My answer is for those who are looking for activities beyond academics. 

Inside campus

• Hang out with your friends at OAT or play games here. The best time is winter afternoons or summer evenings
• CCD is one of the most visited places among IIT Kanpur students and most students can be seen chilling here
• You can spend your time at the society or club you are part of 
• Cycling around the campus is another healthy and interesting way of spending time on campus. You can enjoy the natural beauty and feel the fresh air
• Invite your friends to your rooms and have dinner or play games
• Visit the airstrip with your friends and get some nice photos clicked
• Be a part of any sports you are fond of as IIT Kanpur has one of the finest sports facilities. 
• Some loners like to spend their time alone doing nothing or watching movies and TV series or anything of their choice.

Outside campus:

• Z-Square Mall: This mall is a famous place among Kanpurites with many decent eateries, outlets of international brands, and a separate gaming zone too!
• Bithoor: Bithoor is a faraway area with a scenic Brie perfect for cycling trips with friends
• Restaurants: Kanpur has many new restaurants and cafés to hand out.