Heats
dimanche 12 août 2018, 03h00 GMT – 03h00 GMT
| Nom | Équipe | Temps | |
|---|---|---|---|
| 1 |  Regan Smith | United States | 2′ 7.86″ |
| 2 |  Taylor Ruck | Canada | + 0.51″ |
| 3 |  Kathleen Baker | United States | + 0.52″ |
| 4 | Kylie Masse | Canada | + 0.59″ |
| 5 |  Emily Seebohm | Australia | + 1.4″ |
| 6 | Olivia Smoliga | United States | + 1.41″ |
| 6 | Kaylee McKeown | Australia | + 1.41″ |
| 8 |  Natsumi Sakai | Japan | + 1.62″ |
| 9 | Hali Flickinger | United States | + 1.77″ |
| 10 | Ali Galyer | New Zealand | + 2.25″ |
| 11 | Anna Konishi | Japan | + 2.38″ |
| 12 | Mabel Zavaros | Canada | + 4.34″ |
| 13 | Kennedy Goss | Canada | + 4.79″ |
| 14 | Rio Shirai | Japan | + 5.19″ |
| 15 | Mikkayla Sheridan | Australia | + 5.47″ |
| 16 | Erika Seltenreich-Hodgson | Canada | + 6.58″ |
| 17 | Yifan Yang | China | + 6.73″ |
| 18 | Chloe Isleta | Philippines | + 11.67″ |
| 19 | McKenna DeBever | Peru | + 14.52″ |
| 20 | Gianna Vivien Garcia | Philippines | + 24.3″ |
| 21 | Osisang Chilton | Palau | + 38.9″ |