Is there an enchantment on the room making it unplottable, or did the Marauders never find it?


2 Answers 2


We don't know.

Hermione and Ron offer differing (but not necessarily contradictory) explanations for why it's not on the map. Hermione surmises that unplottability may be one of the charms that the room casts when it's being used by someone who doesn't want to be found whereas Ron's suggestion is that it may not be on the map because the Marauders didn't know about it.

Since we know that the map only shows rooms and passageways that were known to the Marauders (hence the Chamber of Secrets not showing up) there's a distinct possibility that they're both right; that it's not on the map because the Marauders didn't know about it, but that even if they had, they wouldn't have been able to add it to the map because it has its own cloaking spells.

‘The Room of Requirement!’ said Harry, smacking himself hard on the forehead with Advanced Potion-Making. Hermione and Ron stared at him. ‘That’s where he’s been sneaking off to! That’s where he’s doing … whatever he’s doing! And I bet that’s why he’s been disappearing off the map – come to think of it, I’ve never seen the Room of Requirement on there!’
‘Maybe the Marauders never knew the Room was there,’ said Ron.
‘I think it’ll be part of the magic of the Room,’ said Hermione. ‘If you need it to be unplottable, it will be.’
‘Dobby, have you managed to get in to have a look at what Malfoy’s doing?’ said Harry eagerly.

Harry Potter and the Half-Blood Prince

We do know that it doesn't show up at other times (if we presume that Harry has looked at the map other than when Malfoy is in it) suggesting that Hermione may be wrong that it's only unplottable when needed, more likely it's unplottable at all times.

  • 1
    I think, rather than always being Unplottable, it simply doesn't exist when it's not in use. The Room probably intentionally shows up on maps when it's opened with the intent that it be found, but that's a bit rarer than it being called to help someone hide. Mar 30, 2016 at 1:05
  • Yet despite this passage, there seems to be a prevailing opinion among people online that the entire Hogwarts is always unplottable. Not sure where people got that from.
    – ibid
    Feb 5, 2017 at 5:16
  • I can understand the unplottable aspect being applied to the room of requirement simply because it may act like a moving/portable pocket universe within the spaces of the castle, but the castle seems stationary, no? Dec 23, 2018 at 19:41
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    @DarthLocke - anything can be made unplottable, it seems. Tbh eventually you just have to throw up your hands and say "well, that's how magic works"
    – Valorum
    Dec 23, 2018 at 19:53
  • @Valorum Ya, I see what you mean. Dec 23, 2018 at 20:15

I think the Marauders couldn't draw the room of requirement because the room would change shape and size according to the people who use it. It could be a broom cupboard like when Fred and George are hiding from Flich, or a perfect place for the DA, which is very different in size

  • So I do not completely disagree, but I do disagree
    – user134109
    Nov 15, 2020 at 17:33
  • 1
    Welcome to SciFi.SE! I'm not sure what you're referring to when you say you "disagree", but this is a very good point.
    – F1Krazy
    Nov 15, 2020 at 17:34

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