How old was L when he became a detective? Well, that's what I'll be talking about in today's blog post! There may be some spoilers for Death Note in this post though, so proceed with caution! Now then, on with the post! So, how old was L when he became a detective? Well, it's actually hard to say; especially since we don't even know how old he was when he arrived at Wammy's House. Along with this, the manga and the anime never said how old he was when he arrived at Wammy's House. Even the one shots and Death Note 13: How To Read doesn't tell us about how old he was before. However, there were some clues in L: The Wammy's House. His initial appearance in this chapter suggests that he was quite young when he first arrived at Wammy's House, and Watari said L solved his first case several years after he had arrived. Although this isn't really a very helpful timeline, L's appearance in the later part of the chapter does suggest that he is most likely in his teens. Because of this, I would say it's safe to assume L was a teenager when he solved his first case. Even though that's a rather wide age range, it's kind of hard to pinpoint what his exact age was without more information. But, these are mostly just my thoughts on this topic. It's hard to say if we'll ever get to know exactly how old L was when he became a detective as well, since either Takeshi Obata or Tsugumi Ohba would have to confirm it for us. Nonetheless, I hope you guys still enjoyed this blog post! As a little bonus, I will also be including a picture of L below. Enjoy!