buttermilkThe best buttermilk substitute, with exact ratiosEvery buttermilk substitute with the exact ratio: soured milk, cream of tartar, plain yogurt, thinned Greek yogurt, sour cream, kefir and dried buttermilk powder, sourced to King Arthur Baking, Purdue Extension, America's Test Kitchen and USDA.Nora Ellison · Sep 16, 2026 · 7 min read