14 to 16 cm is acceptable size and its generally the standard number retailers use. Bulbs will be at least that size or larger even tho they list them as 14 to 16 cm. Trumpet lily bulbs, by nature are larger and you might see them listed as 18/20 or 20+ cm. To me, the quality of the bulb is more important than size--how solid and tight the scales are, how heavy, how fresh, etc.
