An estimated cooking time from the type and weight of meat — paired with the safe internal temperature to check with a food thermometer and the rest time to allow.
Estimates only. Internal temperature, measured with a food thermometer in the thickest part away from bone, is the reliable test of doneness — times vary with oven, starting temperature, shape and bone.
Roasting time scales roughly with weight, at a rate that depends on the meat and cut: this calculator multiplies the weight by a typical minutes-per-pound rate for the selected meat at a moderate oven temperature (around 325-350 F / 165-175 C) and adds the recommended rest time. The figures that matter most are the safe internal temperatures — the USDA minimums shown with each result, such as 165 F (74 C) for poultry and 145 F (63 C) plus a rest for beef, pork and lamb roasts. Those temperatures, checked with a food thermometer, override any time estimate.
Can cooking time alone tell if meat is safe? No. Shape, bone, starting temperature and oven accuracy all shift the time, sometimes by a wide margin. Time is a planning guide; a food thermometer reading at or above the safe temperature for that meat is the check to rely on.
Why rest the meat afterwards? Resting lets juices redistribute so less runs out when carving, and for roasts cooked to 145 F the rest is part of the safety guidance — the temperature holds while surface bacteria continue to be reduced. Tent loosely with foil and allow the rest time shown.