The importance of the number 7 in Harry Potter

Since Antiquity, and in many civilizations, the number 7 has been considered a magic, sacred number. It is therefore not surprising that JK Rowling slipped this number many times throughout the saga, sometimes in an obvious way, other times in a much more subtle way.

The 7 as a simple figurative number

Among the appearances of the 7, the most visible are those where this number appears literally. These include the only two known Gringotts chests, 687 (Harry’s) and 713 (the one housing the philosopher’s stone). Other examples, Harry’s wand measures 27.5cm and costs 7 Galleons. When Hermione first brings up the Alohomora Spell, she indicates that it is in Chapter 7 of the manual. In The Prisoner of Azkaban, Arthur Weasley wins 700 Galleons thanks to the Daily Prophet. There are 700 possible fouls in Quidditch. In one of his visions, Harry sees Sirius being tortured by Voldemort in aisle 97 of the Hall of Prophecies in the Department of Mysteries. In the movies, the Hogwarts Express is number 5972.

Mysterious Vault 713 at Gringotts

For all these examples, the 7 does not bring any particular importance, it could be replaced by any other number. Its presence therefore illustrates that, even without impact or reason, this figure has a magical side.

Age, date and arithmancy

Age in the wizarding world is important, and accompanies the major stages of life: it is in particular at the age of seven that the first magical powers are revealed in young wizards, and the majority of witches are acquired at 17 years old. The 7 also appears in magical creatures, for example the unicorn: it is indeed at the age of seven that the latter become completely white, and therefore adults.

The dates also reveal certain secrets. If some are easy to pierce, like Harry born in the seventh month of the year, others are more discreet and can be revealed with arithmancy…

1664482082 898 The importance of the number 7 in Harry Potter
The arithmancy teacher
at Hogwarts, Septima Vector

Arithmancy is a technique of divination, based on the numbers from 1 to 9. The professor of this subject at Hogwarts is named Sevenimage Vector; we therefore find the magic number in his first name. The latter may also come from Septimus Tripoli, the inventor of the only alphabet used in arithmancy to transform letters into numbers. Among the known arithmancers, we can cite Brigitte Wenlocka 13th-century witch, who was the first to discover the properties of the number 7 !

So much for the theory, now let’s move on to practice: and if you were told that certain figures or certain dates, a priori trivial, were actually hiding the magic number? See instead:

  • Voldemort was born on December 31: an interesting date, border between the end and the beginning. But here’s what we can get out of it: December 31 = 12/31, so 3+1+1+2 = 7! And it doesn’t stop there; Voldemort was born in 1926: so let’s add up all the digits of his date of birth: 3+1+1+2+1+9+2+6 = 25, and 2+5 = 7. Voldemort, or rather Tom Riddle, is therefore born one day placed under the sign of the 7!
  • Harry also hides the magic number within him, but in an even more subtle way. Let’s convert the letters of the first name into numbers, according to their position in the alphabet: HARRY is therefore written 8-1-18-18-25. The addition of these figures gives the result 70; and, you will have understood, 7+0 = 7!
  • The date of the great Battle of Hogwarts takes place on May 2, 1998: in addition to the simple addition of the day (May 2 = 02/05 = 2 + 5 = 7), we also obtain the number 7 by adding all the numbers of the date (2+5+1+9+9+8 = 34 and 3+4 =7).
  • There are 142 stairs at Hogwarts: a number at first glance chosen at random, but which actually hides the 7 (1+4+2 = 7).
  • Route 9 3/4 is indeed the most magical: 9+3+4 = 16, and 1+6 = 7!
  • The numbers 3, 4 and 9 appear two other times in the story: first, 1 Galleon is equivalent to 17 Mornilles (figurative appearance) and 493 (and therefore 7!) Noises. Then, in the mouth of Professor Snape and his famous page… 394!
  • Harry has a vision of Sirius being tortured by Voldemort in aisle 97 of the Department of Mysteries. We give it to you in thousand: 9 +7 = 16 and 1 + 6 = 7).

This is undoubtedly a non-exhaustive list, as the figures remain a science to be deciphered.

The 7 at the heart of history

The seven-volume saga has an incalculable and dizzying number of appearances of this figure.


As we’ve seen, Harry is linked to the magic number, whether by his month of birth, the size of his wand or even his first name. However, other connections can be made with the 7. First, a little-known occurrence: Harry’s Chocolate Frog card gives seven reasons for his fame. Then, a much more discreet but very symbolic reference: in The Deathly Hallows, we learn that Harry writes the letter “g” in the same way as his mother. The letter “g” is, as you will have understood, the seventh letter of the alphabet. A magical and moving nod to the hero’s mother.

Finally, one last reference, which may seem far-fetched, concerns Harry’s scar in the movies. We can indeed distinguish two connected 7s, one upright, the other upside down, and both written horizontally in mirror.

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Can you see the two 7s in Harry’s scar?


The school of witchcraft is full of winks and references to the number 7. The most obvious obviously concerns the seven years of schooling spent in the castle. We can also cite the common core of education, which includes seven subjects: astronomy, botany, defense against the forces of evil (which has known seven different teachers throughout history), history of magic, metamorphosis, potions and spells. Speaking of spells, did you know that there are seven types of spells? Here they are (translation into French is not always possible, the terms in English are given):

  • “transfiguration” (metamorphosis)
  • “charm” (enchantment of an object)
  • “jinx” (black magic with minor, not serious consequences)
  • “hex” (black magic with long-lasting effects and high consequences)
  • “curse” (worst form of black magic, with serious effects and consequences)
  • “counter-spell” (blocking a spell)
  • “healing spell” (healing a wounded or sick target)

Still in the spirit of schooling, let’s remember that dear Professor Lockart, and the seven books he prescribed for Harry and his classmates during the second year. Harry precisely who, with Ron, obtained seven OWLs at the end of his fifth year.

The architecture of Hogwarts also reveals secrets. In addition to the magic number hidden in the number of stairs, we can mention the seven floors of the school, as well as the seven secret passages that allow you to enter and leave the castle. Let’s not forget the Gryffindor common room, the central place of Harry’s adventures, which is located on the seventh floor of the castle.

The importance of the number 7 in Harry Potter
Hogwarts and its many stairs

Finally, seven ghosts and quoted spirits inhabit the castle: Nearly Headless Nick, the Bloody Baron, the Gray Lady, the Fat Monk, Mimi Whining, Professor Binns and Peeves.


The magic sport also contains more or less visible occurrences of the number 7. First, the most obvious: each Quidditch team has seven members. In the movies, Harry wears jersey number 7. This brings luck to his team: thanks to him, Gryffindor wins the Quidditch Cup for the first time in seven years. Finally, Harry proves that he is indeed “magical” at Quidditch since, throughout his matches, he has caught the Snitch… seven times!

The importance of the number 7 in Harry Potter
Harry catching his first Snitch

Families and groups of wizards

Of course, when we talk about the 7 and a family of wizards, we immediately think of the seven Weasley children. But did you know that this number is also associated with Ginny, who is the first Weasley daughter for seven generations?

In the Black family too, the magic number makes a few appearances. The family thus has seven disowned Blacks, and the tapestry has been in the house for seven centuries.

Without necessarily representing families, certain groups of characters who appear in the story have seven members: there are thus seven people petrified by the Basilisk, seven people in the Screaming Shack when Sirius is revealed, seven prisoners in the mansion of Malfoy at the end of the seventh film or, of course, seven Potters at the beginning of the Deathly Hallows.

Black magic and the forces of evil

From the first volume, the 7 finds himself twice on the path that leads Harry to Voldemort. First, there are seven steps to finding the Philosopher’s Stone:

  • bushy
  • the Devil’s Net
  • the flying keys
  • failures
  • the mountain troll
  • potions
  • the mirror of Erised

Then there are seven potions to be decided during Snape’s trial.

In the third volume of the saga, we learn that the Wolfsbane potion must be drunk seven days before the full moon. It is in this volume that we discover the existence of the Animagi: if their total number is undetermined, there are however seven of them which were listed by the Ministry in the 20th century.

During the Goblet of Fire, we are witnessing the Triwizard Tournament, which takes place in 1994, seven centuries after its previous edition. Moody Crazy Eye (aka Barty Croupton Jr)’s lock has seven locks.

In the sixth book, Bellatrix tests Snape’s loyalty by asking him seven questions.

Finally, there are obviously many times the magic number is linked to Voldemort:

  • Voldemort creates seven Horcruxes, which will be destroyed by seven different people
  • Voldemort and Harry cross paths seven times
  • Harry sees seven memories of Voldemort in the Pensieve

And so many others!

Many other references to the 7 can be found in the saga. Jumble: the Polyjuice has seven ingredients; the Weasley twins’ canary creams cost seven Sickles each; there are seven departments in the Ministry of Magic, as well as seven rooms in the Department of Mysteries…

As we have seen, the number 7 is therefore extremely present in the saga. Both a simple number with no real function and a number with primordial value, it is inseparable from the work.

There are undoubtedly other appearances of the magic number, do not hesitate to share them with us!

Sources: mugglenet, Harry Potter Wiki

Cover illustration by Alendyl for The Daily Prophet

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The importance of the number 7 in Harry Potter

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