How much prime rib or ham per person: Christmas dinner calculator
The roast is the centerpiece, and the moment everyone remembers is it coming to the table on time, carved and perfect. Tell it who is eating and when you sit down, and get how much prime rib or ham to buy, how many ribs, when each goes in the oven and a schedule to print. Free, no sign-up, and nothing leaves your browser.
Your Christmas dinner roast plan
Your schedule
Sources: USDA Food Safety and Inspection Service, Hams and Food Safety and Roasting Those Other Holiday Meats. Times are estimates for an oven at 325°F; ovens and roasts vary, so always confirm with a food thermometer.
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Twelve small Christmas rituals for the whole family, one a day, with a little village that lights up as you go. Most take 10 to 20 minutes and need no supplies.
Free tool: 12 days of Christmas activity picker, one family activity a day for your kids' ages and time.
Plan the rest of Christmas dinner
The roast is one dish. The Christmas Dinner Host Planner keeps the whole meal in one place: the guest list, every dish and who brings it, oven times and a day-by-day plan from ordering the roast to carving it.
Guests, dishes, oven times and a day-by-day plan, from ordering the roast to carving it.
See it on Etsy Details
A finished holiday dinner plan for 6, 12 or 24 guests with a kitchen timeline in 15-minute steps.
See it on Etsy Details
More: the free party food and drink calculator, the holiday baking schedule and the holiday party planning checklist.
Prime rib and ham questions
How much prime rib do I need per person?
Plan on about 1 lb per person for a bone-in prime rib, weighed before cooking, or about 1/2 lb per person for boneless. One rib feeds about two people, so a 4-rib roast (about 8 lb) feeds eight. Plan half again as much if you want leftovers. Count young kids as half a portion.
How much ham do I need per person?
About 3/4 lb per person for a bone-in or spiral-sliced ham, and about 1/2 lb per person for boneless. Serving prime rib and ham together, plan each at a bit more than half that, which is what the calculator does.
How long do I cook prime rib, and at what temperature do I take it out?
At 325°F, plan on roughly 15 to 19 minutes per pound for a bone-in roast cooked medium-rare, and longer per pound for boneless, but roasts vary, so a thermometer decides. Take it out at about 115°F for rare, 125°F for medium-rare or 135°F for medium; it climbs a few degrees while it rests for 30 minutes. The USDA's safe minimum for beef roasts is 145°F with at least a 3-minute rest; its holiday roasting chart gives 23 to 30 minutes per pound for a 4 to 8 lb bone-in rib roast and 39 to 43 for a 4 lb boneless one, and the 145°F option uses those times.
How long does it take to heat a fully cooked ham?
The USDA reheats a fully cooked ham at 325°F to 140°F: about 15 to 18 minutes per pound for a whole bone-in ham, 18 to 24 for a half, 10 to 18 for spiral-sliced and 10 to 15 for a vacuum-packed boneless ham. Leftover ham, or ham repackaged outside the plant, should reach 165°F. A ham labelled "cook before eating" is not fully cooked and needs longer.
How long does a frozen roast or ham take to thaw?
In the fridge, allow about 24 hours for every 4 to 5 lb. The calculator uses 4 lb a day to stay on the safe side and gives you the day to move it from the freezer.
Do you store what I type in?
No. Everything is worked out in your browser. Nothing is sent or saved; print the schedule or copy the note before you close the page.