How many languages in the world are unwritten?

The exact number of unwritten languages is hard to determine. Ethnologue (21st edition) has data to indicate that of the currently listed 7,111 living languages, 3,995 have a developed writing system. We don't always know, however, if the existing writing systems are widely used. That is, while an alphabet may exist there may not be very many people who are literate and actually using the alphabet. The remaining 3,116 are likely unwritten.