Baking powder vs. baking soda: How they’re different, which to use when and more Outlet: Washington Post 25 Jun, 2021 Washington Post: For every teaspoon of baking powder, suggests the Colorado State University Extension, reduce by ⅛ teaspoon at 3,500 to 6,500 feet; ⅛ to ¼ teaspoon at 6,500 to 8,500 feet; and ¼ teaspoon at 8,500 to 10,000 feet. link
