In general, straight hair is longer than curly hair, because it lies completely flat when we measured. If you choose curly hair extensions, it is ideal to choose one size longer that you would. Also, curly hair extensions tend to look heavier than straight hair when you wear them. Straight Virgin hair, true to its length, so buy the size as you wanted. Wavy hair is usually 1.5" shorter (unstraightened), Curly hair is usually 3.0" shorter than Straight hair. We often suggest customers to purchase hair 2" longer if they desire a Curly hair look.If your natural hair is very short, you'd better choose the length under 18 inch, or you would feel uncomfortable. and if you have medium to long hair, it is ideal to wear long hair extensions.