Summary
There has been speculation about Ash's age in the Pokémon anime, with fans estimating that he would be approximately 13-14 years old. This estimation is based on the number of episodes and the assumption that each episode represents a day.
Taking into account the occasional indications of time passing in the anime, such as the mention of a year since Ash and Pikachu met and the one-year construction of a magnet train, it can be inferred that Ash is at least 17 years old or older.
If Ash had aged realistically throughout the series, he would have reached adulthood by the time of the Aim to Be a Master miniseries. However, despite the progression of time in the anime, Ash's official age remains 10 years old.
Ash Ketchum, the main character of the Pokémon anime, is officially recognized as a 10-year-old throughout the series. This fact remains consistent from the early episodes in Kanto to the later episodes of his miniseries, Aim to Be a Master. However, if we were to consider the possibility of time progressing for Ash, how old would he be?
Unfortunately, there is no definitive answer to this question. However, there are various ways to estimate his age based on different clues provided in the anime. Some fans speculate that Ash is somehow prevented from aging in Pokémon, but if that were true, other characters would have surely mentioned it by now. In fact, the passage of time in Pokémon is more similar to that found in Western comics, where the storyline remains in a perpetual "modern-day" setting, even if significant events occurred in the past. Although time passes for characters behind the scenes, those in the spotlight remain unchanged.
Ash is 36 Years Old (if Pokémon Happened in Real Time)
Ash is Only 10 Years Old (in Pokemon's Official Timeline)
If Ash aged alongside the real world, he would be 36 years old in Pokémon. However, it is not reasonable to assume that time passes at the same rate as reality for Ash. To estimate his age, the simplest method would be to count the number of episodes. Since most episodes of Pokémon occur in a single day, considering 1 episode as 1 day, we can calculate that 1,232 days have passed from the beginning to the end of his journey. This equates to approximately 3 years and 137 days, placing Ash's age between 13 and 14 years old. Although this estimation seems reasonable, it is a rough approximation and does not account for episodes that span longer periods or story arcs that occur within the same day.
The passage of time in the anime is occasionally marked. For instance, prior to the release of the third movie, "Entei and the Spell of the Unown," a short film indicated that a year had passed since Ash and Pikachu met in Pallet Town (it is mentioned elsewhere that Ash began his journey on his 10th birthday). This movie was released between episodes 155 and 156 in Japan, which suggests that the events of those 155 episodes occurred over the course of a year, slower than the one-day-per-episode pace. Episode 158 unveils the construction of a magnet train in Johto, which is expected to take at least another year to complete. This train is later ridden in the final episodes of the Black and White era, indicating that at least one year has transpired during the intervening 640 episodes. Furthermore, various other episodes within this period hint at the passage of more than one year.
Ash's Companions Would Be Even Older
Some series appear to span a fixed period, like Sun and Moon, which essentially covered an entire school year. Additionally, there are instances such as Professor Burnett's baby being born since Ash left Alola, indicating that the first 36 episodes of Pokémon Journeys occur over a minimum of 9 months. Notably, certain major events, such as tournaments, are often mentioned to be approaching within a specific timeframe, thereby establishing a duration for the episodes in between. Considering these specific time references, it can be inferred that Ash should be at least 17 years old, if not older.
Similarly, Brock and Misty can also be analyzed with this same reasoning. Misty's age remains undisclosed in the dubbed version of Pokémon, but in the original Japanese version, she is also depicted as a 10-year-old, ensuring she is roughly the same age as Ash according to any of these standards. Upon his initial introduction, Brock is portrayed as slightly older, at the age of 15. Consequently, if we take into account the passage of time based on the rate of one episode per day, Brock would be in his 40s in reality, just over 18 years old by that metric, and at least 22 years old according to the time indications within the show. Interestingly, these estimations correspond quite well with Brock's aspirations towards the end of the series, as he is portrayed as training to become a Pokémon doctor, a pursuit more fitting for a young man in his 20s rather than a 15-year-old.
It's surprising, but Ash would almost be an adult by the time of Aim to Be a Master. However, these ideas only give us an estimate of how old he would be if he had aged correctly throughout the series. Despite officially being 10 years old, the Pokémon anime's 1,200+ episodes suggest that a significant amount of time has passed, and specific durations have even been mentioned at certain points. It's disappointing that Ash and the other heroes in the Pokémon anime didn't grow up alongside the viewers as they should have.