Formula 17 (Chinese: 17歲的天空; pinyin: Shíqī Suì de Tiānkōng) is a 2004 Taiwanese film directed by Chen Yinjung.

The film describes Tien's experiences with his loyal roommate and his friends, and a surprising relationship that he develops with the local "Playboy".

Naïve country bumpkin Chou Tien Tsai (Tony Yang) goes to Taipei to meet an internet friend face-to-face.

Tien, hurt and unknowing of the entire story behind Bai's intimacy issues, leaves a message saying that 'this kind of misunderstanding won't happen again'.

A lifetime of self-fulfilling this prophecy is what led Bai to become a serial one-night stander and lose his ability to love.

The ending credits include a short segment on Yu, CC, and Alan and their somewhat stereotyped views upon gay fashion.