Tag:amenity=gym (Don't use)
|amenity = gym|
|Using this tag is discouraged, use leisure=fitness_centre instead.|
|Used on these elements|
|Tools for this tag|
|This feature has been labeled as deprecated. The recommended replacement is: leisure=fitness_centre. You are still free to continue to use or interpret this tag as you see fit since OpenStreetMap does not have "banned features".
Under no circumstances should you (semi-)automatically change "deprecated" tags to something else in the database on a large scale without conforming to the Automated Edits code of conduct.
1: leisure not amenity
Most people seem to agree that 'leisure' would be better than 'amenity' as the key to use.
See Gym / Fitness centre#leisure not amenity for details.
2: Ambiguity of the word "gym"
"Gym" has two meanings which are quite different (though from the same origins). Native english speakers are most likely thinking of a Gym / Fitness centre when they use the word, but others often get it confused with Gymnasium. From this ambiguity we might conclude that using the word gym in a tag is a bad idea.
See Gym / Fitness centre#Ambiguity of the word gym. Details of this problem have been moved to there.
Which tag to use?
If you are mapping a gym as in fitness centre see Gym / Fitness centre, where various options are presented (unfortunately the "correct" tag to use has not been widely agreed upon yet).
If you are mapping a gymnasium see Gymnasium.