Flap Steak vs Outside Round — What's the Difference?
Quick Answer
Flap Steak (flap steak (sirloin flap)) and Outside Round (bottom round (outside round)) are not the same cut: Flap Steak is sirloin primal (Bottom sirloin, obliquus internus abdominis muscle); Outside Round is round primal (Outer thigh of the hindquarter).
Canonical entities: Flap Steak · Outside Round
Side-by-side
| flap steak | outside round | |
|---|---|---|
| Primal | sirloin | round |
| Muscle / location | Bottom sirloin, obliquus internus abdominis muscle | Outer thigh of the hindquarter |
| Character | A thin, coarse-grained steak from the bottom sirloin. The American name for what the French call bavette d'aloyau. Open grain absorbs marinades extremely well. Popular for fajitas, stir-fry, and carne asada. Often confused with skirt steak but from a different location entirely. | From the outer thigh (biceps femoris). Leaner and less tender than inside round. Used for roasts, rouladen, and ground beef. Often sold as bottom round roast or eye of round. |
Key differences
- Different primals: sirloin vs round.
- Texture and slicing: compare fibrous, grain-heavy cuts vs more tender steak-style muscles based on each cut’s description.
- Retail naming diverges by country—always map through a canonical cut when translating menus or labels.
When to use each
Flap Steak
Pick Flap Steak when you want its specific marbling/texture profile: A thin, coarse-grained steak from the bottom sirloin. The American name for what the French call bavette d'aloyau. Open grain absorbs marinades extremely well. Popular for fajitas, stir-fry, and carne asada. Often confused with skirt steak but from a different location entirely.
Outside Round
Pick Outside Round when its primal/muscle traits fit the dish: From the outer thigh (biceps femoris). Leaner and less tender than inside round. Used for roasts, rouladen, and ground beef. Often sold as bottom round roast or eye of round.
Flap Steak and Outside Round are different canonical muscles/primals: Flap Steak is sirloin (Bottom sirloin, obliquus internus abdominis muscle); Outside Round is round (Outer thigh of the hindquarter).
Choose based on tenderness, marbling, grain direction, and how you plan to cook (sear vs braise vs slice thin).
Read the full guides: flap steak (what-is) · outside round (what-is) · flap steak hub · outside round hub