I recently found out about the multitude of day count conventions in Finance (e.g.wikipedia and stackexchange). As far as I understand the reason for this variety is a long history of diverse usage.

Would I be correct to expect that in the (perhaps near) future a global standard will emerge? If so is there any of the current conventions a good candidate for a global standard?

  • 3
    $\begingroup$ unfortunately most of the answer is encapsulated by xkcd.com/927 . Many of the day count conventions are there for practical as well as historical reasons. $\endgroup$
    – MD-Tech
    Jul 26, 2017 at 9:01

1 Answer 1



It is a detail that is important to get right, but otherwise uninteresting. There is no point in changing a convention once you've set one. There are some more common ones associated with the biggest markets, like Act/360, but that's all.

Day count conventions are well documented. There is a degree of consolidation via ISDA standard contracts in the IRS market, but it is limited.


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