How Are McDonald's Big Mac & Big Arch Sauces Different?

On March 3, McDonald's unleashed its Big Arch burger onto the American public. The burger had already proven to be a hit in international markets and was recently made a permanent part of the menu at restaurants in Ireland and the U.K. Naturally, consumers are curious about this item and its resemblance to the tried and true Big Mac, a classic at the chain. Both burgers come adorned with a special sauce, and we're here to guide you through the differences between each. 

While these condiments have a lot in common, Big Arch sauce contains ingredients that push the flavor closer to ketchup than its predecessor. In the states, the Big Arch will only be available for a limited time, and the transient nature of this fast-food offering has created tons of buzz. Well, that and McDonald's CEO Chris Kempczinski's viral clip (via Instagram), which showed the executive taking a tiny baby bite of the larger-than-life burger. The launch of the Big Arch is one of the many major changes that McDonald's is making in 2026, along with new kitchen tech and enhanced mobile ordering. 

The Big Mac, which was invented by a McDonald's franchisee in Pittsburgh, Pennsylvania, has been part of the restaurant's menu since 1968. Consisting of two beef patties, American cheese, pickles, lettuce, and diced onions, the Big Mac would be far less impressive without its namesake sauce. While it's often compared to Thousand Island dressing, the truth about McDonald's Big Mac sauce is that it contains no ketchup, which is typically found in the dressing. In fact, the lack of ketchup and other tomato-based ingredients is one of the primary differences between this sauce and the newly introduced Big Arch sauce. 

According to the ingredient listing provided by McDonald's, Big Mac sauce contains sweet relish, vinegar, onion powder, paprika extracts, sugar, and salt, among other ingredients. The resulting flavor features savory, acidic, and subtly sweet notes, which nicely contrasts the richer, meatier flavor profile of the burger. Big Mac sauce has undergone a few iterations since its debut, but the original 1968 recipe was restored in 2004. Keep in mind that McDonald's is a bit stingy when it comes to its special sauce, as it's usually only available on the Big Mac. Though sauce cups containing the condiment were available for a limited time, the website doesn't list the sauce as an option among its other selections. This explains the proliferation of Big Mac sauce copycat recipes, which give fast-food fans the tools to whip up the zesty condiment on their own.

The Big Arch is a substantial burger, to be sure. From the massive sesame and poppy seed bun to the dual ¼ pound beef patties, this hefty two-hander is adorned with white cheddar cheese, pickles, lettuce, and two types of onions (crispy fried onions and slivered raw onions). As for the Big Arch sauce, it forges its own ingredient path by featuring tomato paste as the third ingredient, and mustard, both of which are absent in the Big Mac sauce. Big Arch sauce also leaves out the sweet relish. 

When it comes to the flavor of McDonald's latest condiment, the inclusion of tomato paste calls to mind ketchup. The mustard in the recipe offers tanginess and acidity, but the sweetness gets dialed back extensively. If the Big Arch release is making you feel déjà vu, you're not imagining things. The burger has links to the Arch Deluxe, also known as one of the biggest flops in McDonald's history. 

Introduced in 1996, the Arch Deluxe was supposed to be a more sophisticated burger to match adult flavor preferences. Instead, consumers expressed dissatisfaction that they were expected to pay more for a burger that had many similarities to cheaper items at the chain. Customers should expect a similar sticker shock with the Big Arch. According to prices at a local McDonald's, the Big Mac costs $5.89, while the Big Arch costs $9.39, which could deter value-seeking consumers from ordering the burger.