A 20 inch wig is about 50.8 cm long. On many people, straight 20 inch hair falls around the chest or mid-back. But texture changes the visual length.
Straight vs curly
Straight hair shows the full length. Wavy hair looks slightly shorter. Curly hair can look several inches shorter because the curl pattern shrinks the drop.
How to measure
Measure from the crown area down to the ends while the hair is stretched gently. For curly wigs, length is often measured stretched, not in its natural curl state.
What to buy
If you want a true long-hair look in curls, consider going longer than 20 inches. If you want manageable everyday length, 20 inches is a versatile middle ground.
Bottom line
A 20 inch wig is long, but not waist-length for most wearers. Texture, height, and density change how long it appears.