Related fun fact: Spongebob is over 51 years old. At least he is during the events of the first move.

Lets look at the numbers. In the first scene of the movie, spongebob shows off his wall of 374 ***consecutive*** employee of the month awards. 374 months is 31 years and 2 months. So he’s been winning the award every month for over 31 years straight.

But he didnt start working there when he was 1 year old. In the very first episode, where he *gets* the job at the krusty krab, he’s living on his own already, owns his own home, and is clearly meant to be a legal adult. So he has to be at *least* 18 to start with. Yes he’s a sponge and some sponges live to be hundreds of years old, but the sea creatures of Bikini Bottom are clearly anthropomorphized and their ages all standardized to match human aging. This is further supported by the fact that Pearl is 16 and is in high school, Mr Krabs is in his 70’s and is considered to be an old man, there are various flashback episodes that shows characters at younger stated ages, and theyre in the grade youd expect them to be in at that point, etc. Anyway, Spongebob is AT LEAST 18 as of episode 1.

18 years + 31 years 2 months is 49 years, 2 months.

Theres another episode where Spongebob and Squidward compete to win the employee of the month award, where Spongebob says he’s won it 26 times in a row, but at the end of the episode, neither of them win it. That means that *this* streak of 26 consecutive wins is separate from the streak of 374 consecutive wins mentioned in the movie. In other words, he wins it 26 times in a row, then loses it for at least one month, then wins it another 374 times in a row. 26 times is 2 years, 2 months. Adding that to our previous total:

18 years + 31 years 2 months + 2 years 2 months = 51 years 4 months.

There are at least 2 other episodes where spongebob loses the employee of the month award, but we dont know how long of a streak he had going at those times, so we cant calculate them. What we CAN say for sure is that Spongebob is at ***least*** 51 and a third years old as of the events of the first movie.

Which is ironic, seeing as the entire movie is all about him being “just a kid.”