There are too many sizing standards in the world for anyone to keep up with, hence, they’re irrelevant.
Morphí sizes are labeled with letters instead of numbers. This requires you to look for what size to sew based on your actual body measurements – the most important when you’re sewing clothes that fit.
Free yourself from the Ready-To-Wear vanity sizing charts.
Make it a habit to take your measurements regularly, and at least every time you try a new pattern brand. Get it right, and rock your sewing.