Flap Steak vs Inside Round — What's the Difference?
Quick Answer
Flap Steak (flap steak (sirloin flap)) and Inside Round (top round (inside round)) are not the same cut: Flap Steak is sirloin primal (Bottom sirloin, obliquus internus abdominis muscle); Inside Round is round primal (Inner thigh of the hindquarter).
Canonical entities: Flap Steak · Inside Round
Side-by-side
| flap steak | inside round | |
|---|---|---|
| Primal | sirloin | round |
| Muscle / location | Bottom sirloin, obliquus internus abdominis muscle | Inner 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. | A large, lean cut from the inner thigh (adductor and semimembranosus muscles). Sold as top round steaks, London broil, or roasts. Lean but can be tough — best sliced thin or braised. |
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.
Inside Round
Pick Inside Round when its primal/muscle traits fit the dish: A large, lean cut from the inner thigh (adductor and semimembranosus muscles). Sold as top round steaks, London broil, or roasts. Lean but can be tough — best sliced thin or braised.
Flap Steak and Inside Round are different canonical muscles/primals: Flap Steak is sirloin (Bottom sirloin, obliquus internus abdominis muscle); Inside Round is round (Inner 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) · inside round (what-is) · flap steak hub · inside round hub