Re: Is there an accurate way to calculate the number of Bitcoin users
LoyceV says there are about 36 million funded addresses, which means that the number of Bitcoin users is much smaller than that.
That is assuming that there is an insignificant amount of users holding their Bitcoins at exchanges and services.Can this number be accurate, especially since the number of users of this forum, Reddit and others equals 5 million users, and if each user has 10 addresses, the number of Bitcoin funded addresses must be higher than 50 million. 
No. You cannot assume that the active users on Reddit and Bitcointalk are all holding any amount of Bitcoins. Some users may very well just be participating in the discussion or are interested in holding coins other than Bitcoin. There really isn't any way to calculate the number of unique Bitcoin users due to how its structured.