Men's ====
Flyweight==== • 1904: up to 105 lb (47.6 kg) • 1920–1936: up to 112 lb (50.8 kg) • 1948–1964: up to 51 kg • 1968–2008: 48–51 kg • 2012–2020: 49–52 kg • 2024–present: –51 kg ;Notes ====
Featherweight==== • 1904: 115–125 lb (52.2–56.7 kg) • 1908: 116–126 lb (52.6–57.2 kg) • 1920–1928: 118–126 lb (53.5–57.2 kg) • 1932–1936: 119–126 lb (54.0–57.2 kg) • 1948: 54–58 kg • 1952–2008: 54–57 kg • 2020–present: 52–57 kg ====
Lightweight==== • 1904: 125–135 lb (56.7–61.2 kg) • 1908: 126–140 lb (57.2–63.5 kg) • 1920–1936: 126–135 lb (57.2–61.2 kg) • 1948: 58–62 kg • 1952–2008: 57–60 kg • 2012–2020: 56–60 kg • 2024–present: 58–63.5 kg ====
Welterweight==== • 1904: 135–145 lb (61.2–65.8 kg) • 1920–1936: 135–147 lb (61.2–66.7 kg) • 1948: 62–67 kg • 1952–2000: 63.5–67 kg • 2004–2020: 64–69 kg • 2024–present: 64–71 kg ====
Middleweight==== • 1904: 145–158 lb (65.8–71.7 kg) • 1908: 140–158 lb (63.5–71.7 kg) • 1920–1936: 147–160 lb (66.7–72.6 kg) • 1948: 67–73 kg • 1952–2000: 71–75 kg • 2004–2020: 69–75 kg • 2024–present: 72–80 kg ====
Heavyweight==== • 1904–1908: over 158 lb (71.7 kg) • 1920–1936: over 175 lb (79.4 kg) • 1948: over 80 kg • 1952–1980: over 81 kg • 1984–present: 81–92 kg ====
Super heavyweight==== • 1984–2020: over 91 kg • 2024–present: over 92 kg
Women's Flyweight Bantamweight Featherweight Lightweight Welterweight Middleweight ==Discontinued events==