For as long as it's been around, the Bic Mac has only been available in one size. The moniker said it all: it was THE Big Mac. There was no Small Mac, there was no Biggest Mac, and we were content with this one-size-fits-all approach to burgers.Well, folks, that's about to change.According to FoodBeast , McDonald's will be releasing the Big Mac in two new sizes. The classic fast-food burger will soon become the middle child with the debut of the Mac Jr. and Grand Mac. The Mac Jr. is a single-layered version of the Big Mac. (In case you, like most millennials , haven't tried a Big Mac, the sandwich has two layers.) Between its two patties, the Grand Mac contains 1/3 pound of beef.The sandwiches are set to debut early next year. Come January, we'll be like Goldilocks, with three options at our fingertips. We won't know until then which size will be just right.