The length of your hair extension depends on the purpose or reason you are using it. For example, if you have short hair and you want it to look fuller and thicker naturally, you must go for a hair extension with a length of about 6 to 7 inches. This length will help you dab those extensions like natural hair without leaving a hint of artificiality. However, if you intend to adopt a new style or haircut without cutting short your naturally long hair, you can style them with short length wigs. By doing so, you can get back to your natural hair length whenever you wish for.