What is the average age to become a grandmaster? On average, what is the age of people when they obtain the title of international master or grandmaster? I also wonder how the age distribution looks like.
Brilliant little data mining project!

I used the wiki list of GMs and wrote a quick and dirty script to extract the data. Feel free to use and expand/alter it, if you are interested.

As it turns out, the average age for reaching GM is just above 28. It is, however, skewed by "old" generation players and players from time before GM title was a thing. It was officially introduced in 1950 and some (old) players were awarded it at the time. It is intriguing to look at average age in different generations of players. And so:


For players born after 1945, the average is slightly above 26 years old. 
For players born after 1970, the average is slightly above 23 years old. 
For players born after 1975, the average is slightly above 22 years old. 
For players born after 1980, the average is 21 years old. 
For players born after 1985, the average is just shy of 20 years old. 
For players born after 1990, the average is 18.5 years old.


Clearly, on average, people are becoming a GM faster nowadays! The age distribution (for players born after 1945) is as follows:


In case it is of interest, the two countries "producing" GMs on average at lowest age are India and China - both at 21 years old. Countries with most GMs (all time) are Russia (by huge margin), Ukraine, Germany, USA and Hungary.