How much recovery time do you need after a broken ankle cast?

Will vary. A simple rule of thumb: for every day you are immobilized (crutches, splint, cast, cast boot, etc), it will take you two days to recover fom the immobilization. If you are immobilized for 6 weeks, it will take an addition 12 weeks to feel like you have recovered. This is not hard and fast, but is a simple guide. There are may factors tht play into your recovery. Dr zl.
3 months on average. Ankle fractures can vary on severity but typically most fractures heal within 3 months. But often for severe fractures it can take 6 months to a year for a full recovery.
Recovery time varies. Recover time will vary depending on many factors including age, general health of the patient, infection control, smoker or not, blood sugar control, surgery or no surgery the exact type of procedure, and post-operative and follow up care. Discuss it with your surgeon and get their opinion as to what they feel is a reasonable recovery time for you.