Prime Rib Cooking Time Calculator
Roasting time and pull temperature for a standing rib roast, by weight and doneness.
Updated · How we check our maths
- Roasting time
- 2 h – 2 h 16 min
- Oven
- Sear 15 min at 450–500°F, then 325°F
- Time per pound at 325°F
- 15–17 min
- Pull from the oven at
- 125–130°F
- Final temperature after resting
- 130–135°F
- Rest
- 20–30 minutes, loosely tented with foil
- Roast size for 8 guests
- 8 lb bone-in (1 rib feeds 2)
Quick answer
Roast prime rib at 325°F for about 15–17 minutes per pound for medium-rare (13–15 for rare, 17–20 for medium) after a 15-minute sear at 450–500°F. Pull it about 5°F below your target — around 125–130°F for medium-rare — and rest it 20–30 minutes.
What the Prime Rib Cooking Time Calculator does
Enter the weight of your rib roast and how you like it cooked. The calculator gives a roasting window, the temperature to take it out of the oven and the temperature it will reach after resting (carry-over cooking adds about 5–10°F). Add your guest count to check the roast size.
Use an instant-read or probe thermometer in the centre of the roast — time per pound is only a guide.
The formula
Time = weight × minutes per pound (rare 13–15, medium-rare 15–17, medium 17–20, medium-well 20–22 at 325°F), × 0.92 for boneless.
Worked example
An 8 lb bone-in roast, medium-rare: 8 × 15–17 min = 2 h – 2 h 16 min, pulled at 125–130°F.
How to use the Prime Rib Cooking Time Calculator
- Enter the weight of the roast.
- Pick the doneness you want.
- Choose bone-in or boneless.
- Follow the time, but go by the thermometer.
Frequently asked questions
How long to cook a 10 lb prime rib?
About 2½–2¾ hours at 325°F for medium-rare, after searing.
What temperature should I take prime rib out?
About 5°F below your target: ~120°F for rare, 125–130°F for medium-rare, 135–140°F for medium.
How much prime rib per person?
About 1 lb bone-in (one rib feeds two) or ½–¾ lb boneless.
Results are estimates for planning and learning. Check important figures with a qualified professional. How we build and check our calculators.