: To measure the mouthpiece, take the length from the outside of the horse's lip on one side to the outside of the other. To make this easier, consider using the Bombers Bit Measure.

Measure in millimetres on the mouthpiece of the bit ONLY (i.e. measure the length of the blue mouthpiece pictured below, not including any of the silver cheekpieces). The bit photographed is a 135mm bit. 

how to measure a Bomber bit for your horse

This video shows exactly how to measure:


Bomber Bits should fit snugly, with no gaps between the lip and the start of the cheekpiece. They should sit flat against the lips, not squeeze the lips in.

  • Measurements are taken of the mouth from just outside one lip to another (i.e. measure to the inside of the cheekpieces). For example, from inside the Tbar on one side to the inside of the other.
  • The easiest way to do this is to measure against a bit with a straight mouthpiece (such as a Mullen mouth) 
  • It is noted that throughbreds are being bred with finer mouths than ever, and having polo ponies fit small or even extra small bits is not uncommon

The sizing chart below shows the standard sizes for straight Bomber bits used on Buttery Horse Co:  Small (120mm) Medium (125mm) and Large (130mm) for most 15hh-15.3hh Thoroughbred polo ponies in Australia. Larger warmbloods, eventers and hunters who have thicker lips and wider jaws may need 135-145mm. A few thoroughbred polo ponies will need Extra Small (115mm), which can also be ordered as a custom size. Our standard sizes include the following variations:

  • Bit rubbers may take up an extra 3-5mm
  • Control plates and other broken (3-piece) Bomber bits sit over the horse's tongue rather than straight in the mouth, so need an extra 5-10mm. This is included in our standard sizing. 
  • Solid mouthpiece bits such as the Happy Tongue, Mullen or ported bar bits are slightly more forgiving if the bit is too big, but it will not be ideal because when you turn, the bit will shift in the horse's mouth. 

Bombers says:When the mouthpiece is too large, the bit joins move and the curves can sit incorrectly in the mouth. This leads to the mouthpiece applying pressure in areas it should not be. An oversized bit will also create too much movement in the mouth, allowing the bit to slide from side to side within the mouth. This movement causes discomfot as well as background noise to the riders aids. 

Bomber Bit Size Chart for 15hh-15.3 Australian Thoroughbred Polo Ponies

Size (inches)

from lip to lip (do not include the cheeekpiece in measurement) 

Bombers Bit Size (mm)

(Sizes are for a straight bit - for broken bit add 10mm and for bit rubbers add 3-5mm)

Bomber Bit Sizes

used as standard on Buttery Horse Co.  

4.5 inches 115mm Extra Small
4.7 inches 120mm Small
4.9 inches 125mm Medium
5.1 inches 130mm Large
5.3 inches 135mm Extra Large
5.5 inches 140mm



Bomber Bit Guide: There are many variations to consider when fitting the perfect bit for your horse. Bomber bit favourites include the Happy Tongue and Bomber Blue as good starting points, with the Control Plate and Pelham stronger options. The below Bomber Bit catalogue explains in detail. Feel free to write to us if you have questions. GavSays is the Bombers bit fitting guru and we highly recommend his videos. 

Choose and fit the perfect bit for your horse
Bomber bit catalogue for custom horse bits

Polo Bomber Bit Catalogue:

Polo Catalogue


GavSays Bomber Bit Tutorials