Here’s the rule of thumb: heat that ham to an internal temperature of 140°F. Why 140? Because it’s warm enough to kill any surface germs (we’re polite, not paranoid) and melt the fat into buttery bliss. Don’t overshoot 160°F, or you’ll get dry, sad ham.
Time depends on size and style. A whole ham (10–15 pounds) needs about 15–18 minutes per pound at 325°F. A half ham (5–7 pounds) clocks in at 18–20 minutes per pound. Spiral-sliced? Less time—maybe 10–12 minutes per pound, because slices heat faster.
The Foolproof Method
Preheat your oven to 325°F. Place the ham in a roasting pan, cut side down. Add a splash of water (or apple juice—trust me) to the bottom of the pan. Cover it tight with foil so steam does the work.
Pop it in. Set a timer for 10 minutes per pound, then start checking with a meat thermometer. Insert it deep into the thickest part, but avoid hitting bone (it lies about temperature). When it reads 140°F, you’re done.
