Gavin Andresen - 2013-01-17 16:11:17

We can calculate the minimum unit from following algorithm:

Code:
# [Total value] = all Dollars in circulation + Euros in circulation + Yens in circulation + CNY in circulation + all the other currencies
# Convert [Total value] to amount of smallest units/fractions of the earth's cheapest currency (*excluding* internet currencies and currencies of countries with hyperinflation)
# Add one or 2 zeros.
There you have it. The humanity will probably never require more units of Bitcoin than that, even if Bitcoin becomes #1 World currency and everybody on the world starts using Bitcoin instead of other currencies.

Currently, total amount of the smallest units of Bitcoin is 2,100,000,000,000,000 which is just over 2 thousands of trillions (USA scale). Is it enough according to the equation above ? I highly doubt so.

Let me google that for you.... ah, here's a nice chart:
  http://dollardaze.org/blog/?post_id

There is about 5 trillion dollars in currency in the world.

So 2.1 thousand trillion satoshis is PLENTY.