How Long Should You Cook a 1.3 kg Roast Beef? A Detailed Guide

Roast beef is a delicious and impressive main course for any occasion. When cooked correctly, it can be juicy, tender and full of flavor. However, knowing exactly how long to cook a roast beef can be tricky, as the cooking time depends on several factors like the size and thickness of the roast.

In this article I will provide a detailed guide on how long you should cook a 1.3 kg roast beef to achieve perfection. Whether you are cooking roast beef for Sunday dinner or a special event this guide will help you determine the ideal cooking time and technique for a tender, medium-rare roast beef weighing around 1.3 kg.

Key Factors That Affect Roast Beef Cooking Time

Here are some of the key factors that impact the cooking time for roast beef:

  • Weight: Heavier roasts need more time to cook through to the center while reaching the desired doneness on the exterior. A 1.3 kg roast is considered a medium-sized cut of beef.

  • Thickness Thicker cuts of roast beef require longer cooking than thinner ones Ideally, the roast should be around 2-3 inches thick for even cooking

  • Cooking Method: The oven roasting method takes longer than grilling or pan frying. Oven roasting is usually used for a 1.3 kg roast.

  • Desired Doneness: Rare roast beef takes less time to cook than medium or well-done. Medium-rare is usually the preferred doneness for prime rib and other tender cuts.

  • Bone-In or Boneless Bone-in roasts cook slower because the bone partly insulates the meat, Boneless roasts will cook faster

  • Fat Cap: Roasts with an exterior fat cap tend to cook a bit more slowly. The fat basting helps keep the meat tender.

  • Meat Temperature: Always rely on an instant-read meat thermometer for determining when the roast is done.

Now that we’ve covered the key factors, let’s look specifically at how long to cook a 1.3 kg roast beef in the oven.

Calculating the Cooking Time

For a 1.3 kg roast beef, the precise cooking time depends on the shape, thickness, and your desired doneness. Here are some general timelines:

  • For a 2-inch thick boneless roast, cook 15-20 minutes per pound at 300°F. So for 1.3 kg (around 3 lbs), cook for 45 minutes to 1 hour.

  • For a 3-inch thick boneless roast, cook 20-25 minutes per pound at 300°F. For 1.3 kg, cook for 60-75 minutes.

  • For a 2-inch thick bone-in roast, cook 20 minutes per pound at 300°F. For 1.3 kg, cook for 60 minutes.

  • For a 3-inch thick bone-in roast, cook 25 minutes per pound at 300°F. For 1.3 kg, cook for 75-90 minutes.

These timelines are for roasts cooked to medium-rare doneness. For medium or well-done roasts, add 5-10 minutes of cooking time per pound.

Always rely on a meat thermometer over the clock to test for doneness, as oven temperatures can vary. Remove the roast when it reaches the following internal temperatures:

  • Rare: 125-130°F (52-54°C)
  • Medium Rare: 130-135°F (54-57°C)
  • Medium: 140-145°F (60-63°C)
  • Medium Well: 150-155°F (66-68°C)
  • Well Done: 160°F (71°C) or higher

Step-by-Step Method

Follow these simple steps for roasting a tender, juicy 1.3 kg roast beef to medium-rare perfection:

1. Take the Roast Out of the Fridge

Remove the roast from the refrigerator and allow it to come closer to room temperature, about 30 minutes before cooking. This helps it cook more quickly and evenly.

2. Preheat the Oven

Preheat your oven to 300°F (150°C). This moderate roasting temperature prevents the exterior from overcooking while allowing time for the inside to come up to temperature.

3. Prepare the Roast

Pat the roast dry with paper towels. Trim off any excess fat. Apply a light coating of oil over the roast along with your desired seasonings – coarse salt, ground pepper, herbs or spices work well.

4. Use a Roasting Pan

Place the roast fat-side up in a roasting pan. The pan should be just large enough to fit the roast without crowding.

5. Roast Until Desired Internal Temperature

Cook the roast for 45-90 minutes based on the size and thickness. Check the internal temperature periodically. Once it reaches 130°F for medium-rare, remove from the oven.

6. Allow to Rest

Let the roast rest for 15-20 minutes before slicing. This allows the juices to redistribute for a moist, tender texture. The internal temperature will rise a few degrees during resting.

7. Carve and Serve Hot

Carve the roast into thin slices across the grain. Be sure to pour the rested juices from the pan over the sliced beef. Serve hot along with your choice of sides like Yorkshire pudding or roasted potatoes.

And that’s it – follow this simple roasting method to enjoy a perfect medium-rare 1.3 kg roast beef for Sunday dinners or special occasions. The key is starting with a thick, well-marbled cut of beef, seasoning it well, using an accurate meat thermometer, and allowing it to rest before serving.

Tips for the Best Roast Beef

Here are some additional tips to ensure your 1.3 kg roast beef turns out juicy and flavorful:

  • Choose well-marbled prime rib, ribeye, or sirloin tip roasts for the best texture. Grass-fed beef also has excellent flavor.

  • Let the roast sit at room temperature for 30 minutes before roasting for faster, more even cooking.

  • Sear the roast first in a hot skillet to develop a flavorful brown crust before transferring to a 300°F oven.

  • Roast the beef fat-side up so it self-bastes, keeping the meat moist.

  • Use a meat thermometer to check for your desired degree of doneness – never solely rely on the clock.

  • Allow the roast to rest for 10-20 minutes before slicing to retain juices.

  • Carve across the grain into thin slices for the most tender texture.

  • Pair roast beef with horseradish, au jus, or rich gravy for serving. Roasted veggies also make excellent accompaniments.

Common Roasting Problems and Solutions

Here are some common problems that can occur during roast beef cooking and how to avoid them:

  • Undercooked roast: Increase oven temperature to 325°F and continue roasting until it reaches the minimum safe internal temperature.

  • Overcooked, dry roast: Don’t cook it beyond 130°F for medium-rare doneness. Also, let the roast rest before slicing to maximize juiciness.

  • Burned exterior: Lower the oven temperature and tent foil over the roast if browning too quickly. The foil helps reflect heat.

  • Not flavorful enough: Make sure to generously season the exterior of the roast with salt, pepper, garlic, or other robust spices and herbs.

  • Takes too long to cook: Allow roast to sit at room temperature before cooking. Also, use a meat thermometer to determine doneness rather than oven time.

  • Uneven cooking: Rotate the roasting pan periodically so all sides cook evenly. Also, let it rest before slicing to allow juices to redistribute.

Sample Roast Beef Recipes

To give you some recipe inspiration, here are a couple delicious roast beef entrees to try out for your next meal:

Herb-Crusted Roast Beef

Coat a 1.3 kg beef roast with Dijon mustard, rosemary, thyme and garlic. Roast at 300°F for 60-75 minutes until medium-rare.

Roast Beef with Gravy

Season a 1.3 kg sirloin tip roast with salt and pepper. Roast at 325°F for 1 hour. Make a gravy using the drippings for serving.

Coffee-Spiced Roast Beef

Rub a 1.3 kg ribeye roast with an espresso, coriander, cumin and brown sugar blend. Roast at 300°F for 1-1.5 hours until medium-rare.

Roast Beef Tenderloin

Coat a 1-1.3 kg beef tenderloin with olive oil, salt and pepper. Roast at 400°F for 30-40 minutes for medium-rare doneness.


Got some other questions on roasting times for a 1.3 kg beef roast? Here are answers to some frequently asked questions:

How long should I cook a 1.3 kg rump roast?

For a 1.3 kg rump roast, cook it approximately 1 hour 15 minutes to 1 hour 30 minutes at 300°F oven temperature. Use a meat thermometer for medium-rare doneness.

What temperature is best for roasting a 1.3 kg beef roast?

Cook it between 300-325°F. Higher heat risks burning the exterior before the inside cooks through. Lower heat will increase the cooking time considerably.

Can I roast a 1.3 kg beef roast at 350°F?

Yes, you can cook a roast at 350°F but watch it closely and tent with foil if the top browns too quickly before the inside cooks through. Lower to 300°F if needed.

How long does a 1 kg roast beef take to cook?

For a boneless 1 kg (2.2 lbs) roast, cook for around 45-60 minutes at 300°F for medium-rare doneness, based on thickness. Check temperature rather than time.

Should you sear roast beef before cooking it?

Searing or browning the roast first helps develop delicious caramelized flavor. Use a hot skillet with oil for 1-2 minutes per side before transferring to the oven.


Cooking roast beef can seem daunting, but when armed with the right timelines and technique, you can serve up a perfectly roasted 1.3 kg beef roast. For optimal flavor, moisture and tenderness, cook the roast to medium-rare doneness at 300°F, use a meat thermometer to test for readiness, and be sure to let it rest before slicing. With this complete guide, you’ll be prepared to roast beef like a pro for any occasion.

Classic Roast Beef

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