What's In-N-Out's Secret Sauce Really Made Of?

In-N-Out burger, the west coast fast food chain, is famous for a lot of things, from its not-so-secret secret menu to its fresh beef burgers and its legendary thick shakes and loaded fries (and its regular fries, which some people find quite disappointing). From their burgers to their Animal-Style fries, the fast food chain's famed burger spread is what gives these items their signature taste, and it got us wondering — what's In-N-Out's secret sauce really made of? 

The sauce is creamy, tangy, salty, and slightly sweet, bringing to mind Thousand Island dressing. But it's not quite that simple. We wanted to find out what's really in the spread, and how you can make it at home.

The truth about In-N-Out's secret sauce

In-N-Out doesn't list the ingredients for its spread on their website (via In-N-Out), but there are some burger sleuths who believe they've uncovered the secret formula. 

J. Kenji Lopez-Alt, chef and food scientist, thinks he's figured it out (via Serious Eats). Lopez-Alt broke down the formula for making the spread, first tasting it alone, straight from the packet, and then recreating it. According to him, the spread is indeed a Thousand Island-style sauce made from ketchup, mayonnaise, and sweet pickle relish. 

After breaking down the sauce by calculating its parts based on caloric makeup, and even by straining out and weighing the relish pieces, Lopez-Alt deduced that the In-N-Out secret sauce is made by combining 2 tablespoons plus 2 teaspoons mayonnaise, 1 tablespoon ketchup, and 2 teaspoons of pickle relish. A splash of vinegar and pinch of sugar balances out the flavors, and voila — you have In-N-Out burger spread you can make at home. 

Is it identical to the real thing? Unless In-N-Out ever releases their official ingredient list or recipe, we'll never know. But until then, this is about as close to the real deal as you can get. 

Does In-N-Out Animal Style use burger spread?

In-N-Out's burger spread comes by default on all of its burgers, but there's one area where it really shines: in the chain's "Animal Style" menu offerings. 

An Animal Style burger comes with the burger of your choice, but with some upgrades. The burger patties are smothered in mustard and grilled, which gives them a caramelized, tangy exterior. Then, they're put on a bun with lettuce, tomato, pickle, grilled onions, and the crowning glory: extra burger spread. 

Animal Style fries feature an abundance of burger spread too (via Serious Eats). We recommend ordering Animal Style fries "well done," so they're cooked longer, meaning your fries get crispy and golden brown. 

That means they'll be better able to stand up to the load of toppings: melted American cheese, grilled onions, and a mega-helping of creamy burger spread. 

If you want burger spread on any other menu items, or if you just want extra, you can also get packets of the stuff to squeeze onto your food. Even better? Ordering extra burger spread packets is free (via Hack the Menu).  

Is In-N-Out's burger spread Thousand Island dressing?

Thanks to the similarities in their color, flavor, and texture, people sometimes think that In-N-Out's burger spread is Thousand Island dressing, but it's not. Traditionally, Thousand Island dressing does have some of the same ingredients as In-N-Out's burger sauce — mayonnaise, ketchup, and pickle relish — but real Thousand Island dressing is a little more complicated. The original recipe for Thousand Island was also blended with a hard-boiled egg to help thicken it, and it was seasoned with a splash of Worcestershire sauce (via NPR).

In-N-Out's burger spread, on the other hand, simply contains mayo, ketchup, sweet pickle relish, and a splash of vinegar. It's similar, and if you need a copycat In-N-Out burger spread in a pinch Thousand Island dressing might do, but it's not quite the real thing. 

Do McDonald's and In-N-Out have the same 'special sauce?'

In-N-Out isn't the only burger chain that has a signature sauce that it puts on its sandwiches. McDonald's is famous for its Big Mac sauce, which is served on the sandwich of the same name (via McDonald's). McDonald's "special sauce" does have a similar texture and flavor to In-N-Out's burger spread. 

A closer look at the ingredient list shows one major difference between the two, though: while McDonald's, like In-N-Out, includes sweet pickle relish and mayonnaise in their secret sauce, McDonald's doesn't include ketchup, or any tomato products at all (via The Sun). Without the ketchup, the Big Mac secret sauce is a little less sweet and a little less tangy than In-N-Out's burger spread.

The McDonald's Big Mac also includes a few more spices, including onion powder and mustard seed, which gives it a more savory flavor.