Perfect ham, every time.
Most supermarket hams are pre-cooked (labeled "fully cooked" or "ready to eat") and only need reheating to 140°F internal. Raw hams must reach 145°F with a 3-minute rest. At 325°F: pre-cooked bone-in ham takes 15-18 min/lb, raw takes 20-25 min/lb, spiral-cut 10-12 min/lb (less because the slices allow heat penetration). Cover with foil for the first 2/3 of cooking to retain moisture, then uncover and apply glaze. Glaze 30 minutes before done — earlier and the sugar burns. For serving: plan ⅓ lb bone-in ham per person (½ lb for big eaters). A 10-lb ham serves 20-30 people. Let ham rest 15-20 min after cooking — the internal temp rises 5-10°F during carryover and juices redistribute.