In-N-Out Burger Sauce Vs ShackSauce: What's The Difference?

Much like politics, revealing your favorite place to grab a fast food burger can be a dicey topic in polite conversation. This is especially true when you have to choose between two of the biggest players in the game: Shake Shack and In-N-Out.

Shake Shack, which began as a New York City hot dog cart, produces one of the city's most popular smash burgers, celebrated for its balanced seasoning and pillowy potato bun. On the other hand, fans of the California-based chain frequently praise the freshness of In-N-Out's ingredients. As every fast food fan knows, though, a restaurant's burger is only as good as its signature sauce.

Both restaurants top their burgers with Thousand Island-style sauces. These are made from a combination of mayonnaise, ketchup, and sweet relish, among other ingredients. Despite their commonalities, however, the two sauces notably differ in texture and flavor, incorporating varying degrees of sweetness, tanginess, and spice. Although both chains keep their signature sauce recipes under lock and key, we can do our best to extrapolate the differences between them.

Slathered on each of In-N-Out's burgers is a generous helping of the restaurant's top-secret spread. You can even get the sauce dumped on your fries if you order them "Animal Style" — a variation from In-N-Out's secret menu that includes the signature spread, as well as cheese and grilled onions.

Much like Thousand Island dressing, In-N-Out's Burger Spread has a creamy mayonnaise base, a tomatoey element that gives the sauce its signature pink hue, and sweet pickle relish, which supplies not just texture but also acidity and sweetness, two of the sauce's dominating traits. Over the years, the burger chain and its employees have remained tight-lipped about the sauce's contents. The only information offered on the company's website is a note that the sauce's recipe has remained unchanged since 1948 — the same year the first In-N-Out burger stand opened in Baldwin Park, California. Nevertheless, most copycat In-N-Out Burger Sauce recipes suggest it's made with mayo, ketchup, sweet pickle relish, and white vinegar.

With a bit of detective work and some food science knowledge, chef and food writer J. Kenzie Lopez-Alt was even able to approximate the proportions of the ingredients in the sauce. By his estimation, In-N-Out sauce is 62% mayonnaise, 23% ketchup, and 15% sweet pickle relish, with an extra splash of vinegar for good measure (via Serious Eats).

While ShackSauce contains similar components, it has a distinctly thicker texture than In-N-Out's spread, which some fans say keeps the sauce in place and adds to the enjoyment of the ShackBurger. It's also significantly tangier with a hint of smokiness and a touch of heat, and it's noticeably less sweet than its competitor.

Although ShackSauce still retains some semblance of mystery, Randy Garutti and Mark Rosati — Shake Shack's CEO and Culinary Director, respectively — are much less reluctant to share their secrets than In-N-Out. In their 2017 cookbook "Shake Shack: Recipes & Stories," the pair cheekily suggested that they wouldn't give out the exact recipe but that they would get readers "close enough." Per Popsugar, the recipe calls for mayonnaise, Dijon mustard, ketchup, cayenne pepper, and dill pickle brine.

Former Popsugar Director and Producer Nicole Iizuka, who claims to have once worked at Shake Shack, alleges ShakeSauce also used to contain pickles and chipotle peppers, the latter of which reportedly add to the heat and smokiness of the final product. To this point, J. Kenzi Lopez-Alt claims a Shake Shack manager told him the secret to ShakeSauce isn't relish, but blended dill pickles — the same ones that top off the restaurant's famous burgers (via Serious Eats). Regardless, most copycat Shake Shack ShackBurger recipes tend to just use pickle juice in the sauce instead.