2025 in Review: Which Events Produced Biggest Percentage Gap Between World Leader and No. 2
The year-end rankings for 2025 featured Canadian sensation Summer McIntosh on top of four events, with American star Gretchen Walsh leading the way in three disciplines. But the women didn’t just headline in multiple events. Rather, McIntosh and Walsh also were the most dominant in specific events, evident in the percentage gap between their world-leading performances and what the No. 2 performer managed.
In the 50 butterfly and 100 butterfly, Walsh was more than 2% faster than her closest competitors. But it was McIntosh who enjoyed the biggest separation over a rival. Thanks to her world-record time of 4:23.65 in the 400 individual medley, McIntosh was nearly 10 seconds faster than Japan’s Mio Narita (4:33.26), the second-ranked athlete in the event. The difference between those marks was a striking 3.57%, easily the biggest difference in any event.
The list below indicates the percentage gap between the top time in the world and the No. 2 global effort in the 17 individual events contest at the international level.
Here is the complete list of percentage differences between No. 1 and No. 2:
50 Freestyle
World Leader: Gretchen Walsh (United States) – 23.91
No. 2 Mark: Torri Huske (United States) – 23.98
Percentage Difference: .29%
100 Freestyle
World Leader: Torri Huske (United States) – 52.43
No. 2 Mark: Marrit Steenbergen (Netherlands) – 52.55
Percentage Difference: .22%
200 Freestyle
World Leader: Mollie O’Callaghan (Australia) – 1:53.48
No. 2 Mark: Li Bingjie (China) – 1:54.52
Percentage Difference: .91%
400 Freestyle
World Leader: Summer McIntosh (Canada) – 3:54.18
No. 2 Mark: Katie Ledecky (United States) – 3:56.81
Percentage Difference: 1.11%
800 Freestyle
World Leader: Katie Ledecky (United States) – 8:04.12
No. 2 Mark: Summer McIntosh (Canada) – 8:05.07
Percentage Difference: .19%
1500 Freestyle
World Leader: Katie Ledecky (United States) – 15:24.51
No. 2 Mark: Simona Quadarella (Italy) – 15:31.79
Percentage Difference: .78%
50 Backstroke
World Leader: Katharine Berkoff (United States) – 26.97
No. 2 Mark: Kaylee McKeown (Australia) – 27.06
Percentage Difference: .33%
100 Backstroke
World Leader: Kaylee McKeown (Australia) – 57.16
No. 2 Mark: Regan Smith (United States) – 57.35
Percentage Difference: .33%
200 Backstroke
World Leader: Kaylee McKeown (Australia) – 2:03.33
No. 2 Mark: Regan Smith (United States) – 2:04.29
Percentage Difference: .77%
50 Breaststroke
World Leader: Ruta Meilutyte (Lithuania) – 29.54
No. 2 Mark: Eneli Jefimova (Estonia) – 29.83
Percentage Difference: .97%
100 Breaststroke
World Leader: Anna Elendt (Germany) – 1:05.19
No. 2 Mark: Kate Douglass (United States) – 1:05.27
Percentage Difference: .12%
200 Breaststroke
World Leader: Kate Douglass (United States) – 2:18.50
No. 2 Mark: Evgeniia Chikunova (Russia) – 2:19.96
Percentage Difference: 1.04%
50 Butterfly
World Leader: Gretchen Walsh (United States) – 24.66
No. 2 Mark: Alexandria Perkins (Australia) – 25.31
Percentage Difference: 2.60%
100 Butterfly
World Leader: Gretchen Walsh (United States) – 54.60
No. 2 Mark: Roos Vanotterdijk (Belgium) – 55.84
Percentage Difference: 2.24%
200 Butterfly
World Leader: Summer McIntosh (Canada) – 2:01.99
No. 2 Mark: Regan Smith (United States) – 2:04.99
Percentage Difference: 2.42%
200 Individual Medley
World Leader: Summer McIntosh (Canada) – 2:05.70
No. 2 Mark: Yu Zidi (China) – 2:07.41
Percentage Difference: 1.35%
400 Individual Medley
World Leader: Summer McIntosh (Canada) – 4:23.65
No. 2 Mark: Mio Narita (Japan) – 4:33.26
Percentage Difference: 3.57%