Characters | Height | Age | Gender |
Kid | ~ 4 ft 4 in | 9 years old | Male |
Jo | ~ 5 ft 7 in | 16 years old | Female |
Rosa | 40 ft / ~ 3 ft 2 in | 4 years old | Female |
ANALYSIS OF KID COSMIC CHARACTERS’ HEIGHTS

According to Rosa’s Fandom Wiki profile, she is 40 feet tall. This is her published height because she was given the power to be a giant.
However, Rosa is about 3 feet and 2 inches in height based on her age in normal circumstances. As stated by CDC, children her age has this average height.
We also compared the heights of the characters based on how they stand beside each other on the show pictures and the average size of children their age.
With this information, we estimated Kid to be about 4 feet and 4 inches in height based on the average height of four-year-olds, per CDC.
Lastly, we have Jo, who is a teenager. According to Healthline, girls her age are about 5 feet and 3 inches in height. However, seeing Kid standing beside Rosa, Rosa is more than a foot taller than Kid. So, we estimated her height to be at least 5 feet and 7 inches, making her above average in height.
RELATED: Go, Dog. Go! Characters: Heights and Ages
ANALYSIS OF KID COSMIC CHARACTERS’ AGES

According to Kid Cosmic Fandom Wiki, Jo is between 16 to 18 years old.
Then, from the same source, Rosa is only four years old while Kid is nine years old.
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Reference:
https://kidcosmic.fandom.com/wiki/Kid_Cosmic_Wiki
https://kidcosmic.fandom.com/wiki/Jo
https://hero.fandom.com/wiki/Rosa_(Kid_Cosmic)
https://kidcosmic.fandom.com/wiki/Kid
https://www.imdb.com/title/tt9248538/
https://www.netflix.com/title/80244340
https://www.healthline.com/health/when-do-girls-stop-growing
https://www.disabled-world.com/calculators-charts/height-weight-teens.php