Shrinking Charm

• Incantation: Reducio
• Pronunciation: re-DOO-see-oh
• Wand Movement: Unknown
• Light: Unknown in the novels; depicted as purple in the film adaptation. (film)
• Effect: Causes the targeted object or creature to decrease in size. It is the direct counter-charm to the Engorgement Charm.
• Type: Charm

The Shrinking Charm is a fundamental piece of magic taught at Hogwarts School of Witchcraft and Wizardry. Its primary function is to reduce the physical size of objects and living creatures.

• In Harry Potter's second year, the charm's utility as an antidote was noted by Professor Severus Snape. When a Swelling Solution brewed by Harry malfunctioned and splashed him, Snape mentioned that a Shrinking Charm would be the correct remedy. Hermione Granger offered to perform it, but Snape handled the situation himself.
• During their third year, students in Professor Remus Lupin's Defence Against the Dark Arts class practiced the Shrinking Charm. Neville Longbottom memorably used the charm to successfully shrink a Boggart that had taken the form of Professor Snape.
• The incantation Reducio was first stated in the fourth book when Barty Crouch Jr., disguised as Alastor Moody, used it to shrink a large spider he had just used to demonstrate the Unforgivable Curses.
• In his fifth year, Harry Potter taught the Shrinking Charm to members of Dumbledore's Army in the Room of Requirement as part of their practical defensive training.

The Shrinking Charm is part of the standard curriculum for second-year students at Hogwarts. It is generally considered a basic and manageable spell, as even students who often struggle with practical magic, like Neville Longbottom, were able to master it with practice. The direct counter-spell is the Engorgement Charm, which has the opposite effect. Its incantation, Engorgio, causes an object or creature to swell in size. The two charms work in tandem, allowing a witch or wizard to precisely control an object's dimensions.

The incantation Reducio is derived from the Latin verb reducere, which translates to “to lead back,” “to diminish,” or “to reduce.” The name of the incantation is a direct and literal description of the spell's magical effect.

• In the film adaptation of Harry Potter and the Goblet of Fire, the spell, when cast by Barty Crouch Jr. as Moody, emits a jet of purple light that envelops the spider, causing it to rapidly shrink. (film)
• The Shrinking Charm appears in several Harry Potter video games, often as a utility spell that allows the player to shrink environmental obstacles to solve puzzles or clear a path. (video game)