How long before a hand fracture heals?

Rather quickly... Compared to other bones. Hand fractures are often healed in 3-4 weeks. At that point they will often not appear to be healed on xrays but these lag behind the actual healing. Because stiffness in the hand is much more common than poor fracture healing, immobilization of hand fractures needs to be for as short a time as possible.
It depends. Fracture healing depends on a number of fractures including the severity of the break, the treatment the fracture receives, and the health of the patient. Small bones of the hand and foot usually heal within 6 weeks but some bones are much slower to heal.
4 weeks. Average healing time within a cast or splint is approximately 4 weeks however the bone remodelling takes place over 10-12 weeks. You can be out of a cast in 4 weeks but need to remember that the healing is ongoing and therefore the bone is still fragile and prone to getting fractured easily for up to 3 months.