Question: what is the difference between c7 and c9 christmas bulbs?
Answer: C7 bulbs are the smaller than C9s. The have an E12 candelabra base, the same size as a night light bulb. ... C9 bulbs are larger, over 2 inches long, and fit an E17 base. They are available in 7 or 10 watts for incandescent bulbs and are generally used in the same ways as a C7 bulb.