The world of Sword Art Online places its characters in a gaming realm that isn't just something played on a screen, but rather in a virtual world where the players can actually live. Unfortunately, it's also a world where someone can become trapped, a fate that befell an unlucky 10,000 people.
Because SAO takes place over several years, it can be hard to keep track of how old the protagonists are supposed to be. To make things even more confusing, some characters aren't entirely human, but rather collections of sentient data. However, some characters do have official canon ages confirmed by Reki Kawahara in either the show or the light novel source material.
10 Suguha Kirigaya / Leafa
15 - 17
Kirigaya Suguha, also known by the aliases "Leafa" and "Terraria," is a recurring character throughout Sword Art Online, taking a prominent role in various arcs and spin-offs. She's Kazuto's cousin and became a kendo practitioner to appease their grandfather when Kazuto left the field.
Suguha learned about online games while Kirito was trapped within SAO, leading to her trying out Alfheim Online. Though she was 15 during the Fairy Dance Arc, she still played a large role in helping Kirito find a way to break Asuna out of her cage. She appears later during the Phantom Bullet Arc at 16, and by the time of the Unital Ring arc, she's 17 years old, balancing her life in VR with being a high school student.
9 Shino Asada / Sinon
16 - 17
Asada Shino, also known as "Sinon" within Gun Gale Online and "Solus the Sun Goddess" within Project Alicization, is one of the more prominent Sword Art Online characters who appears post-Aincrad.
Shino starts out playing Gun Gale Online to get over her personal problems dealing with guns. It clearly works, given she becomes a top-tier sniper within GGO, even becoming a top contender in the Bullet of Bullets Competition. She is 16 during the Phantom Bullet Arc and the Alicization Arc, where she dives in to help out Kirito. During the Unital Ring Arc, she is 17 years old.
8 Yuuki Konno / Yuuki
15
Konno Yuuki, also known as Yuuki, takes a prominent role in the series' side stories like Mother's Rosario. She is one of the founders and leaders of the "Sleeping Knights" guild, known as the Absolute Sword thanks to how many duels she won.
Once terminally ill, Konno joined forces with other players in a similar position who used the gameplay as a form of informal sedative care. She was 15 at the time of her death, having been born in 2010 and eventually passing away in 2026.
7 Eugeo
11 - 19
Eugeo is a prominent character during the start of the Alicization Arc. Born in a remote village of the Underworld's human empire, he was tasked with taking on a giant tree, the Gigas Cedar, with Kirito. However, when his childhood friend, Alice Zuberg, was apprehended by a knight, he eventually devoted himself to rescuing her, becoming a knight, and proving himself able to use the Blue Rose Sword.
Eugeo appears at different ages throughout the series. He is 11 during a prologue and 17 during the first chapter of the arc. He is 19 throughout most of his later appearances, and at the time of his death at the hands of Quinella.
6 Alice Zuberg
11 - 19
Though she's not a part of the original Sword Art Online anime, Alice Zuberg becomes a prominent character during the Alicization Arc. The daughter of a village chief, she was a childhood friend of Eugeo and Kirito. Though the three of them were inseparable, after they broke a taboo of the land, Alice was taken away from them and forced to become an Integrity Knight.
As an Integrity Knight, she was stripped of her memories and became known through the alias, "Alice Synthesis Thirty," the 30th Humanoid Knight assigned to protect the world. Like Eugeo, she was 11 during the prologue of the arc, 17 during its first chapter, and 19 when she appears in a later chapter.
5 Ryotaro Tsuboi / Klein
22 - 25
Tsuboi Ryotaro, also known as Klein, is a recurring character in Sword Art Online who featured prominently in the Aincrad Arc. Though he initially considered himself lucky to be able to purchase Sword Art Online, Klein became one of the 10,000 characters trapped in the virtual reality world.
Though he eventually became a guild leader, Klein started as a rookie just like everyone else. However, realizing Kirito knew how the game worked, Klein understood Kirito was a beta tester and reached out to him to learn the basics of how the game worked. At the start of the Aincrad Arc, Klein was 22 years old, and aged to 24 by the end of their two years inside the game. Klein got back into VRMMOs with the Phantom Bullet Arc, where he was 25 years old.
4 Andrew Gilbert Mills / Agil
27 - 30
Andrew Gilbert Mills, also known as Agil, is a recurring character throughout SAO, taking a prominent role during the Aincrad Arc. He was one of the 10,000 players trapped within the virtual reality world, where he was an ax-wielder and a merchant, running a shop and helping lower level players where he could. Eventually, he manages to re-enter the real world to help his wife run their business, the Dicey Cafe, again.
In a tentative character ages list from series creator Reki Kawahara, Mills was supposedly born March 9th, 1995. That means at the start of the Aincrad Arc, he's already 27 years old. By the end and when he starts playing Alfheim Online, he's 29 years old. By the time of the Phantom Bullet arc, he's 30 years old, making him one of the oldest in the supporting cast.
3 Keiko Ayano / Silica
12 - 15
Ayano Keiko, also known as Silica, takes a prominent role during the Aincrad arc and some of the series' spin-offs, becoming a recurring character throughout the series. She was one of the 10,000 players trapped within the virtual reality world and was seen as both a Beast Tamer and a Cait Sith.
Unlike many of Kirito's other friends, Silica was never one of the strongest characters, and even by the end of the game she was still a few dozen levels below max level. Some of this is down to her age though, as she was only 12 at the start of the Aincrad arc. By the beginning of the Fairy Dance Arc, she was 14, and by the Phantom Bullet storyline she was 15.
2 Asuna Yuuki / Asuna
15 - 19
Asuna Yuuki, also known as just Asuna and temporarily as Stacia, is the main heroine of Sword Art Online, going from a protagonist to a deuteragonist. The SAO Progressive movies revealed that Asuna wasn't a video game expert, but was one of the many people unfortunate enough to get trapped in Sword Art Online when the game went live.
Surprisingly, Asuna is a year older than Kirito when the Aincrad Arc begins, meaning she starts at 15 years old. After two years of struggling in Aincrad, she's 17 when she's pulled into the world of Alfheim Online by Sugou Nobuyuki, the man Asuna's father arranged for her to marry. By the Uintal Ring storyline following the Alicization Arc, Asuna is nineteen years old.
1 Kazuto Kirigaya / Kirito
14 - 17
Kirigaya Kazuto, also known as Narusaka Kazuto or Kirito online, is the protagonist of the main series of Sword Art Online. Orphaned at a young age and adopted by his aunt, Kazuto grew up to become a prominent hacker and one of the most powerful isekai anime characters. In the multiple Virtual Reality MMOs he'd master, he'd develop many names based on his feats, from the Black Swordsman to the Star King.
At the start of SAO's Aincrad Arc, Kazuto is just 14 years old when he gets trapped in Sword Art Online. By the time it ends and he travels into the world of Alfheim Online to rescue Asuna, he's 16 years old. When he's trapped within the world of Project Alicization while his mind recovers, he's 17 years old.