In order to avoid shrinking the gi when washing, make sure you hand wash the uniform with cold water and let it air dry. If it takes more than twenty-four hours to dry the uniform, purchase two gis, so you don’t have to show up to the mat with wet clothes. BJJ gis shrink because they are made of cotton, which gets affected by hot water. Most modern washing machines use hot water, and even the ones that use lukewarm water have heat-producing dryers that evaporate the moisture. As a result, your gi will shrink if given a regular wash-and-dry treatment.