How long does it normally take for an avulsion ankle fracture to heal?

Depends: If the avulsuion only involves the very tip of the lateral ankle then it is really treated like a severe ankle sprain. Either way, getting involved in a good ankle rehabilittion program will help and you should be able to get back to sports in about 4-6 weeks.

4-8 weeks: The pain of an avulsion ankle of the ankle (usually the outside or lateral part/fibula) lasts about 4-8 weeks. It requires a cast or a brace and is treated symptomatically, being allowed to walk on it as pain is tolerated. Often it "heals" but the fragment remains separate , if it is asymptomatic it is left alone. If pain persists at times it requires surgery