Some people can rupture their Achilles tendon and get no pain at all from it. In other people it can be quite painful, so an Achilles tendon rupture is very variable in how painful it is.
The typical symptoms of an Achilles tendon rupture are:
-A feeling of having been kicked or stabbed in the calf
-There will be pain from the area of the tear
-You can not raise up on to the toes on the injured leg (or if you can, it is a lot more difficult)
-You might hear a popping or snapping sound as the injury occurs