For a standard precooked ham, you are not really “cooking” it from raw, just heating it through until it is safely hot and juicy, usually to an internal temperature of about 140–145°F.

Basic oven guideline

  • Most precooked, bone‑in hams are heated at 275–325°F.
  • Plan about 12–20 minutes per pound, depending on brand instructions and oven temperature.
  • Use a meat thermometer and heat until the thickest part of the ham reaches about 140–145°F, then rest 10–15 minutes before slicing.

Quick time examples

  • 4–6 lb precooked ham: roughly 1–2 hours in the oven.
  • 8–10 lb precooked ham: about 2–3 hours in the oven; similar size in slow cooker is often 4–6 hours on Low.
  • Large 16–18 lb precooked ham: around 4–4½ hours at 325°F, checking with a thermometer near the end.

Simple step‑by‑step

  1. Preheat oven to 275–325°F (follow any package directions first).
  1. Place ham cut‑side down in a roasting pan, add a little water to the pan, and cover tightly with foil so it doesn’t dry out.
  1. Heat for the estimated time (minutes per pound), basting with pan juices or glaze once or twice if you like.
  1. In the last 10–15 minutes, you can uncover, add glaze, and increase the oven to brown the outside.
  1. Remove when it reaches 140–145°F internally and let it rest before carving.

Slow cooker option

  • Place the precooked ham in a slow cooker on Low for about 2–5 hours, depending on size, until it reaches about 140°F inside.
  • This works well for 4–10 lb hams and keeps them very moist.

Quick safety and quality tips

  • Always follow the specific time/temperature on the ham’s label first; the minutes‑per‑pound numbers are just general guides.
  • The main goal is a safe internal temp without drying the meat out, so use time as a rough estimate and temperature as the final decision.

Information gathered from public forums or data available on the internet and portrayed here.