Since hair loss can be progressive, it is important that you retake and record these measurements every six months. This is to ensure you are wearing the correct base size and prevent any damage to your biological hair which can be caused by wearing the wrong size. Here are some topper recommendations for different stages of hair loss:
If you have thin hair in the front/hairline or an obvious thinning top, a 5.5" X 5.5" topper would be a great option for you.
If you have thinning top & crown, a large coverage hair topper would be a great choice as it is able to provide more coverage and add instant hair volume.
If you have a receding hairline or baldness in the front, a lace front hair topper or a hair topper with bangs would be better.