What are the sizes in mm of the average chin implants?

This depends upon the manufacturer, style and size. If you're concerned that your surgeon did not understand your desires you should return for further discussion. There are very straight forward measurements used to determine how much augmentation is required to create the ideal chin position. Ask your surgeon how much augmentation they are recommending and why. This should provide reassurance for you. Good luck. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

Chin implants are manufactured in a variety of sizes and shapes. Each manufacturer has different dimensions based on the sizes they manufacture. For more information, measurements,  diagrams and our chin implant photo  gallery, please see link and video below

It is hard to give you information regarding average sizes for chin implants.  There are many different styles, sizes, shapes and manufacturers.  There are also different sizes and styles for men and women.  If you place your finger from your lip straight down, your chin should almost touch your finger.