About the Roast Cooking Time Calculator
This roast cooking time calculator estimates how long a joint of meat needs in the oven from its weight, the cut and how you like it cooked. It covers bone-in prime rib, leaner beef roasts, pork loin, slow-roasted pork shoulder, leg of lamb and whole chicken, and tells you the oven temperature, the internal temperature at which to take the roast out, how long to rest it and what time to put it in the oven so dinner is ready on time.
Use it for holiday prime rib, Sunday roasts and dinner parties. Minutes-per-pound figures are planning estimates for a roast that starts at fridge temperature in a conventional oven; the shape of the joint, bone, oven accuracy and convection fans all change the real time, so always finish by temperature with an instant-read or probe thermometer.
Pull temperatures sit about 5°F below the target because the roast keeps cooking as it rests (carryover cooking). USDA guidance is 145°F with a 3-minute rest for whole cuts of beef, pork and lamb and 165°F for poultry; rare and medium-rare beef and lamb are below the USDA minimum. The per-pound rates follow the USDA FSIS roasting charts where USDA publishes one (bone-in rib roast 23–30 min/lb, eye round 20–22, boneless pork loin 23–33 and leg of lamb 20–26 min/lb at 325°F; a 3–4 lb chicken 1¼–1½ hours at 350°F). USDA's times are for roasts cooked to 145°F, so the rarer beef and lamb rates here are proportionally shorter estimates. Pulled pork shoulder is not in the USDA chart; its 45 min/lb at 325°F is a cooks' rule of thumb. USDA advises against roasting meat at oven temperatures below 325°F.
With the default inputs, the roasting time is 2h 6m. Change any value above to recalculate instantly.
How to use the roast cooking time calculator
- 1Choose the cut of meat you are roasting.
- 2Enter its weight in pounds or kilograms.
- 3Pick your preferred doneness for beef or lamb.
- 4Set the time you want to serve to get the oven-in time.
- 5Roast at the given temperature and remove at the pull temperature on a thermometer.
Formula and method
Each cut has a planning rate in minutes per pound at a set oven temperature — for example about 21 minutes per pound for medium-rare prime rib at 325°F, 25 for a boneless pork loin at 325°F and 22 for a whole chicken at 350°F. Medium beef and lamb rates sit inside the USDA FSIS chart ranges for cooking to 145°F; rarer rates are shorter and well-done rates longer, because the centre must reach a lower or higher temperature. Treat every rate as an approximation: real times vary with the roast's thickness, bone, starting temperature and oven. Kilograms are converted at 2.2046 lb per kg.
The pull temperature is the internal reading at which to remove the roast; it then rises around 5°F while resting. Resting times of 10–30 minutes let juices redistribute. Working backwards from your serving time gives the time to put the roast in, and preheating adds about 20 minutes before that.
- Minutes per lb
- Planning rate for the cut, oven temperature and doneness
- Rest
- Resting time after the roast leaves the oven
Worked examples
6 lb prime rib, medium-rare, serve at 6 pm
6 lb × 21 min/lb = 126 minutes (2 h 6 m) at 325°F. Add a 20-minute rest and the roast must go in 146 minutes before 6:00 pm, at 3:34 pm. Pull it at 130°F; it will coast to about 135°F.
1.5 kg pork loin, serve at 7:30 pm
1.5 kg is 3.31 lb; at 25 minutes per pound that is about 83 minutes at 325°F. With a 10-minute rest (93 minutes in total), it goes in at 5:57 pm and comes out at 140°F to finish at the USDA-recommended 145°F.
7 lb leg of lamb cooked medium
At 25 minutes per pound a 7 lb bone-in leg needs about 175 minutes (2 h 55 m) at 325°F. With a 15-minute rest it should go in at 9:50 am for a 1 pm lunch.
Frequently asked questions
How long do you cook a prime rib per pound?+
USDA's roasting chart gives 23–30 minutes per pound at 325°F for a 4–8 lb bone-in rib roast cooked to 145°F (medium). This calculator plans about 19 min/lb for rare, 21 for medium-rare, 23 for medium and 27 for well done. Always confirm with a thermometer: pull at about 130°F for medium-rare.
What temperature should I take a roast out of the oven?+
Remove it about 5°F below your target because carryover cooking continues while it rests: roughly 120°F for rare beef, 130°F for medium-rare, 140°F for medium and 140°F for pork loin (finishing at the USDA-recommended 145°F).
How long should a roast rest?+
Rest most beef, lamb and pork roasts 10–20 minutes loosely tented with foil, and large prime ribs or pork shoulders 20–30 minutes. Resting lets the temperature equalise and keeps juices in the meat when you carve.
Do I cook a roast covered or uncovered?+
Roast beef, lamb, pork loin and chicken uncovered on a rack so hot air browns the outside. Cover only if the surface is browning too fast, or for braised cuts cooked in liquid.
What is the safe internal temperature for roasts?+
USDA recommends 145°F with a 3-minute rest for whole cuts of beef, pork, veal and lamb, and 165°F for all poultry. Ground meats should reach 160°F. Rare and medium-rare beef are cooked below the USDA minimum.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.