Flap Steak vs Top Sirloin — What's the Difference?
Quick Answer
Flap Steak (flap steak (sirloin flap)) and Top Sirloin (top sirloin) are not the same cut: Flap Steak is sirloin primal (Bottom sirloin, obliquus internus abdominis muscle); Top Sirloin is sirloin primal (Upper hip, above the sirloin cap (coulotte) and behind the short loin).
Canonical entities: Flap Steak · Top Sirloin
Side-by-side
| flap steak | top sirloin | |
|---|---|---|
| Primal | sirloin | sirloin |
| Muscle / location | Bottom sirloin, obliquus internus abdominis muscle | Upper hip, above the sirloin cap (coulotte) and behind the short loin |
| 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. | A large, lean cut from the hip section. The top sirloin butt (NAMP 184) is the main muscle group. Versatile — grilled as steaks, roasted whole, or cut into kabobs. Moderate tenderness with good beefy flavor. Not to be confused with sirloin cap (coulotte/picanha) which sits on top of it. |
Key differences
- 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.
Top Sirloin
Pick Top Sirloin when its primal/muscle traits fit the dish: A large, lean cut from the hip section. The top sirloin butt (NAMP 184) is the main muscle group. Versatile — grilled as steaks, roasted whole, or cut into kabobs. Moderate tenderness with good beefy flavor. Not to be confused with sirloin cap (coulotte/picanha) which sits on top of it.
Flap Steak and Top Sirloin are different canonical muscles/primals: Flap Steak is sirloin (Bottom sirloin, obliquus internus abdominis muscle); Top Sirloin is sirloin (Upper hip, above the sirloin cap (coulotte) and behind the short loin).
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) · top sirloin (what-is) · flap steak hub · top sirloin hub