Yoda is one of the oldest characters in the Star Wars galaxy. Having lived through most of the Skywalker saga, Yoda also experienced the entirety of the earlier High Republic Era. Having lived to almost a full millennium, it's interesting to look at how old the Jedi Grandmaster was during the films and earlier periods of the galaxy far, far away.
Without a doubt, Yoda is one of the most iconic Star Wars characters of all time, having first appeared in 1980's Empire Strikes Back to help teach Luke Skywalker the path of the Jedi. However, Yoda's full history dates so much further beyond the events of the films, going beyond even the High Republic Era which began almost 500 years before the events of the prequels' Phantom Menace. While there is much about Yoda and his species that remains a mystery in the Star Wars canon, his exact age in the movies, shows, and beyond is something that can be determined for the diminutive yet extremely powerful Jedi Master.
Your browser does not support the video tag. When Did Yoda Become A Jedi? 
According to the official Star Wars Timelines reference guide, Yoda was born in the year 896 BBY (BBY standing for Before the Battle of Yavin as seen in A New Hope). The book also confirms that Yoda began training Jedi 100 years later in 796 BBY. As such, the future Grandmaster of the Jedi Order must have been initiated into the Jedi Order before this period.
Assuming the Jedi Order's traditional practices were in effect when it came to bringing Force-sensitive children to the Jedi Temple for training, it can be estimated that Yoda came to the Jedi Temple between the ages of 1-3 but before the age of 6. As such, Yoda was likely brought to the Temple around the year 893 BBY. While it's unknown when exactly Yoda achieved the rare rank of Jedi Grandmaster, it was a title he shared with Xo Lahru, Pra-Tre Veter, and Jedi Master Ry Ki-Sakka as early as 232 BBY during the High Republic Era.
How Old Is Yoda In Star Wars: The High Republic? 
With the High Republic having begun in the year 500 BBY, Master Yoda was 396 at the start of this new age of peace and prosperity when the relationship between the Republic and Jedi Order couldn't have been better. However, Lucasfilm's High Republic initiative is largely split into three Phases. Phase I began during the year 232 BBY with the rise of the Nihil marauders, The Great Hyperspace Disaster, as well as the dedication and subsequent destruction of Starlight Beacon. This is also the era where the animated Young Jedi Adventures show takes place. During this time, Yoda would be 664, around 200 years before the events of The Phantom Menace.
Phase II goes back even further to the year 380 BBY. In Phase II, the galaxy is still expanding into the Outer Rim while the Jedi face the cult known as the Path of the Open Hand along with the predators known as the Nameless, the same creatures the Nihil would later use to bring down Starlight Beacon. During this period, Yoda was 516 years old. Lastly, the recently kickstarted Phase III takes place a year after Phase I, meaning Yoda would be about 665 as the Jedi Order faces the aftermath of Starlight's fall and the growing threat of the Nihil.
