What are the butterfly races, and what are the rules?
B · Beginner · The stroke · 1 of 6Butterfly is swum on the breast over 50 m, 100 m and 200 m. Both arms go forward over the water together and back under it together, and the legs kick up and down together. Every turn and the finish need a touch with both hands at once. The swimmer must surface by 15 m after the start and each turn.
How it works
- The distances: 50 m, 100 m and 200 m for men and for women.
- The start: a dive from the starting platform.
- On the breast: the body stays on the breast. Rolling onto the back is not allowed.
- The arms: forward over the water together and back under the water together.
- The legs: up and down together. A breaststroke kick is not allowed.
- Under water: no more than 15 m after the start and after each turn.
- The wall: both hands touch at the same time at every turn and at the finish.
- The winner: the fastest time, recorded to a hundredth of a second by touch panels on the wall.
Tricky cases
Can a butterfly swimmer use a breaststroke kick to rest?
No. A breaststroke kicking movement is not permitted.
Can a butterfly swimmer touch the wall with one hand?
No. The touch at each turn and at the finish must be made with both hands at the same time.
Is there a 400 m butterfly?
No. The distances are 50 m, 100 m and 200 m.
Why the rule exists
Butterfly grew out of breaststroke, and its rules keep the two apart. Both arms must recover over the water, and the kick must go up and down, so the stroke cannot slide back into a faster kind of breaststroke.
Where it differs
| Where | What changes | Source |
|---|---|---|
| World Aquatics rules | As above | SW 1.2; SW 8 |
| World Championships in 25 m pools | The same three distances | SW 1.4 |
| Junior and other events | The programme is set in the same article for each championship | SW 1.5 |
From the rule book
World Aquatics, Competition Regulations, Part Two: Swimming Rules (in force as from February 2026), Articles 1.2 to 1.5 and 8. Checked 14 October 2026. Official document: World Aquatics Competition Regulations (PDF).