# Swimming at the 2012 Summer Olympics – Women's 100 metre butterfly

The women's 100 metre butterfly event at the 2012 Summer Olympics took place on 28–29 July at the London Aquatics Centre in London, United Kingdom.
U.S. swimmer Dana Vollmer demolished a new world record to clear a 56-second barrier and to claim the Olympic title in the event for the first time since Amy Van Dyken did so in 1996. She touched third at the initial length, but powered home with a back-half strategy on the final stretch to capture the gold in 55.98, the first sub-56 second time in the event's history, shaving 0.08 seconds off the previous record set by Sweden's Sarah Sjöström in a since-banned high-tech body suit from the 2009 World Championships. China's Lu Ying came from behind with the same tactic to grab a silver in 56.87, while Australia's Alicia Coutts nearly pulled from worst-to-podium effort after turning last at the 50-metre lap to put up a late resistant surge for the bronze in 56.94.
Sjostrom, the former world record holder, finished off the podium with a fourth-place time in 57.17, and was followed in fifth by Italy's Ilaria Bianchi at a lifetime best and national record of 57.27. Denmark's Jeanette Ottesen Gray paid for an aggressive strategy with an early lead on the first half, before fading to sixth in 57.35. Vollmer's teammate Claire Donahue (57.48) and Great Britain's Ellen Gandy (57.76) rounded out the field. For the first time in Olympic history, all eight finalists finished the race under a 58-second barrier.
Earlier in the prelims, Vollmer posted both a textile and an American best of 56.25 to lead all swimmers for the top seed, wiping out Inge de Bruijn's 2000 Olympic record by 36-hundredths of a second.
Notable swimmers missed the final roster including Singapore's Tao Li, who delivered a surprise fifth-place finish in Beijing four years earlier; Gandy's home teammate Francesca Halsall; Poland's four-time Olympian Otylia Jędrzejczak; Australia's defending bronze medalist Jessicah Schipper; and Netherlands' Inge Dekker, who later scratched the semifinals to focus on her 4×100 m freestyle relay duty.

## Records

Prior to this competition, the existing world and Olympic records were as follows.
| World record | Sarah Sjöström (SWE) | 56.06 | Rome, Italy | 27 July 2009 | |
| Olympic record | Inge de Bruijn (NED) | 56.61 | Sydney, Australia | 17 September 2000 | – |
The following records were established during the competition:
| Date | Round | Name | Nationality | Time | Record |
| July 28 | Heat 6 | Dana Vollmer | United States | 56.25 | OR |
| July 29 | Final | Dana Vollmer | United States | 55.98 | WR |

## Results
### Heats

| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 6 | 4 | Dana Vollmer | United States | 56.25 | Q, OR, AM |
| 2 | 6 | 5 | Lu Ying | China | 57.17 | Q |
| 3 | 4 | 4 | Alicia Coutts | Australia | 57.36 | Q |
| 4 | 5 | 4 | Sarah Sjöström | Sweden | 57.45 | Q |
| 5 | 6 | 7 | Jeanette Ottesen | Denmark | 57.64 | Q |
| 6 | 6 | 6 | Jiao Liuyang | China | 57.71 | Q |
| 7 | 6 | 3 | Claire Donahue | United States | 58.06 | Q |
| 8 | 4 | 5 | Francesca Halsall | Great Britain | 58.23 | Q |
| 9 | 5 | 5 | Ellen Gandy | Great Britain | 58.25 | Q |
| 10 | 5 | 3 | Inge Dekker | Netherlands | 58.30 | Q, WD |
| 11 | 4 | 8 | Tao Li | Singapore | 58.34 | Q |
| 12 | 5 | 7 | Ilaria Bianchi | Italy | 58.42 | Q |
| 13 | 4 | 2 | Aliaksandra Herasimenia | Belarus | 58.50 | Q, NR |
| 14 | 5 | 2 | Martina Granström | Sweden | 58.70 | Q |
| 15 | 4 | 3 | Yuka Kato | Japan | 58.72 | Q |
| 16 | 4 | 7 | Kristel Vourna | Greece | 58.74 | Q |
| 17 | 5 | 6 | Katerine Savard | Canada | 58.76 | Q |
| 18 | 5 | 8 | Amit Ivry | Israel | 58.78 | |
| 19 | 3 | 3 | Irina Bespalova | Russia | 58.79 | |
| 19 | 6 | 8 | Kimberly Buys | Belgium | 58.79 | |
| 21 | 4 | 1 | Alexandra Wenk | Germany | 58.85 | |
| 22 | 6 | 2 | Ingvild Snildal | Norway | 59.01 | |
| 23 | 5 | 1 | Natsumi Hoshi | Japan | 59.06 | |
| 24 | 4 | 6 | Jessicah Schipper | Australia | 59.17 | |
| 25 | 3 | 5 | Otylia Jędrzejczak | Poland | 59.31 | |
| 26 | 2 | 3 | Danielle Villars | Switzerland | 59.42 | NR |
| 26 | 2 | 4 | Judit Ignacio Sorribes | Spain | 59.42 | |
| 28 | 3 | 7 | Denisa Smolenová | Slovakia | 59.48 | |
| 29 | 3 | 6 | Emilia Pikkarainen | Finland | 59.55 | |
| 30 | 3 | 1 | Hannah Wilson | Hong Kong | 59.59 | |
| 31 | 2 | 7 | Sara Isaković | Slovenia | 59.86 | |
| 32 | 2 | 2 | Sarah Blake Bateman | Iceland | 59.87 | NR |
| 33 | 6 | 1 | Daynara de Paula | Brazil | 1:00.14 | |
| 34 | 3 | 2 | Liliána Szilágyi | Hungary | 1:00.34 | |
| 35 | 2 | 6 | Triin Aljand | Estonia | 1:00.43 | |
| 36 | 3 | 8 | Sara Oliveira | Portugal | 1:00.44 | |
| 37 | 3 | 4 | Birgit Koschischek | Austria | 1:00.54 | |
| 38 | 2 | 5 | Justine Bruno | France | 1:01.14 | |
| 39 | 2 | 1 | Dalia Torrez Zamora | Nicaragua | 1:05.42 | |
| 40 | 1 | 4 | Noel Borshi | Albania | 1:05.49 | |
| 41 | 1 | 3 | Dorian McMenemy | Dominican Republic | 1:05.78 | NR |
| 42 | 1 | 5 | Marie Laura Meza | Costa Rica | 1:07.01 | |

### Semifinals
#### Semifinal 1

| Rank | Lane | Name | Nationality | Time | Notes |
| 1 | 5 | Sarah Sjöström | Sweden | 57.27 | Q |
| 2 | 4 | Lu Ying | China | 57.51 | Q |
| 3 | 3 | Jiao Liuyang | China | 58.04 | |
| 4 | 2 | Tao Li | Singapore | 58.18 | |
| 5 | 1 | Yuka Kato | Japan | 58.26 | |
| 6 | 7 | Aliaksandra Herasimenia | Belarus | 58.41 | NR |
| 7 | 6 | Francesca Halsall | Great Britain | 58.52 | |
| 8 | 8 | Katerine Savard | Canada | 59.22 | |

#### Semifinal 2

| Rank | Lane | Name | Nationality | Time | Notes |
| 1 | 4 | Dana Vollmer | United States | 56.36 | Q |
| 2 | 5 | Alicia Coutts | Australia | 56.85 | Q |
| 3 | 3 | Jeanette Ottesen | Denmark | 57.25 | Q, NR |
| 4 | 6 | Claire Donahue | United States | 57.42 | Q |
| 5 | 2 | Ellen Gandy | Great Britain | 57.66 | Q |
| 6 | 7 | Ilaria Bianchi | Italy | 57.79 | Q, NR |
| 7 | 8 | Kristel Vourna | Greece | 58.31 | NR |
| 8 | 1 | Martina Granström | Sweden | 58.95 | |

### Final

| Rank | Lane | Name | Nationality | Time | Notes |
| | 4 | Dana Vollmer | United States | 55.98 | WR |
| | 7 | Lu Ying | China | 56.87 | |
| | 5 | Alicia Coutts | Australia | 56.94 | |
| 4 | 6 | Sarah Sjöström | Sweden | 57.17 | |
| 5 | 8 | Ilaria Bianchi | Italy | 57.27 | NR |
| 6 | 3 | Jeanette Ottesen | Denmark | 57.35 | |
| 7 | 2 | Claire Donahue | United States | 57.48 | |
| 8 | 1 | Ellen Gandy | Great Britain | 57.76 | |