I was doing some research for this question, and that brought to my attention something that doesn't add up.

According to Half-Blood Prince, Hermione achieved eleven OWLs:

'Oh, come off it,' said Ron, striding over to her and whipping her results out of her hand. 'Yep - ten "Outstandings" and one "Exceeds Expectations" in Defence Against the Dark Arts.'

Half-Blood Prince Chapter 5: "An Excess of Phlegm"

According to Pottermore, there are twelve OWL subjects:

  1. Transfiguration
  2. Charms
  3. Potions
  4. History of Magic
  5. Defence Against the Dark Arts
  6. Astronomy
  7. Herbology
  8. Arithmancy
  9. Muggle Studies
  10. Divination
  11. Study of Ancient Runes
  12. Care of Magical Creatures

Of these, Hermione was taking ten in fifth year: she dramatically drops Divination about midway through Prisoner of Azkaban, and she says at the end of that book that she dropped Muggle Studies.

We can confirm this number, since Harry's OWL results (And complete class list) is printed earlier in the chapter: he's taking nine courses. We know Hermione is taking Ancient Runes and Arithmancy (She frets about how she screwed up the exams for those courses earlier still), and she's not taking Divination; otherwise, their classes are identical.

So how did she get eleven OWLs? I could accept that she'd be able to write the exam without taking the class (And pass with flying colours; it is Hermione, after all), and for Muggle Studies I'd take that as valid, but it seems like something she'd dismiss as being "Too easy" - the reason she dropped the course in the first place.

Honestly I suspect the answer comes down to "JKR sucks at math", but I was curious if this had ever been addressed in canon.

  • What about Numerology? I remember Hermione taking in the third book.
    – user64144
    Apr 3, 2016 at 1:02
  • 2
    @Stephanie Hermione refers to one of her textbooks, Numerology and Gramatica; that's the only reference to Numerology in the book, so it's probably what you're remembering Apr 3, 2016 at 2:29
  • 2
    My first thought was that she could have taken the exam without having taken the class--you can do that with AP exams where I go to school--but I'm not overly familiar with the inner workings of the HP universe, so this could be wrong.
    – Pleiades
    Feb 22, 2018 at 16:18
  • Another possibility is that one subject may have more that one exam/qualification associated with it. As a real world example I sat exams for GCSEs in English Language and English Literature, but both were taught in "English" lessons.
    – Kaz
    Aug 6, 2019 at 18:54
  • @JasonBaker do you mean arithmancy?
    – ava
    Nov 16, 2021 at 14:07

2 Answers 2


Where, exactly, does it say that she got twelve O.W.L.s?

This is what my copy of Half-Blood Prince says:

“Oh, come off it,” said Ron, striding over to [Hermione] and whipping her results out of her hand. “Yep – nine “Outstandings” and one “Exceeds Expectations” in Defence Against the Dark Arts.” He looked down at her, half-amused, half-exasperated. “You’re actually disappointed, aren’t you?”

That makes ten OWLs, which is entirely consistent with the known subject list.

It seems I might have spoken too soon. I’m using a fairly recent British edition of the book, but other printings (including the OP’s – see comments) disagree. The HP Wiki article on O.W.L.’s states:

In early editions of Harry Potter and the Half-Blood Prince, Hermione Granger is said to receive eleven O.W.L.s, scoring ten O's and one E. However, after the events of Harry Potter and the Prisoner of Azkaban, Hermione shrunk her class load from twelve subjects to ten, dropping both Divination and Muggle Studies. This was corrected in the Scholastic edition, where Ron instead states the she received nine O's and one E, giving her a total of ten O.W.L.s.

This version of events is backed up by the following article:

Publishers have been forced to correct an error in one of JK Rowling's Harry Potter blockbusters.

The hardback edition of the sixth instalment of the schoolboy wizard's adventures, Harry Potter and the Half-Blood Prince, said that swotty Hermione Granger had scooped 11 top results in her Ordinary Wizarding Levels (OWLs). But hawk-eyed readers spotted that in the previous book, Harry Potter and the Order of the Phoenix, she had only taken 10 subjects.

Publishers quickly fixed the discrepancy in the next edition, downgrading her results from one "Exceeds Expectations" and ten "Outstanding" grades to nine "Outstandings" and one "Exceeds Expectations".

The change in the Harry Potter books was reported on fan site www.mugglenet.com.

A spokeswoman for publishers Bloomsbury said that the error had been spotted last year and quickly fixed.

"In book six it said 11 and book five it said 10," she explained.

"It was corrected immediately."

("Potter Book's OWL-ing Error Fixed", The Yorkshire Post, 2nd September 2006).

This in turn seems consistent with my and the OP’s experience. Chalk this one up to JKR’s dodgy maths.

  • 13
    Fair enough; inconsistencies abound when we make JKR do addition, so that's a fair answer Nov 21, 2014 at 18:33
  • 3
    Why are you using information that does not provide a citation? You know the Wiki is sub par -- the lack of a citation on info from the Wiki is kind of a big deal. I'm surprised! Nov 21, 2014 at 18:37
  • 5
    The most recent British version from the Pottermore Shop also corrects the mistake; nine outstandings + one exceeds expectations. Nov 22, 2014 at 8:00
  • 5
    I wonder why she couldn't have simply taken the OWL exam for Muggle Studies without having finished the course. She should have passed with ease. It's like a native language speaker taking courses in their language at a foreign university; it happens all the time. Oct 4, 2015 at 4:37
  • 4
    @JasonPatterson Except taking exams without taking classes is generally a university thing. In primary and secondary schools (like Hogwarts), classes and exams usually go together, mandatorily. Drop the classes and you also drop the exam. It could be that Hogwarts doesn't work this way and Hermione could and did take the Muggle Study exam without the classes; but the fact that it was changed in recent prints of the book would indicate that this is not in fact the case. Oct 4, 2015 at 21:40

Ok so JKR was right and there are 11 O.W.L.s. Allow me to explain...

Okay so first you need to take into account all the subjects taught at Hogwarts:

  1. Transfiguration
  2. Charms
  3. Potions
  4. History of Magic
  5. Defence Against the Dark Arts
  6. Astronomy
  7. Herbology
  8. Arithmancy
  9. Muggle Studies
  10. Divination
  11. Study of Ancient Runes
  12. Care of Magical Creatures
  13. Alchemy

Alchemy is stated as an official optional subject at Hogwarts.

There are 13 subjects that Hermione had taken at the start of the 3rd year or something, listed above.

She quit Muggle Studies and Divination: 13 - 2 = 11, as JKR said.

  1. Transfiguration : O
  2. Charms : O
  3. Potions : O
  4. History of Magic : O
  5. Defence Against the Dark Arts : E
  6. Astronomy : O
  7. Herbology : O
  8. Arithmancy : O
  9. Muggle Studies : QUIT
  10. Divination : QUIT
  11. Study of Ancient Runes : O
  12. Care of Magical Creatures : O
  13. Alchemy : O

'Oh, come off it,' said Ron, striding over to her and whipping her results out of her hand. 'Yep - ten "Outstanding" and one "Exceeds Expectations" in Defence Against the Dark Arts.'

  • I did leave out Ghoul studies because of isn't that something you would learn in DADA? I don't know but I just felt that it was too unrealistic to be considered as other subjects can cover this topic. There is also Magical Theory but it said to probably be only for first years. Jan 5, 2018 at 21:28
  • 3
    Can you add a citation for Alchemy being listed? Jan 5, 2018 at 21:29
  • 7
    You can't get an OWL in Alchemy as it is only offered in years 6 and 7.
    – Skooba
    Jan 5, 2018 at 22:16
  • 2
    Of the several flaws with this theory, the one that bothers me the most: if Hermione were taking another class, I'd expect it would get brought up occasionally. Of course she shares most of her classes with Harry and Ron, and both Runes and Arithmancy get mentioned regularly (often because she's doing homework, or complaining about the exams), but there's absolutely no mention of any other classes Jan 5, 2018 at 22:38
  • We know Hermione wasn't taking care of magical creatures. Harry, Ron and Hermione all dropped it because Hagrid was such a terrible teacher. Mar 23, 2022 at 18:24

Not the answer you're looking for? Browse other questions tagged or ask your own question.