How Long Does It Take To Rot Bananas?

This depends on several things, if kept at room temperature, should last for a few days, depends on how ripe they were to begin with. But if you need ripe bananas to cook for instance, in a banana bread, stick in the freezer and they will ripen over night. If you leave on counter, will rot in a matter of hours after thawing

The fridge will rot the fastest

Depends on how ripe they are when you buy them, I've had some rot in about 3 days, which is really annoying.