How to tie a neckline so that it can fit over the head, doesn't hang loosely around the neck, and has a beautiful round shape?

There is a simple algorithm for this. It is so universal that it can be used for calculating stitches for knitting necklines for both adult and children's clothing from various types of yarn.

This calculation is provided for forming a classic round neckline. But you can deepen and widen it - the design of the rounded areas will remain the same.

The whole method fits into two pictures-schemes, where an example is given with a specific knitting density.

To apply this method, you need to know the width of the neckline and its depth (this depends on your measurements and the chosen model). In the scheme, I provide standard width and depth for an adult.