The “bag” of the bagpipe has the sole function to be a reservoir for a constant supply of air under pressure that keeps all reeds vibrating at optimum. Once upon a time, it was thought that the more air in the reservoir of the bag meant better sound. As a result, playing as big a bag as possible was a step in that direction. This was a product of the emerging pipe band movement in Scotland that had pipe bands looking for the “big sound” that would give them an edge over their competitors. Many players today continue with this misguided logic, especially in pipe bands. Solo pipers though, had it right all along: Play a bag that is smaller and suited to your stature and comfort.
Pipe bags are generally made in small, medium (regular), and large sizes. All bag sizes, like people, are slightly different from maker to maker. A medium size bag in sheepskin from one maker might be slightly different than a medium goatskin bag from another maker. A small synthetic bag will not have the exact same size and circumference as a small hide bag. Many makers also will make extra-small or extra-large bags for those pipers needing those.
Any bag you choose will need to accommodate your individual size and posture. Playing a bag that is too big or small will severely impact your ability to play the instrument. Ergonomics are key. One must be able to comfortably reach around the inflated bag with the left arm and grip the chanter’s top hand notes in a smooth plane from elbow to fingers, perpendicular, or very nearly, to the body. The fingers should move with little or no resistance or tension while in a comfortable stance. A bag that is too large for you, or too small, will distend your left wrist introducing tension in the hand and perhaps forcing the shoulder to dip or rise unnaturally during play. If your wrist needs to bend to grip the chanter, or your arm and hand reach the chanter at an upward or downward angle, your pipe bag may be the wrong size for you. As a rule of thumb, if you develop strain or tension in your left arm, shoulder, or hand while playing, the bag could be the wrong size for you. Experiment and try different sizes and makes of bags on the instruments of your fellow pipers to find one that feels like it is the right fit.
Generally, an average-sized human (approximately 5’6” to 5’11”) will not need a bag that is any larger than a regular, or medium bag. Someone who is taller than average should move toward a large size bag. Some taller pipers find that using a medium size bag allows greater freedom of movement in the arm and hands. The same is true for pipers of average height. Average size pipers might find a small size bag allows greater comfort and movement. Shorter pipers should consider nothing larger than medium for optimal comfort. Again, experiment and try different bags at different sizes if you are looking for a change.