503 (disambiguation)

503 may refer to:


 * 503 (number)
 * 503, a year
 * 503, a track by Hans Zimmer on the Angels & Demons soundtrack
 * 503 Service Unavailable, an HTTP status code
 * Area code 503, a North American telephone area code in northwestern Oregon
 * BMW 503, a grand tourer
 * Fiat 503, a small family car
 * Country code +503, for El Salvador
 * FN 503, a semi-automatic pistol manufactured by FN Herstal
 * A type of jeans, commonly in Levi's and Edwin
 * A type of steel used for making bicycle frames