I haven’t seen any sort of estimate for some time. Back around 2010/11 when the dinar dealers were in their heyday it was estimated that approximately two thirds was outside the country, around 20 trillion…Obviously without any factual basis and some of the theories about who actually has dinar is questionable.

The one thing that we do know is that in 2003 it took around 6.5 trillion new dinar to replace the old so a good indication of how much was in Iraq at the end of 2003…The rise in the amount of currency in circulation has far exceeded the rise in population and it should be borne in mind that currency that has migrated across local borders is still outside Iraq.
I would not think it unreasonable for somewhere in the order of 50/60 percent of the currency to be outside the country. If that were the case I can see it being a major headache in terms of a redenomination. There could be severe repercussions if Iraq were to say that the IQD can only be exchanged in Iraq.