Inside vs Outside Skirt Steak: A Butcher Explains the Cut Most People Get Wrong

The Skirt Steak Secret Restaurants Don't Want You to Know

Walk into any grocery store and pick up a package labeled "skirt steak." Nine times out of ten, you're holding an inside skirt steak. It'll make decent fajitas. It'll work for carne asada. But it's not what the best Tex-Mex restaurants and high-end steakhouses are using.

They're using the outside skirt steak — a thicker, more tender, better-marbled cut that most home cooks have never even seen at retail. There are only two per animal, and the restaurant industry buys them up before they ever reach a supermarket shelf.

After four decades behind the butcher counter, I've watched this knowledge gap persist. People think skirt steak is skirt steak. It's not. The difference between inside and outside skirt is as significant as the difference between chuck roast and chuck steak — same general area, completely different eating experience.

Anatomy: Where Each Cut Comes From

Both skirt steaks come from the diaphragm muscle of the steer, but they're separate muscles with different structures.

Outside Skirt Steak

The outside skirt is the costal portion of the diaphragm — the part attached to the ribs on the outside of the chest cavity. It sits between the 6th and 12th ribs, running along the outside of the plate primal. This is a well-exercised muscle that benefits from excellent blood flow, which contributes to its rich marbling.

A trimmed outside skirt steak typically measures 20 to 24 inches long, 3 to 4 inches wide, and ¾ to 1 inch thick. It weighs between 1 and 1.5 pounds. The thickness is what sets it apart — that extra quarter-inch makes a real difference when you're cooking over high heat.

Inside Skirt Steak

The inside skirt is the crural portion of the diaphragm — the part that sits inside the chest cavity, closer to the flank. It's attached to the transverse abdominal wall and runs deeper within the animal.

A trimmed inside skirt steak runs 20 to 24 inches long, 5 to 7 inches wide, but only ¼ to ½ inch thick. It weighs 1.5 to 2 pounds — heavier than the outside skirt because it's wider, but significantly thinner. That thinness is both its defining characteristic and its biggest challenge in the kitchen.

Side-by-Side Comparison: Width, Thickness, and Dimensions

Here's exactly how they stack up:

• Outside skirt width: 3-4 inches (narrow and thick)
• Inside skirt width: 5-7 inches (wide and thin)
• Outside skirt thickness: ¾ to 1 inch
• Inside skirt thickness: ¼ to ½ inch
• Outside skirt weight: 1-1.5 lbs per piece
• Inside skirt weight: 1.5-2 lbs per piece
• Outside skirt per animal: 2
• Inside skirt per animal: 2

The easiest way to remember: the outside skirt is narrow and thick, the inside skirt is wide and thin. If you're looking at a piece of skirt steak wider than your hand, it's almost certainly an inside skirt.

Marbling and Fat Content

This is where the outside skirt truly separates itself. The costal diaphragm muscle has significantly more intramuscular fat — visible marbling that melts during cooking and delivers that rich, beefy flavor people associate with premium steak.

The outside skirt typically grades higher in marbling than the inside skirt from the same animal. A Choice-grade steer might produce an outside skirt with marbling approaching Prime levels, while the inside skirt from the same animal stays firmly in the Select-to-Choice range.

There's also a difference in the surrounding fat. The outside skirt comes with a thick membrane on one side (the peritoneum) that needs to be removed, plus a substantial fat cap. A good butcher trims both, leaving just the well-marbled muscle. The inside skirt has a thinner membrane and less external fat, which means less trimming but also less protection during cooking.

Texture and Grain Structure

Both cuts have prominent, coarse grain — those long parallel muscle fibers that make slicing against the grain absolutely critical. But the texture differs in important ways.

Outside skirt: The fibers are thick and loosely packed with fat running between them. When you slice against the grain, each piece has visible marbling threads that have rendered during cooking. The texture is tender but with satisfying chew — what butchers call "good tooth." It's the steak that makes you want to keep eating.

Inside skirt: The fibers are tighter and more densely packed with less intramuscular fat between them. Sliced against the grain, it's chewier and can feel tougher, especially if overcooked even slightly. The thinner profile means the inside skirt goes from perfectly done to overdone in about 30 seconds — a small margin of error that trips up a lot of cooks.

If you've ever made skirt steak at home and thought "this is good but not as tender as the restaurant version," the difference was probably the cut, not your technique. Restaurants use outside skirt. You were cooking inside skirt.

Flavor Profile

Both skirt steaks deliver intense, robust beef flavor — more than you'll get from most other steaks. The diaphragm is a hard-working muscle with excellent blood supply, which translates to deep, mineral-rich flavor that stands up to bold seasonings and high-heat cooking.

The outside skirt has a richer, more buttery dimension thanks to its higher fat content. The marbling creates pockets of rendered fat that coat your palate between bites. It's the kind of flavor that makes a simple squeeze of lime and a sprinkle of salt feel like a complete meal.

The inside skirt has a cleaner, more direct beef flavor — intense but leaner. It benefits more from marinades because the tighter grain structure absorbs liquid well, and the leaner profile means it can use the added fat and acid from a good marinade. Where the outside skirt is naturally rich, the inside skirt is a canvas that rewards good marination.

Why Restaurants Get All the Outside Skirt

Here's the supply chain reality that explains why you can't find outside skirt at Costco:

The USDA requires that outside skirt steaks be removed from the carcass during the initial fabrication process. They come off early, get trimmed, and enter a separate supply chain from the rest of the beef primals. Meat packers know exactly what they have, and the restaurant and export market absorbs nearly all of it.

Mexican and Japanese buyers pay premium prices for outside skirt steaks. In Mexico, it's the gold standard for arrachera — the original fajita cut. In Japan, it's prized for harami (ハラミ), one of the most popular cuts in yakiniku restaurants. Domestic restaurant chains and Tex-Mex operations snap up whatever's left.

By the time the supply chain reaches retail, there's almost no outside skirt left. Grocery stores stock inside skirt because that's what's available — and most consumers don't know the difference, so there's no demand pressure to change the distribution.

If you want outside skirt at retail, your best bet is a dedicated butcher shop, a specialty meat purveyor like The Meatery, or a Mexican carnicería that has relationships with meat packers.

How to Tell Them Apart at the Store

Retailers aren't required to specify "inside" or "outside" on the label — they can just say "beef skirt steak." But you can identify them visually:

• If it's wide and thin (wider than 4 inches, thinner than ½ inch): Inside skirt
• If it's narrow and thick (3-4 inches wide, ¾ inch thick or more): Outside skirt
• If it has a uniform, smooth surface: Likely inside skirt
• If it has a slightly rougher texture with visible fat marbling: Likely outside skirt
• If it's at a regular grocery store: Almost certainly inside skirt
• If it costs noticeably more per pound: Might be outside skirt (but verify visually)

The thickness test is the most reliable. Pick it up and look at the edge. If you can practically see through it, that's inside skirt. If it has real substance — close to an inch thick — you've found the good stuff.

Cooking Inside Skirt Steak

Inside skirt requires a different approach than its thicker counterpart. The key challenge is getting a hard sear without overcooking the interior, and with only ¼ to ½ inch of thickness, you have almost no buffer.

Best methods for inside skirt:

• Screaming hot cast iron or carbon steel — Preheat until the pan is smoking. Sear 60-90 seconds per side, no more. You want a crust on the surface while the center stays medium-rare.
• Direct flame on a grill — Maximum heat, grates as close to the coals as possible. 1-2 minutes per side. Pull at 125°F internal — carryover will take it to 130°F.
• Wok or plancha — Extremely high heat with a thin film of high-smoke-point oil. This is how taquería cooks handle inside skirt: fast, aggressive heat, quick rest, chop.

Critical tips:

• Always pat the surface completely dry before cooking — moisture is the enemy of sear, and thin cuts can't afford to steam
• Marinate for 2-4 hours (the tighter grain absorbs flavors well)
• Rest for only 3-5 minutes — thinner cuts cool fast
• Slice against the grain into ¼-inch strips at a sharp bias
• Don't go past medium-rare — inside skirt toughens dramatically above 140°F

Cooking Outside Skirt Steak

The outside skirt is more forgiving and more versatile. That extra thickness gives you a real medium-rare zone to work with — you can develop a serious crust while keeping the interior pink and juicy.

Best methods for outside skirt:

• High-heat grill — The classic. Direct heat, 3-4 minutes per side for medium-rare. The fat renders and drips onto the coals, creating those small flare-ups that add smoky char.
• Cast iron sear — Smoking hot, 2-3 minutes per side. The thickness means you get a pronounced crust-to-center gradient that's incredibly satisfying.
• Reverse sear — Yes, you can reverse sear an outside skirt. Start in a 250°F oven until 115°F internal, then blast it in a ripping hot pan. This works because the outside skirt is thick enough to benefit from edge-to-edge even cooking.

Critical tips:

• Season generously with coarse salt 30-45 minutes before cooking
• Marinating is optional — the natural marbling provides plenty of flavor and moisture
• Rest 5-7 minutes before slicing
• Slice against the grain (the grain runs across the short width)
• Medium-rare to medium is ideal — the higher fat content means medium still tastes great

Best Uses for Each Cut

Inside Skirt Steak Excels At:

• Fajitas — The thinness means it cooks fast and chops easily for taco-sized pieces
• Stir-fry — Slices thin and cooks in seconds over high heat
• Carne asada (taquería-style) — Thin, fast-cooked, chopped on a board
• Marinaded applications — The lean, tight grain soaks up flavor beautifully
• Budget-friendly meals — Typically $2-4 less per pound than outside skirt

Outside Skirt Steak Excels At:

• Restaurant-quality fajitas — The tender, juicy slices that make you wonder what the restaurant is doing differently
• Standalone steak — Thick enough to serve as a plated steak with just salt, pepper, and lime
• Korean BBQ (galbi) — The marbling makes it ideal for tabletop grilling
• Arrachera — Traditional Mexican preparation that showcases the outside skirt's superiority
• Yakiniku — Japanese grilled meat preparation where the cut is called harami

Price Comparison

Outside skirt steak commands a premium, and the gap has widened in recent years as demand from restaurants, export markets, and educated home cooks has increased.

• Inside skirt steak: $8-14 per pound at retail (2026 prices)
• Outside skirt steak: $14-22 per pound at retail, when available
• Outside skirt at wholesale/restaurant: $10-16 per pound

That's a significant premium, but remember: the outside skirt has a higher yield after trimming and delivers a noticeably better eating experience. Cost per satisfying bite, the outside skirt often provides better value than its sticker price suggests.

For premium outside skirt steak from quality-verified sources, check The Meatery's beef collection.

Common Mistakes with Both Cuts

After watching thousands of customers cook skirt steak over the years, here are the mistakes I see most often:

• Cutting with the grain — This turns any skirt steak into shoe leather. The grain on skirt steak is obvious and runs across the width. Always slice perpendicular to those fibers.
• Not enough heat — Skirt steak needs the highest heat you can generate. If your pan isn't smoking, it's not hot enough. Medium heat will steam the meat instead of searing it, and you'll end up with a gray, tough steak.
• Overcooking inside skirt — The margin between perfect and ruined is about 30 seconds with inside skirt. Use a timer. Pull it early. It will carry over.
• Skipping the rest — Even a 3-minute rest allows the fibers to relax and retain juice. Cut immediately and you'll lose a tablespoon of liquid per steak.
• Over-marinating — More than 4 hours in an acid-based marinade starts breaking down the surface texture. The steak gets mushy on the outside and tough on the inside. Two to four hours is the sweet spot for both cuts.
• Treating them identically — The biggest mistake of all. These are different cuts that require different timing, different heat management, and different expectations. Adapt your technique to the specific cut in your hand.

The Butcher's Verdict

If I could only have one skirt steak for the rest of my life, it's the outside skirt, no contest. The thickness, the marbling, the tenderness — it's one of the most underrated cuts in the entire animal. When you find one at a good butcher shop, buy it. Buy two. They freeze beautifully.

But the inside skirt is nothing to dismiss. It's a legitimate cut that, when treated with the respect it deserves — screaming hot heat, minimal cooking time, razor-sharp knife against the grain — delivers excellent results. It's just less forgiving than the outside skirt, so your technique matters more.

The real tragedy isn't that inside skirt exists. It's that most people cook it without knowing what it is, compare it unfairly to a restaurant experience built on outside skirt, and conclude they can't cook steak. You can cook steak. You just need to know which steak you're cooking.

For those who want to experience the real difference, The Meatery sources premium skirt steaks from top-tier suppliers — including the outside skirt that's nearly impossible to find at retail. Taste the difference a cut makes, and you'll never look at "skirt steak" the same way again.