There are various theories to explain this particular unit of measurement, according to one of these all depends on the pulmonary force of the ancient glass blowing glass makers.
According to this theory, when in 1700 the importance of storing wine in glass began to be understood, the blowers managed to blow bottles no larger than 65-75 cl, so since people were looking for the largest recipient, it was decided for 75 cl bottles.
According to some other theories, it depends on the fact that a bottle of this size contains exactly 6 glasses of 125 ml used in taverns.
Still others argue that this unit comes from the British who measured volume in imperial gallons. Each case of wine could contain only 2 gallons (9 liters) and the English decided to enter 12 bottles for each box … 0.75 for each bottle!