"How Long" is a song by Swedish singer-songwriter Tove Lo, released on 26 January 2022 as the lead single from her fifth studio album Dirt Femme. It also appears on the second season soundtrack of the HBO series Euphoria. The song was produced by A Strut and TimFromTheHouse. The music video was released on 10 February 2022 and directed by Kenten.
After the release of her fourth studio album, Sunshine Kitty (2019), Interscope Records released "How Long" on 26 January 2022 as the second single of Euphoria season 2 soundtrack, following Lana Del Rey's "Watercolor Eyes". According to Lo, its theme is about "love, betrayal and denial". She made the song during quarantine, and honored the track since it was featured in Euphoria, stating: "I'm so honored that it gets to be a part of Euphoria, a show I love so much because of its rawness and provocative storytelling."
An electro-pop song, "How Long" opens with a "propulsive nu-disco beat" and "glitchy sounds of synths", beginning at a slow tempo before gradually accelerating. It addresses the "agony" of a "one-sided affairs", according to Nylons Steffanne Wang. As the track settles into its rhythm, minimal drums enter alongside Lo's vocals. The "dark but chill sound" of synths and sparse percussion build tension toward a larger, melodic chorus, in which she asks, "how long have you loved another, while I'm dreaming of us together?"
Lo revealed the music video of "How Long" on 10 February 2022, directed by Kenten. Emily Zemler of Rolling Stone observed that the video "features the singer in a shimmering gold dress and boots â capturing the essence of vintage Hollywood glamour â while she moves robotically as tears stream down her face."
MTV described "How Long" as "ecstasy to the ears".