This question brought up a good point about un-mixing via Accio. However, were there any rules set about the size of an object that can be summoned via that charm? Could something on the cellular or molecular level be summoned? From the books the smallest thing I can think of would be hair that was used to disguise Harry at the wedding; also in The Goblet of Fire, a fly was summoned as well.

  • book 4 harry was trying to summon everything he could in prep for the first event in the tri wizard tournament
    – Himarm
    Feb 10, 2016 at 22:48
  • 5
    Isn't this question a sub-query of this older question?
    – Rand al'Thor
    Feb 11, 2016 at 0:04
  • 3
    @randal'thor This question doesn't seem to be answered in that one, though. Feb 11, 2016 at 1:43
  • While the questions are related, I don't see them being dupes as the linked question mentions nothing on size.
    – Skooba
    Feb 11, 2016 at 14:53
  • 1
    I’m inclined to reopen this – although DVK’s question is a very thorough explanation of the summoning charm, I don’t see anything discussing size in those answers.
    – alexwlchan
    Feb 11, 2016 at 19:24

1 Answer 1


In my opinion, some spells require a variety of actions that will enable it to work. It usually falls under (or a combination of):

  1. Magical ability
  2. Movement/Aim of wand
  3. Focus/Concentration/Willpower
  4. Saying the incantation

In the case of Accio, it requires not only magical ability, but also Focus/Concentration/Willpower, and saying the incantation. In some cases aiming at the target also works to narrow down targeting of the spell and make it easier (aiming at the beaded bag to pull out tent from Deathly Hallows).

"Concentrate, Harry, concentrate. . . ." "What d'you think I'm trying to do?" said Harry angrily. "A great big dragon keeps popping up in my head for some reason...Okay, try again. . . ." - GoF

Now because a big scary dragon kept popping up in his mind and disrupting his spell, I would be assuming he is picturing and focussing on the broom (much like you have to picture your destination when apparating). Therefore, Harry would have to visualise a molecule or atom, or something on a cellular level. As it would be difficult to remember exactly what an atom looks like for a wizard (and considering at best they won't study science post age 11), I doubt it would be possible to summon anything on a molecular level.

Furthermore, the boy in the village would probably have been in Freds line of sight, meaning it would be easier to picture and concentrate and aim as he could look at the boy to see what he wants, instead of focussing on it when he couldn't see it.

Also, it seems Accio seems to work on a 1 to 1 basis, meaning saying Accio hairstrand would bring one hairstrand and not all the strands of hair. (In GoF, Molly continuously said Accio to summon the Ton Tongue Toffees, picturing them as opposed to saying the actual name of the item she was summoning). So if you were to say "Accio Mitochondria", it would bring only 1 mitochondria, which would be invisible to the naked eye anyway, and show no sign of change on the plant, making it seem like nothing happened. Perhaps a Priori Incantatem would show otherwise.

  • Molly was also furious when summoning the Ton Tongue Toffees, meaning her spells would have been more effective, more focus and willpower. Let's not forget under anger, she became a powerful enough witch to kill Bellatrix Lestrange. Feb 15, 2016 at 15:19
  • 5
    “So if you were to say "Accio Mitochondria", it would bring only 1 mitochondria” — Depends on how good you are at Greek, I guess. If I said “Accio mitochondria”, I would definitely expect it to summon multiple mitochondria, because mitochondria is the plural form. If I wanted just one, I’d say “Accio mitochondrion”. Feb 15, 2016 at 15:48
  • 2
    @JanusBahsJacquet Greek to me is what Maths is to JK :) Feb 15, 2016 at 16:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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