Sirloin roast in the oven requires resting time after cooking, which affects when you should actually start checking for doneness. That single detail changes the answer to how long to cook a sirloin roast in the oven, because the meat keeps cooking while it sits.
Most home cooks pull the roast too late and end up with dry slices. The fix is simple: cook to a target internal temperature, then let the roast rest. Below you’ll find exact times, temps, and a step-by-step method that works every time.
How Long To Cook A Sirloin Roast In The Oven
The short answer depends on weight and your desired doneness. As a general rule, plan on 15 to 20 minutes per pound at 350°F (175°C) for medium-rare. A 4-pound roast lands around 60 to 80 minutes, plus 15 to 20 minutes of resting.
Always use a meat thermometer. Time gives you a rough plan, but temperature gives you the real answer.
Time And Temperature Chart By Doneness
Use these internal temperatures for the center of the roast. Pull the meat 5 to 10 degrees below your target, since carryover cooking raises it during the rest.
- Rare: 120°F to 125°F final, pull at 115°F to 120°F
- Medium-rare: 130°F to 135°F final, pull at 125°F to 130°F
- Medium: 140°F to 145°F final, pull at 135°F to 140°F
- Medium-well: 150°F to 155°F final, pull at 145°F to 150°F
- Well done: 160°F and up final, pull at 155°F
At 350°F, expect roughly 15 to 20 minutes per pound for medium-rare. A 3-pound roast needs about 45 to 60 minutes. A 5-pound roast needs about 75 to 100 minutes. Ovens run hot or cold, so check early and check often.
Why Resting Time Changes Your Start Time
Resting is not optional. During the rest, juices redistribute and the internal temp climbs another 5 to 10 degrees. If you pull at your final target, you’ll overshoot and dry out the meat.
This is why you should start checking for doneness 10 to 15 minutes before your calculated time. Then add the rest period to your total timeline. If dinner is at 6 p.m., a 4-pound roast needs to come out around 4:45 p.m. to rest, carve, and serve on time.
Step-By-Step Method For A Perfect Sirloin Roast
Step 1: Prep And Season The Meat
Take the roast out of the fridge 30 to 60 minutes before cooking. A room-temp roast cooks more evenly. Pat it dry with paper towels so the surface browns well.
Season generously with salt and black pepper. For extra flavor, rub in garlic powder, rosemary, or thyme. Let it sit while the oven preheats to 350°F.
Step 2: Sear For A Better Crust
Searing is optional but adds a deep brown crust. Heat a heavy skillet or Dutch oven over high heat with a tablespoon of oil. Sear the roast on all sides, about 2 to 3 minutes per side.
If you skip searing, that’s fine. You can also broil the roast for the last 5 minutes to brown the top.
Step 3: Roast At 350°F
Place the roast fat side up on a rack in a roasting pan. Insert a meat thermometer into the thickest part, avoiding bone and fat. Roast uncovered.
Use this simple timing guide:
- 3-pound roast: start checking at 45 minutes
- 4-pound roast: start checking at 60 minutes
- 5-pound roast: start checking at 75 minutes
- 6-pound roast: start checking at 90 minutes
Check the temperature every 10 minutes after that first reading. Do not rely on time alone.
Step 4: Rest The Roast
When the thermometer reads 5 to 10 degrees below your target, take the roast out. Tent it loosely with foil. Do not wrap it tight, or the crust steams and softens.
Let it rest 15 to 20 minutes for a 3 to 4 pound roast. For a 5 to 6 pound roast, rest 20 to 30 minutes. The temp will rise during this window.
Step 5: Carve Against The Grain
Find the direction of the muscle fibers, then slice across them. This shortens the fibers and makes each bite tender. Cut slices about 1/4 to 1/2 inch thick.
Let any juices on the cutting board rest a minute, then spoon them over the slices.
Common Mistakes That Ruin Sirloin Roast
- Cooking by time only, without a thermometer
- Skipping the rest and slicing right away
- Roasting at too high a temp, which browns outside before the center cooks
- Not letting the meat sit at room temp before roasting
- Cutting with the grain instead of against it
Each of these leads to dry, tough slices. Fix them and your roast turns out juicy and tender.
Tips For Different Oven Types And Altitudes
Convection Ovens
Convection ovens cook faster and browner. Lower the temp to 325°F and cut the time by about 25 percent. Start checking even earlier than the chart suggests.
High Altitude
At high altitude, moisture evaporates faster and meat can dry out. Add 10 to 15 minutes per pound and keep a close eye on the thermometer. You may also want to add a half cup of water or broth to the pan.
Bone-In Versus Boneless
Bone-in roasts take slightly longer and have more flavor. Add about 5 minutes per pound to your estimate. Boneless roasts cook quicker and are easier to carve.
How To Know When Your Sirloin Roast Is Done
Use an instant-read thermometer. Insert it into the center of the thickest part, not touching bone or fat. Wait 10 seconds for a stable reading.
If you don’t have a thermometer, press the meat. A rare roast feels soft and springy. Medium feels firmer with some give. Well done feels stiff.
The thermometer is far more reliable. It costs a few dollars and saves an expensive roast.
Making Gravy From The Pan Drippings
Pour the drippings into a saucepan, leaving the fat behind. Add a cup of beef broth and bring to a simmer. Whisk in a tablespoon of flour mixed with cold water to thicken.
Simmer 3 to 5 minutes, then season with salt and pepper. Pour over sliced roast or serve on the side.
Final Timing Summary
For a 4-pound sirloin roast at 350°F, plan on about 60 to 80 minutes of cooking plus 15 to 20 minutes of resting. Total time from oven to table is roughly 1 hour 45 minutes.
Pull the roast 5 to 10 degrees before your target temp. Rest it, then carve against the grain. Follow these steps and you’ll get a juicy, tender roast every single time.