How this calculator works
The USDA Food Safety and Inspection Service says to buy 1/3 to 1/2 pound of meat per serving of bone-in ham and 1/4 to 1/3 pound per serving of boneless ham. Children count as half. The time is the USDA timetable for ham at 325°F, in minutes per pound for each cut, and the safe temperature depends on the kind of ham.
Worked example: 10 adults and 2 children is 11 servings. At the high end of the range for bone-in ham (1/2 lb) that is a 6 lb half ham. A cooked half ham takes 18 to 24 minutes per pound, so 108 to 144 minutes at 325°F, until it reaches 140°F.
Assumptions and sources
The assumptions behind your numbers (waste, sizes, rates) are listed in the notes directly under your results, and they update when you change an input.
The formula and a worked example are shown above, so you can check any result by hand. Read how we calculate and check our numbers. Results are estimates for planning: supplier products vary, so check the size printed on the label.
Ham to buy by number of guests
USDA serving sizes: bone-in 1/3 to 1/2 lb, boneless 1/4 to 1/3 lb per person. Pounds rounded up.
| Guests | Bone-in, low | Bone-in, high | Boneless, low | Boneless, high |
|---|---|---|---|---|
| 4 | 2 lb | 2 lb | 1 lb | 2 lb |
| 6 | 2 lb | 3 lb | 2 lb | 2 lb |
| 8 | 3 lb | 4 lb | 2 lb | 3 lb |
| 10 | 4 lb | 5 lb | 3 lb | 4 lb |
| 12 | 4 lb | 6 lb | 3 lb | 4 lb |
| 15 | 5 lb | 8 lb | 4 lb | 5 lb |
| 20 | 7 lb | 10 lb | 5 lb | 7 lb |
| 25 | 9 lb | 13 lb | 7 lb | 9 lb |
| 30 | 10 lb | 15 lb | 8 lb | 10 lb |
Tips before you buy
- Fully cooked hams from a USDA-inspected plant can be eaten cold. If you reheat one, set the oven no lower than 325°F and heat it to 140°F.
- A bone-in ham needs more weight per person because the bone is part of what you buy. Boneless ham is all meat, and carves easily.
- Cover a spiral-cut ham with heavy foil before reheating, so the slices stay moist and the glaze does not run off.
- Add the glaze for the last 20 to 30 minutes only, since sugar burns in a long bake.
- Check the label first: a "cook before eating" ham needs 145°F and a 3 minute rest, and a country ham needs soaking and boiling.
- Ham is the usual second meat for a big Thanksgiving: it cooks faster than a big turkey. See the turkey size calculator for the bird.
Tools & materials for this project
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Frequently asked questions
How much ham per person?
The USDA gives 1/3 to 1/2 pound of meat per serving of bone-in ham and 1/4 to 1/3 pound per serving of boneless ham. Go to the top of the range if the ham is the main dish, and above it if you want sandwiches the next day.
How big a ham for 12 people?
6 lb of bone-in ham or 4 lb of boneless ham for 12 adults, at the high end of the USDA range.
How long does it take to reheat a ham?
A cooked half ham of 6 lb takes 108 to 144 minutes at 325°F, 18 to 24 minutes per pound. Whole hams, spiral-cut hams and boneless hams have their own times in the calculator.
What temperature should ham be cooked to?
A cook-before-eating or fresh ham needs 145°F with a 3 minute rest. A fully cooked ham from a USDA-inspected plant is reheated to 140°F, and leftover or repackaged ham to 165°F.
Do I have to cook a ham that is fully cooked?
No. Fully cooked, vacuum-packed hams can be eaten cold straight from the package. Reheating is for taste, and the oven should be at 325°F or higher.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.