How long to cook prime rib, by weight
2 hr 20 min to 2 hr 30 min
In the oven at 2:25 pm to serve at 5:00 pm: 2 hr 30 min plus 3 min of rest.
Pounds, with decimals or fractions — 14.5 or 14 1/2. Kilograms work too.
A 6 lb bone-in prime rib (rib roast) roasts for 2 hr 20 min to 2 hr 30 min at 325 °F, to 145 °F on a thermometer.
Source: USDA FSIS, Beef From Farm to Table, read Oct 1, 2026.
Prime rib is the rib roast of the USDA FSIS beef chart: 23 to 25 minutes a pound at 325 °F with the bone in, and 5 to 8 more a pound boneless and rolled. The chart gives the safe minimum, 145 °F after at least 3 minutes of rest; cook it longer if you like it more done. Dinner at 5:00 pm with a 6 lb bone-in prime rib (rib roast) means the oven at 2:25 pm.
How the time is worked out
- Oven at 325 °F for rib, round and rump roasts; 425 °F for a whole tenderloin, which the chart gives as a total time rather than per pound.
- Safe minimum of 145 °F on a food thermometer, then at least 3 minutes of rest, counted into the oven time.
- Boneless rolled rib roast: the chart says to add 5 to 8 minutes a pound to the bone-in figure, so 28 to 33 a pound.
- Chuck roast and brisket are braised: 1½ to 2½ hours for a 3 to 4 lb piece, whatever the exact weight.
- Minutes per pound times the weight, rounded to 5 minutes; the oven time uses the top of the range.
- The chart was written for 4 to 6 lb rib roasts; a bigger one uses the same minutes per pound and the calculator says so.
USDA FSIS chart: approximate beef cooking times
Every row of the FSIS beef chart as printed: roasts by the pound, steaks and patties by the side.
| Type of beef | Size | Method | Cooking time | Internal temperature |
|---|---|---|---|---|
| Rib roast (prime rib), bone in | 4 to 6 lb | Roast 325 °F | 23-25 min./lb. | 145 °F, rest 3 min |
| Rib roast, boneless rolled | 4 to 6 lb | Roast 325 °F | Add 5-8 min./lb. to times above | 145 °F, rest 3 min |
| Chuck roast or brisket, braised | 3 to 4 lb | Braise 325 °F | 1 1/2 to 2 1/2 hours | 145 °F, rest 3 min |
| Round or rump roast | 2.5 to 4 lb | Roast 325 °F | 30-35 min./lb. | 145 °F, rest 3 min |
| Tenderloin, whole | 4 to 6 lb | Roast 425 °F | 45-60 min. total | 145 °F, rest 3 min |
| Steaks | ¾ in thick | Broil or grill | 4-5 min. per side | 145 °F, rest 3 min |
| Stew or cross-cuts | 1 to 1½ in thick | Cover with liquid; simmer | 2 to 3 hours | 145 °F, rest 3 min |
| Short ribs | 4 in long and 2 in thick | Braise 325 °F | 1 1/2 to 2 1/2 hours | 145 °F, rest 3 min |
| Hamburger patties, fresh | 4 ounces | Grill, broil or fry | 3 to 5 minutes per side | 160 °F |
Prime rib cooking time by weight: bone in, boneless and round roast
325 °F oven, to 145 °F with 3 minutes of rest. Minutes per pound from the FSIS chart times the weight.
| Weight | Prime rib | Boneless rib roast | Round roast |
|---|---|---|---|
| 3 lb | 1 hr 10 min–1¼ hr | 1 hr 25 min–1 hr 40 min | 1½–1¾ hr |
| 4 lb | 1½ hr–1 hr 40 min | 1 hr 50 min–2 hr 10 min | 2 hr–2 hr 20 min |
| 5 lb | 1 hr 55 min–2 hr 5 min | 2 hr 20 min–2¾ hr | 2½ hr–2 hr 55 min |
| 6 lb | 2 hr 20 min–2½ hr | 2 hr 50 min–3 hr 20 min | 3–3½ hr |
| 7 lb | 2 hr 40 min–2 hr 55 min | 3¼ hr–3 hr 50 min | 3½ hr–4 hr 5 min |
| 8 lb | 3 hr 5 min–3 hr 20 min | 3¾ hr–4 hr 25 min | 4 hr–4 hr 40 min |
| 10 lb | 3 hr 50 min–4 hr 10 min | 4 hr 40 min–5½ hr | 5 hr–5 hr 50 min |
| 12 lb | 4 hr 35 min–5 hr | 5 hr 35 min–6 hr 35 min | 6–7 hr |
Where these numbers come from
The chart is USDA FSIS, Beef From Farm to Table (fsis.usda.gov), read on October 1, 2026; FSIS last updated that page on December 4, 2024. What this page takes from it: Approximate beef cooking times: minutes per pound and oven temperature by cut (rib roast bone in and boneless, round or rump, tenderloin, braised cuts), with 145 °F and at least 3 minutes of rest. The figures are copied as printed; the calculator multiplies by your weight, rounds to 5 minutes and counts back from your serving time.
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