Swimming at the 2018 Summer Youth Olympics – Girls' 400 metre freestyle
The girls' 400 metre freestyle event at the 2018 Summer Youth Olympics took place on 12 October at the Natatorium in Buenos Aires, Argentina.Results
Heats
The heats were started at 10:52.
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 4 | 4 | Ajna Késely | | 4:10.74 | Q |
| 2 | 3 | 4 | Delfina Pignatiello | | 4:11.86 | Q |
| 3 | 4 | 5 | Marlene Kahler | | 4:13.10 | Q |
| 4 | 2 | 5 | Nicole Oliva | | 4:16.72 | Q |
| 5 | 3 | 2 | Duné Coetzee | | 4:16.73 | Q |
| 6 | 4 | 7 | Kaitlynn Sims | | 4:16.91 | Q |
| 7 | 4 | 1 | Delfina Dini | | 4:17.00 | Q |
| 8 | 3 | 8 | Andrea Galisteo | | 4:17.07 | Q |
| 9 | 4 | 8 | Erika Fairweather | | 4:17.43 | |
| 10 | 2 | 4 | Gan Ching Hwee | | 4:17.86 | |
| 11 | 3 | 3 | Celine Rieder | | 4:18.10 | |
| 12 | 3 | 6 | Rafaela Raurich | | 4:18.71 | |
| 13 | 3 | 5 | Petra Barócsai | | 4:18.95 | |
| 14 | 3 | 7 | Tinky Ho | | 4:19.49 | |
| 15 | 4 | 6 | Maddie Donohoe | | 4:19.54 | |
| 16 | 2 | 3 | Malene Rypestøl | | 4:21.28 | |
| 17 | 3 | 1 | Aleksandra Knop | | 4:22.09 | |
| 18 | 4 | 2 | Kate Beavon | | 4:22.48 | |
| 19 | 4 | 3 | Anja Crevar | | 4:22.89 | |
| 20 | 2 | 6 | Samantha Bello | | 4:23.27 | |
| 21 | 2 | 1 | Ieva Maļuka | | 4:24.64 | |
| 22 | 2 | 2 | Arianna Valloni | | 4:26.87 | |
| 23 | 2 | 7 | Alexandra Frazão | | 4:27.00 | |
| 24 | 1 | 4 | Sandy Atef | | 4:30.88 | |
| 25 | 1 | 5 | Natalia Kuipers | | 4:45.60 | |
| 26 | 1 | 3 | Katie Rock | | 4:50.72 | |
Final
The final was held at 19:13.
| Rank | Lane | Name | Nationality | Time | Notes |
| 4 | Ajna Késely | | 4:07.14 | |
| 5 | Delfina Pignatiello | | 4:10.40 | |
| 3 | Marlene Kahler | | 4:12.48 | |
| 4 | 2 | Duné Coetzee | | 4:15.27 | |
| 5 | 7 | Kaitlynn Sims | | 4:15.53 | |
| 6 | 6 | Nicole Oliva | | 4:16.61 | |
| 7 | 8 | Andrea Galisteo | | 4:16.91 | |
| 8 | 1 | Delfina Dini | | 4:19.25 | |
