Beef sirloin is one of the two major subprimals of the beef loin primal cut, which runs from the 13th rib to the end of the hip bone. Butchers separate the sirloin into the top butt and the bottom butt; lean but flavorful top sirloin steaks are an affordable option for the grill while a tri-tip cut from the bottom makes a good choice for roasting.
What Is Beef Sirloin?
Of the two loin subprimals, the sirloin sits farther back toward the rear leg, where the muscles get more exercise. The meat from this section can be tougher than cuts from the front part of the loin, called the short loin. The sirloin is separated from the short loin at the front tip of the hip bone by a straight cut through the seventh lumbar vertebra.
The sirloin is almost always broken down into two boneless wholesale cuts: the top sirloin butt and bottom sirloin butt. This is done by cutting along the natural seam between the gluteus medius, the primary muscle of the top sirloin, and the knuckle, a group of three muscles (the rectus femoris, vastus lateralis, and vastus medialis) sometimes called the sirloin tip.
Top Sirloin Butt
The top sirloin butt (also known as top butt or sirloin butt) generally gets made into boneless steaks but it can be trimmed to varying degrees. For instance, the top butt includes a triangular muscle called the biceps femoris, or sirloin cap, which usually gets pulled off and cut into steaks called cap steaks or coulotte steaks.
Top sirloin steaks and top sirloin filets make economical choices for the grill that still come close in enjoyment to the more expensive short loin and rib cuts such as the New York strip and rib-eye. Like the corresponding steaks, roasts from this section offer a good balance of flavor and value.
Bottom Sirloin Butt
With bottom sirloin, which sits closer to the cow's rear legs, the muscles get tougher. Cuts from the bottom sirloin tend to be used for roasts, and it provides a lot of ground beef and stew meat, too.
Probably the most popular bottom sirloin roast is the tri-tip, which is made from a coarse-grained triangular muscle called the tensor fasciae latae. Tri-tip is fairly lean, although it does have a layer of fat on the outside that can be desirable for slow cooking.
The sirloin tip (or knuckle) is another roast from the bottom sirloin, and it happens to be situated precisely at the spot where the loin is separated from the round primal. If a carcass is butchered according to specifications, about three-fourths of the knuckle will end up in the round section, and the remaining quarter of it in the loin. What often happens instead is that the whole knuckle is removed from the carcass and sold as sirloin tip.
Finally, the sirloin flap is a thin muscle called the obliquus abdominis interni, located beside the tri-tip, where the loin curves down toward the belly or flank.
Tenderloin or Butt Tender
The sirloin sometimes contains something called the butt tender, or the rear portion of the tenderloin, which is the most tender muscle on the beef carcass. Since it's at the wide end and has a fairly uniform thickness, the butt tender is easy to make into steaks. It can also be trimmed and sold as a whole roast. However, the tenderloin is often removed from the loin and either sold whole or as tenderloin steaks (i.e. filet mignon) or roasts (Chateaubriand).
How to Cook Beef Sirloin
Top sirloin steaks are generally suitable for high-heat grilling, but be careful not to overcook them since the meat can start to turn tough and dry at temperatures beyond 145 F, or medium doneness. Marinating sirloin steaks adds flavor and moisture, but contrary to popular belief, it doesn't have the power to tenderize the meat.
Tri-tip can be grilled over indirect heat or smoked/oven roasted at a low temperature (i.e. 225 F). Some cooks like to season tri-tip, and since the meat is so lean, it does benefit from a little extra flavor. It also benefits from marinating. Slice tri-tip against the grain when you serve it to make it easier to chew.
What Does Beef Sirloin Taste Like?
Cuts from the sirloin tend to be flavorful but potentially chewy since they're on the leaner side. Most need to be cooked hot and fast or low and slow to prevent toughness. The sirloin flap is very similar to flank steak—coarse-grained muscles with lots of marbling and deep beef flavor.
Beef Sirloin Recipes
Among the more common cuts available, sirloin steaks are also some of the most versatile.
Where to Buy Beef Sirloin
Your local grocery store should carry most cuts from the sirloin as it's a more economical subprimal that yields larger cuts suited to a family. Choose steaks and roasts with the most marbling and the most even thickness for ease of cooking.
Storing Beef Sirloin
Beef sirloin cuts still in the store packaging stay good for up to three days in the refrigerator. Wrap individual steaks or roasts tightly in plastic wrap or specialty freezer paper and store them in the freezer for up to three months. For best results or longer-term storage, use a vacuum sealer.
Put leftover cooked beef in an airtight container in the refrigerator and consume it within three days.
Nutrition and Benefits of Beef Sirloin
Sirloin cuts from the top butt contain about 175 calories per 3.5-ounce portion and 5 grams of fat. They also deliver 30.8 grams of protein, plus the B vitamins responsible for red blood cell health and minerals such as zinc, phosphorous, and selenium.
Roasts from the bottom portion of the sirloin deliver about 182 calories, 26.5 grams of protein, and 8.3 grams of fat, plus the same beneficial vitamins and minerals.
US Department of Agriculture. FoodData Central. Beef, top sirloin, steak, separable lean only, trimmed to 0" fat, select, cooked, broiled. Updated April 1, 2019.
US Department of Agriculture. FoodData Central. Beef, loin, bottom sirloin butt, tri-tip roast, separable lean only, trimmed to 0" fat, all grades, cooked, roasted. Updated April 1, 2019.