Grades at Hogwarts

The grading scale for Hogwarts classes, Ordinary Wizarding Level (O.W.L.) exams, Nastily Exhausting Wizarding Test Level (N.E.W.T.) exams, and the Wizards’ Ordinary Magic and Basic Aptitude Test (W.O.M.B.A.T.) are as follows (HBP5):

Pass Grades:
Outstanding (O)
Exceeds Expectations (E)
Acceptable (A)

Fail Grades:
Poor (P)
Dreadful (D)
Troll (T)

On the W.O.M.B.A.T. test the Grades are further explained (JKR:W1):

• Outstanding – CONGRATULATIONS! Your exemplary powers of deduction and a formidable knowledge of the inner workings of the magical world reveal you to be a witch or wizard of genuine skill and learning.
• Exceeds Expectations – Well done – a most creditable performance!
• Acceptable – demonstrates real magical potential.
• Poor – Alas – we regret to inform you that you have narrowly failed. This may have been due to factors outside your control (eg: poltergeist intervention, examination nerves or a malfunctioning quill.) Please do not disconsolate.
• Dreadful – We are sorry to inform you that you have failed.
• Troll – You would appear either to have abandoned the test due to factors outside your control (eg, earthquake, poltergeist attack), or else you are a troll, in which case you are to be congratulated on being able to use a computer and have achieved the grade of O.F.T. (Outstanding for Trolls).

These distinctions are clearer when put into action, as when Snape graded the fifth-year potions essay on Moonstone as if it was part of the O.W.L. exam (OP15). When he handed them back, he said most of the class “would have failed” their O.W.L. exams.  Hermione made an EE for Exceeds Expectations, which she accepted as a “baseline” for improving to an Outstanding. Draco must have done well, because he laughed at the thought of anyone making a “Dreadful,” which is unfortunately what Harry received in the form of a “spiky D” on his paper. Ron made a P for “Poor,” which was higher than Harry’s grade, but still considered a failure by O.W.L. standards.

However, Harry did quite well on his O.W.L. results (HBP5), except for classes he found dull, like History of Magic and Divination. In Potions he made the same grade as classes he enjoyed, such as Herbology or Care of Magical Creatures.

• Astronomy A
• Care of Magical Creatures E
• Charms E
• Defense Against the Dark Arts O
• Divination P
• Herbology E
• History of Magic D
• Potions E
• Transfiguration E

Occasionally grades are given in numerical values or percents:

• Hermione received a 320 percent score in Muggle Studies, before dropping the class (PA22).
• Hermione made 120 percent on a Charms test once (OP30).
• When Harry's Confusing Concoction wouldn't thicken, he saw Snape write "something that looked suspiciously like a zero onto his notes before moving away" (PA16).
• Harry assumed he made a "zero for the day" when he left Hellebore out of the Draught of Peace (OP12)
• When Harry made an Invigoration Draught in Potions class, he thought he did pretty well until the flask got broken and Hermione cleaned the rest of it out of his cauldron. Snape, who was angry at Harry anyway for sneaking a peek into his Pensieve memories, gave him a zero for the task (OP29)
• Harry received a "bonus point" for creating a corporeal Patronus during his DADA O.W.L. exam (OP30).