Cooking guide · Bar 7 Beef
How to Cook Prime Rib
Prime rib is one of the most impressive roasts you can put on a table — and one of the most forgiving, as long as you cook by internal temperature rather than by the clock. This guide walks through oven preparation, seasoning, cooking, resting and carving.
A note on timing: every cooking time below is an estimate. Ovens, roast shape and starting temperature all vary, so internal temperature — not time — determines doneness. Use a meat thermometer.
Before the Oven
- Thaw completely. A frozen or partially frozen roast cooks unevenly. Thaw in the refrigerator — allow roughly 24 hours for every 2–2.5 kg.
- Bring toward room temperature. Take the roast out of the fridge 1–2 hours before cooking so it cooks more evenly.
- Season generously. Pat the roast dry, then season all sides with salt and pepper. Garlic, rosemary and thyme are classic additions. Seasoning ahead (even the night before, uncovered in the fridge) helps the crust.
- Set up the pan. Place the roast bone-side down (the bones act as a rack) or on a rack in a roasting pan, fat side up.
Cooking Instructions
- Preheat the oven to 230°C (450°F).
- Roast at 230°C (450°F) for 15–20 minutes to develop a browned crust.
- Reduce the oven to 160°C (325°F) and continue roasting until the internal temperature approaches your target (see the chart below).
- Start checking the temperature about 30–45 minutes before the estimated time is up.
Approximate Cooking Time by Weight
At 160°C (325°F) after the initial high-heat sear, aiming for medium-rare. These are estimates only — always confirm with a thermometer.
| Roast weight | Approximate total time |
|---|---|
| 2–2.5 kg (4.5–5.5 lb) | About 1¾–2¼ hours |
| 3–3.5 kg (6.5–7.5 lb) | About 2¼–3 hours |
| 4–5 kg (9–11 lb) | About 3–3¾ hours |
Thermometer Placement & Target Temperatures
Insert the thermometer into the thickest part of the roast, away from bone and fat. Bone conducts heat differently and gives a false reading.
Doneness preferences (whole-cut roast): many cooks pull prime rib at 52–57°C (125–135°F) for rare to medium-rare, knowing the temperature will rise several degrees while resting. These are taste preferences, not food-safety recommendations.
Food safety: Health Canada recommends whole-cut beef roasts reach a minimum internal temperature of 63°C (145°F). If you prefer your prime rib below that, that's a personal choice — but guests who are pregnant, elderly, very young or immunocompromised should be served beef cooked to the safe minimum.
For the official guidance, see Health Canada's safe internal cooking temperatures, or our beef cooking temperatures guide.
Resting & Carving
- Rest 20–30 minutes. Tent loosely with foil. The internal temperature will rise a few degrees and the juices will redistribute — skip this and they end up on the cutting board.
- Remove the bones. For a bone-in roast, cut along the bone to separate it before slicing.
- Slice across the grain into slices about 1–2 cm (½–¾ inch) thick, using a long, sharp carving knife.
Cook Beef from Our Ranch
Our beef boxes include roasts and steaks raised on our Cariboo ranch near Quesnel, BC.