| Event: | Women's 400 metre freestyle |
| Games: | 1928 Summer |
| Venue: | Olympic Sports Park Swim Stadium |
| Date: | 4–6 August |
| Competitors: | 20 |
| Nations: | 9 |
| Gold: | Martha Norelius |
| Goldnoc: | USA |
| Silver: | Marie Braun |
| Silvernoc: | NED |
| Bronze: | Josephine McKim |
| Bronzenoc: | USA |
| Prev: | 1924 |
| Next: | 1932 |
The women's 400 metre freestyle was a swimming event held as part of the swimming at the 1928 Summer Olympics programme.[1] It was the second appearance of the event, which was established in 1924 after 1920 a 300-metre event was held. The competition was held from Saturday to Monday, 4 to 6 August 1928.
Twenty swimmers from nine nations competed. The winning margin was an astonishing 15 seconds which as of 2023 is the only time this event has been won by more than 8 seconds at the Olympics.
These were the standing world and Olympic records (in minutes) prior to the 1928 Summer Olympics.
| World Record | 5:49.6 |  Martha Norelius | New York City (USA) | 30 June 1928 | |
|---|---|---|---|---|---|
| Olympic Record | 6:02.2 | Martha Norelius | Paris (FRA) | 15 July 1924 |
In the first heat Martha Norelius set a new world record with 5:45.4 minutes. In the final she bettered her own record to 5:42.8 minutes.
Saturday 4 August 1928: The fastest two in each heat and the fastest third-placed from across the heats advanced.
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 1 | 5:45.4 | , | |||
| 2 | 6:12.3 | ||||
| 3 | 6:26.4 | ||||
| 4 | Unknown | ||||
| 5 | Unknown | ||||
| 6 | 6:37.0 |
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 1 | 6:04.6 | ||||
| 2 | 6:11.0 | ||||
| 3 | 6:12.0 | ||||
| 4 | 6:28.0 | ||||
| 5 | Unknown | ||||
| 6 | Unknown |
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 1 | 6:10.0 | ||||
| 2 | 6:16.8 | ||||
| 3 | 6:20.0 | ||||
| 4 | Unknown |
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 1 | 5:53.8 | ||||
| 2 | 6:03.6 | ||||
| 3 | 6:10.4 | ||||
| 4 | Unknown |
Sunday 5 August 1928: The fastest three in each semi-final advanced to the final.
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 1 | 5:58.0 | ||||
| 2 | 6:01.6 | ||||
| 3 | 6:06.4 | ||||
| 4 | Unknown | ||||
| 5 | Unknown |
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 1 | 5:54.6 | ||||
| 2 | 5:55.0 | ||||
| 3 | 6:09.0 | ||||
| 4 | Unknown |
Monday 6 August 1928:
| Rank | Swimmer | Nation | Time | Notes | |
|---|---|---|---|---|---|
| 5:42.8 | |||||
| 5:57.8 | |||||
| 6:00.2 | |||||
| 4 | 6:07.0 | ||||
| 5 | 6:07.2 | ||||
| 6 | 6:11.6 |