If you tear your acl, how long does it take to heal if you don't have surgery?

It doesn't: The acl cannot heal on its own. It often scars down around the surrounding structures, but it does not return to normal function without a reconstruction. However, the decision to reconstruct is a very personal and individual decision that should be discussed with your friendly neighborhood orthopedic surgeon / sports medicine surgeon. Take the time to go over your own situation with the surgeon!