Inside Skirt vs Sirloin Cap — What's the Difference?
Quick Answer
Inside Skirt (inside skirt steak) and Sirloin Cap (sirloin cap) are not the same cut: Inside Skirt is plate primal (Transversus abdominis muscle — the inner diaphragm muscle); Sirloin Cap is sirloin primal (top sirloin cap (coulotte)).
Canonical entities: Inside Skirt · Sirloin Cap
Side-by-side
| inside skirt | sirloin cap | |
|---|---|---|
| Primal | plate | sirloin |
| Muscle / location | Transversus abdominis muscle — the inner diaphragm muscle | top sirloin cap (coulotte) |
| Character | The 'other' skirt steak. Thinner, wider, and slightly tougher than the outside skirt (which is the standard 'skirt steak'). Most restaurant fajitas use inside skirt because the outside skirt is exported or sold at premium. Requires high heat, fast cooking, and slicing against the grain. | Triangular cap on the top sirloin; prized as picanha in Brazil. |
Key differences
- Different primals: plate vs sirloin.
- 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
Inside Skirt
Pick Inside Skirt when you want its specific marbling/texture profile: The 'other' skirt steak. Thinner, wider, and slightly tougher than the outside skirt (which is the standard 'skirt steak'). Most restaurant fajitas use inside skirt because the outside skirt is exported or sold at premium. Requires high heat, fast cooking, and slicing against the grain.
Sirloin Cap
Pick Sirloin Cap when its primal/muscle traits fit the dish: Triangular cap on the top sirloin; prized as picanha in Brazil.
Inside Skirt and Sirloin Cap are different canonical muscles/primals: Inside Skirt is plate (Transversus abdominis muscle — the inner diaphragm muscle); Sirloin Cap is sirloin (top sirloin cap (coulotte)).
Choose based on tenderness, marbling, grain direction, and how you plan to cook (sear vs braise vs slice thin).
Read the full guides: inside skirt (what-is) · sirloin cap (what-is) · inside skirt hub · sirloin cap hub