It changes for every one. It depends on what you mean by average. a good competitive time is about a 1 minute.
World Record 50m Butterfly: Roland Schoeman (South Africa) July 25, 2005 Time: 22.96
For men the World record for 50m freestyle is under 21 seconds, while a reasonable club swimmer should be able to swim 50m freestyle in around 25 seconds. A good time for an average non-club swimmer should be around the 30 second mark
Steffen Deibler holds the world record in the 50m butterfly. http://en.wikipedia.org/wiki/List_of_world_records_in_swimming
For the average 14-year old boy, I would say the average 50m free time would be about a 29.40 sec.
Work on your sprints, breath control, and under water butterfly kick.
so that people can swim in them
It depends on the swim stroke. For Freestyle, the fastest 50m world record is held by a US swimmer named Steve Crocker. The time is: 21.64. For Butterfly, the fastest 50m world record is held by UK swimmer Mark Foster, at 23.55. For Breaststroke, the 50m world record is held by Mark Warnecke of Germany, with a time of 27.00. And for Backstroke, the 50m world record is claimed by another US swimmer, Jeff Rouse, who swam it in just 24.37.
The fastest stroke in swimming is frontcrawl as demonstrated by the 50m World Records below: 50m Frontcrawl = 20.94s 50m Butterfly = 22.43s 50m Backstroke = 24.33s 50m Breaststroke = 26.89s
Speed = distance/time interval = 50m/25min = 2m/min
30.79 seconds
A great swimmer in the 50m.100m freestyle and 50m.100m.200m butterfly. individual medley 200m
50 seconds