The number of cups in a pound of alkalinity increaser (sodium bicarbonate or baking soda) can vary slightly depending on factors such as the density of the powder and how tightly packed it is. However, as a rough estimate: 1 pound of baking soda is approximately equal to 2.25 to 2.5 cups. To be more precise, you may want to measure it with a kitchen scale, especially if exact measurements are crucial for your application.