Setting your oven to 300°F gives roast a gentle, even cook that breaks down connective tissue without drying out the exterior. If you want to know how long to cook roast at 300 in oven, plan on roughly 20 to 30 minutes per pound for most beef cuts, though the exact time depends on the size of the roast and the type of meat your working with.
This guide breaks down the timing for beef, pork, and lamb, plus the internal temperatures you need to hit for a safe, tender result.
Why 300°F Works So Well For Roast
Low and slow heat is the friend of tough cuts. At 300°F, the collagen in the meat slowly melts into gelatin, which is what makes a chuck roast or brisket taste so rich and soft.
A hotter oven cooks the outside fast and leaves the middle chewy. A 300°F oven keeps the whole roast cooking at a more even pace.
The trade off is time. You will wait longer, but the meat rewards you with better texture and less shrinkage.
How Long To Cook Roast At 300 In Oven
Use this chart as your starting point. Always confirm doneness with a meat thermometer, because oven temps vary and roast shape matters.
Beef Roast Timing At 300°F
- Beef chuck roast: 25 to 30 minutes per pound
- Beef brisket: 30 to 35 minutes per pound
- Beef round roast: 20 to 25 minutes per pound
- Beef tenderloin: 15 to 20 minutes per pound
- Prime rib: 18 to 22 minutes per pound
Pork Roast Timing At 300°F
- Pork shoulder or butt: 30 to 35 minutes per pound
- Pork loin roast: 20 to 25 minutes per pound
- Pork tenderloin: 15 to 20 minutes per pound
Lamb Roast Timing At 300°F
- Lamb shoulder: 25 to 30 minutes per pound
- Leg of lamb: 20 to 25 minutes per pound
- Rack of lamb: 15 to 18 minutes per pound
For a 3 pound beef chuck roast, that means about 75 to 90 minutes. A 5 pound pork shoulder could take 2.5 to 3 hours. Write down your start time so you don’t have to guess later.
Internal Temperatures You Must Hit
Time per pound is a guide, not a rule. The thermometer is the real judge. Insert it into the thickest part, away from bone and fat.
- Beef medium rare: 135°F
- Beef medium: 145°F
- Beef well done: 160°F
- Pork: 145°F with a 3 minute rest
- Lamb medium rare: 135°F
- Lamb medium: 145°F
For tough cuts like chuck and shoulder, you actually want to push past the safe minimum. These cuts get tender around 195°F to 205°F, where the connective tissue fully breaks down.
Step By Step Cooking Method
- Take the roast out of the fridge 30 to 60 minutes before cooking. A room temp roast cooks more evenly.
- Pat the meat dry with paper towels. Dry surface equals better browning.
- Season generously with salt and pepper. Add garlic, rosemary, or thyme if you like.
- Heat a skillet over high heat and sear all sides for 2 to 3 minutes per side. This step is optional but adds flavor.
- Place the roast on a rack in a roasting pan. Add a cup of broth or water to the bottom to keep things moist.
- Cook uncovered at 300°F for the estimated time based on weight.
- Start checking with a thermometer 20 minutes before your target time.
- Rest the roast for 15 to 30 minutes before slicing. This lets the juices settle.
Tips To Keep Your Roast Moist
- Do not open the oven door often. Each peek drops the temp and adds cooking time.
- If the top browns to fast, tent it loosely with foil.
- Add liquid to the pan so drippings don’t burn and smoke.
- Let the roast rest. Cutting early loses juice and dries out the meat.
- Slice against the grain for a more tender bite.
Common Mistakes To Avoid
Relying Only On Time
Every oven runs a little hot or cold. A cheap thermometer in your oven can show you the real temp. But the meat thermometer is what matters most.
Cooking At 300°F Then Slicing Right Away
Resting is not optional. Skip it and the juices run out onto the board instead of staying in the meat.
Using The Wrong Cut For The Time
A tenderloin at 30 minutes per pound will overcook. A chuck roast at 15 minutes per pound will stay tough. Match the cut to the timing.
How To Tell When Your Roast Is Done
Use a digital meat thermometer for the best accuracy. Check in two spots if the roast is uneven in shape.
If you don’t have a thermometer, pierce the thickest part with a fork. A done chuck roast twists easily and shreds with light pressure. A tenderloin should feel firm but still give a little.
Remember that meat keeps cooking as it rests. Pull it out 5 to 10 degrees below your target temp.
Storing And Reheating Leftovers
Cool the roast within two hours of cooking. Store slices in a sealed container in the fridge for up to four days.
Reheat gently at 300°F with a splash of broth, covered, until warm. High heat in a microwave will dry it out fast.
With the right timing and a good thermometer, a 300°F oven turns even cheap cuts into a tender, flavorful meal. Start with the per pound estimate, then trust your thermometer to tell you when its truly ready.