Length: ~17.5 inches. Slightly stretchable due to middle smocked column at the back.
 
Remaining sizes available (measurements when item is laid flat):
Size XXS: PTP 14-15 inches, waist 12-12.5 inches
Size XS: PTP 15.5-16.5 inches, waist 13.5-14 inches
Size L: PTP 18-19 inches, waist 15.5-16 inches
Size XL: PTP 19.5 inches, waist 17.5 inches