The planters are cylindrical so they are the same width from top to bottom and enhanced with uniformed ribbed banding.
Sizes (dimensions approx):
12cm diameter (external), 11 cm tall, takes a 10.5cm plant pot
14cm diameter (external), 13 cm tall, takes a 13cm plant pot
17cm diameter (external), 15 cm tall, takes a 15cm plant pot
19cm diameter (external), 18cm tall, takes a 18cm plant pot