Erasmus helped popularize “Pandora’s box” by translating the Greek jar as a box.
Hesiod’s original container is generally identified as a pithos, a large storage jar. The English expression “Pandora’s box” reflects a later translation tradition rather than the exact object described in the earliest Greek account. Renaissance humanist Erasmus of Rotterdam is widely credited with helping establish the box wording through his Latin treatment of the story.
The shift was linguistically influential. A box sounds like a portable, closed container designed to hold a secret, while a pithos was a large earthenware vessel used for storage. As the phrase spread through European languages, visual artists and writers increasingly imagined a chest or box instead of a jar.
Ovid also wrote about Pandora-related material in Latin, but he is not the best answer to this specific translation question. The widespread modern phrase is therefore partly the result of Renaissance reception, not a direct description from Hesiod’s Greek text.