40

40 or forty commonly refers to:
 * 40 (number)
 * The years 40 BC and AD 40

40 or forty may also refer to:

Music

 * 40 (record producer) (born 1983), Canadian hip hop producer (born Noah Shebib)
 * Forty (album), a 2001 live album by Thomas Dolby
 * 40 (Foreigner album), 2017
 * 40 (Stray Cats album), 2019
 * 40 (Sunnyboys album), 2019
 * 40 (Grupo Niche album), 2020
 * 40, an album by Peter Morén
 * 40 (concert video), by the Allman Brothers Band
 * "40" (song), by U2
 * "40'", a song by Franz Ferdinand from Franz Ferdinand, 2004
 * "Forty", a song by Karma to Burn from Almost Heathen, 2001

Films

 * This Is 40, a 2012 American film

Other uses

 * 40 ounce or forty, a bottle of malt liquor
 * Forty winks or forty, sleep or nap
 * .40 S&W, pistol cartridge
 * .40 Super, wildcat pistol cartridge
 * (, the ASCII character with code 40
 * 40 Harmonia, a main-belt asteroid