Flap Steak vs Skirt — What's the Difference?
Quick Answer
Flap Steak (flap steak (sirloin flap)) and Skirt (skirt steak) are not the same cut: Flap Steak is sirloin primal (Bottom sirloin, obliquus internus abdominis muscle); Skirt is plate primal (diaphragm (inside/outside skirt varies by spec)).
Canonical entities: Flap Steak · Skirt
Side-by-side
| flap steak | skirt | |
|---|---|---|
| Primal | sirloin | plate |
| Muscle / location | Bottom sirloin, obliquus internus abdominis muscle | diaphragm (inside/outside skirt varies by spec) |
| 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. | Plate primal diaphragm muscle; very beefy, used for fajitas and grilling. |
Key differences
- Different primals: sirloin vs plate.
- 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.
Skirt
Pick Skirt when its primal/muscle traits fit the dish: Plate primal diaphragm muscle; very beefy, used for fajitas and grilling.
Flap Steak and Skirt are different canonical muscles/primals: Flap Steak is sirloin (Bottom sirloin, obliquus internus abdominis muscle); Skirt is plate (diaphragm (inside/outside skirt varies by spec)).
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) · skirt (what-is) · flap steak hub · skirt hub