Sizing of garment might vary based on seamstress but the general rule is for amaarutiit//snugglys you want to measure your bust, waist, and hips.
For aujaq amautiit you will want the same (bust, waist, and hips), but the waist measurement listed doesn’t have to be exactly to your own but rather a similar measurement to your hips as the opening goes around your hips. As an outerwear garment you will be wearing clothing and sometimes a small coat under to layer up. If the measurement is larger by a few inches but it’s listed as your size than it’s likely it will fit you.
For example, I (Ujarak) typically wear a size Medium and my waist measurement is 32” but the size Medium aujaq amaut that I make measure at (waist) 37” which is closer to my hip measurement which is 39”. The waist part of the amaut slips down and up my hips and the qaqungauti (tie) ties around the waist to secure baby in the amaut (pouch).