And never forget that the value of the half cent, when it was discontinued in 1857, was equivalent to about 14 cents in today's money. But don't even think of discontinuing the penny, or nickel, or dime!
You need to be more specific. Do you mean the coin with the lowest number written on it, the lowest value of coin minted in a country in a given year, or the lowest division of a major unit such as a dollar? In the UK we minted a quarter farthing. From Jersey I have a 1/52 shilling.
I think a more interesting question would focus on the lowest valued coin in circulation, accounting for inflation. Quite a few contenders in that category, I'd imagine!
Technically, not "coins." I am not happy with the standard definition. I believe that true knowledge is often more complicated than the Orwellian declarations we shout on cue. My sensibilities aside, the fact is that following the late Alan Herbert who argued the point long and well, a coin is issued by a governmental authority and is accepted in indirect barter as money, where money is anything you accept now with the intention to trade later for something else. Thus, tax tokens are indeed, "tokens." They stand for money with limited use, in this case certain retailers in certain US states for a short period of time when balancing their obligations for retail sales tax. That being as it may, personally, I agree with you. 12 pence to the shilling; 20 shillings to the pound. So, 1/4 farthing is a 1/16 penny or 1/3840 of a pound or, say, 1/8 of a US cent... But unlike a tax token, coined money according to the numismatic hobby in the USA. Ah, yes! The entire family of protot (plural of prutah), the small coppers of Hellenistic Jewish kingdoms. They were also called by their Greek name: lepton (plural leptoi?). The word means "lightweight" or "small" and is the same name given to the subatomic particles including the nutrino.
I read somewhere that the Turkish 1 kurus was the lowest value coin of modern times, but my memory is suspect...
I was on a bus in s Korea in 1980 and I saw a coin on the floor. I put my foot on it before someone saw it then cool like pick it up then I saw it was a 1 won worth 1/7 of a us cent . I gave it a flip back to the bus floor.
In Japan, when the Meiji era monetary reforms were put in place the old 1 min coppers were set at a value of 10 to 1 sen. With 100 sen = 1 yen each old coin was worth 1/1000 Yen. They were never officially demonetized and now 100 Yen = approx $0.95, that would make them worth a current value of roughly $0.000095 each.
Please be more specific in your question. Coins, paper, colonial currency, world, US, etc. There are a lot of different answers for this question.
I notice several references to “adjusting for inflation.” Doing so with relative values of different coins from different economies at different times in history would be inaccurate tomfoolery. All countries have not had the same inflation rate. FYI, I expect to get plenty of blowback on this point, especially from those who want to adjust every price and value figure in existence.
Currently, the Philippine centavo, Trinidad & Tobago cent, and Turkish kurus are the lowest I can think of, at about .2 US cents or slightly less.