If you don’t wear your karate gi correctly, you will choose a uniform that is too small.
Pants are worn high on the body, with the waistband just above belly-button height. For drawstring pants pull them up to the correct height then pull the drawstring out to the sides, bunching the material at the back, then thread the drawstring through the loops to the front and tie them in a bow.
Jackets close left-over-right. Do up the left tie first, then the the right – this way the jacket will close more snugly around you. It’s OK to have the ties slightly loose on each side.
The belt sits on your hips, below the waistband of the pants to help hold them up. Wearing the belt too high will make you look out of proportion, and your pants might fall down! Put your belt on before you assess the fit of the jacket, in particular the length. A jacket worn without a belt will always look and feel too big.
On a new traditional cut uniform, expect to roll up the sleeves and pant legs. Uniforms can be shortened but wash it at least 10 times first to allow for shrinkage.