This pattern was created for myself, and admittedly, I have larger arms than most women probably do. Since this is my first pattern I’ve written, and I’m by no means an expert, all I can do is assume you can adjust the size one of two ways:

Use a smaller/larger hook, -or-

use fewer or more rows to create the initial band to fit snugly around the section of your arm the top most end of the arm warmer will be.

Enjoy =)