World U-23 bests in the sport of athletics are the all-time best marks set in competition by aged 22 or younger throughout the entire calendar year of the performance. Technically, in all under-23 age divisions, the age is calculated "on December 31 of the year of competition" to avoid age group switching during a competitive season. World Athletics doesn't maintain an official list for such performances. All bests shown on this list are tracked by statisticians not officially sanctioned by the governing body.