How long a roast needs in the oven depends on more than its weight — the cut matters just as much. A bone-in prime rib and a boneless sirloin roast of the same weight can differ by several minutes per pound, because bone conducts heat into the center faster than pure muscle does. This calculator uses cut-specific rates instead of one generic beef/pork/lamb number.
Why cut matters more than meat type alone
A generic "beef roasting time" chart treats a bone-in prime rib the same as a boneless sirloin roast, but the two cook at meaningfully different rates. Bone conducts heat efficiently, so bone-in roasts like prime rib and leg of lamb finish faster per pound than boneless roasts of the same weight. That's why this calculator looks up a rate by cut, not just by meat type — using a single beef rate for both prime rib and sirloin would systematically overcook one or undercook the other.
Sources: USDA measured minimum temperatures
Doneness preference vs. food safety
For medium or USDA-safe whole cuts, measure at least 145°F before heat removal and rest at least 3 minutes. Rare and medium-rare are below-minimum culinary preferences. Carryover varies and must not substitute for a measured endpoint.
Time is a plan, temperature is the test
Every number this calculator produces — total time, pull temperature, rest time — is a planning estimate. Oven calibration, a roast's exact shape, and its starting temperature (straight from the fridge vs. brought to room temperature) can shift the actual time by 15-20 minutes or more in either direction. The only reliable way to know a roast is done is a food thermometer inserted into the thickest part, away from bone. Use the minutes-per-pound estimate to plan your schedule, then confirm with temperature before you pull it from the oven.