How much time has passed in-universe in Detective Conan? Detective Conan is a notoriously long-running series -- it's been running for like fifteen years, and hundreds of cases have been solved. Conan has made friends, received upgraded technology over time (cell phones!), and has generally "kept up" with its audience.

Yet, logically, time in-universe must have passed, and Shinichi's continued absence should be more notable than it is if he's been gone for more than a year.

How much time has passed, currently, in the Meitantei Conan universe?
Technically the story plays out in real time, but realistically it is at the whim of the author.

Assuming the cases appear in chronological order. You'll notice that none of the characters ever age or even graduate. There are many discrepancies the Eisuke/Kir Arc alone has some serious and problematic time discrepancies. It starts with the Nail and Snake Arc which took place a week or so after New Years and then continues to some cases later in the Clash of Red and Black arc which climaxing in a certain person's death. Eisuke vanished around 18th to 19th of December... so chronologically speaking a year should have passed... but did it? Ask Gosho Aoyama.