By comparison, a regular Big Mac contains 508 calories. While many McDonalds fans will be happy the Big Mac is back, with a whopping 731 calories it’s not for those who count calories, rising to 781 for those who add bacon. Likewise, how many calories does Big Mac Bacon have? The new Big Big Mac has 741 calories, according to McDonalds. Grand Mac Calories How many calories does a Big Mac have?