I posted a question an hour ago and My achievements section shows activity “yesterday” and then activity “today”. Is this a bug? I understand someone in a diff timezone my have left feedback but I wouldn’t expect the time stamp to say yesterday

my achievements in iOS app

Fully aware I can’t up-vote my own question, I did so anyway when I saw someone Down-voted it without leaving any feedback. I got a pop up saying I can’t up-vote my own question. I’m not sure if this has any impact on said achievements behavior.

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    "Yesterday" was only about 50 minutes ago, UTC time. Could that explain the situation?
    – Jeff Schaller Mod
    May 25, 2020 at 0:50
  • @JeffSchaller I suppose it does. I feel like that places a burden on the user to know what UTC is and how it applies to where they live. I feel the more intuitive solution is to have activity time stamped relative to the users local time. Thanks for the explanation.
    – Niko_Jako
    May 25, 2020 at 1:19
  • Clicking on the trophy achievement icon uncovers the site's current time, in case it helps.
    – Jeff Schaller Mod
    May 25, 2020 at 1:46
  • @Niko_Jako if you had the time different for every user, it would be impossible to communicate anything to do with the time something happened on the site since everyone would need to translate to some other time zone. This way, all times across all pages of the network are always on UTC so everyone has the exact same timestamp. It really simplifies things.
    – terdon Mod
    May 25, 2020 at 11:31
  • ...and translating "to some other time zone" may even be impossible: users may want not to disclose their own time zones and the system isn't able to reliably infer a user's time zone in order to suggest other users how to translate time designations.
    – fra-san
    May 25, 2020 at 12:40

1 Answer 1


A "day" on Stack Exchange starts at 00:00 UTC time.

I believe "Achievements" are shown in absolute UTC days to keep them consistent to the way time spans for caps (to daily reputation, votes...), badges and possibly other things are calculated.

There have been requests for that definition to be changed, or for the displayed times to be made more consistent to the user's local time. For instance, on the main Meta:

They all have been declined, and others have been closed as duplicates of them. I could not find any official statement but, based on some of the answers to those questions, it seemingly happened out of concerns about implementation complexity, the chances to game the system that a localized definition of "day" would open up and the amount of work reasonably needed to mitigate them.

Note that relative times (e.g. "yesterday") that are not relevant to achievements, such as those shown at the bottom of posts in place of timestamps, are not relative to the UTC date: "yesterday" is defined as "more than 24 and less than 48 hours ago".

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