At a density of 125.0 g/US cup: 1 lb = 3.63 cups and 1 cup = 0.2756 lb for Flour (all-purpose).
Cups measure volume; pounds measure weight. Dense ingredients like honey or salt weigh much more per cup than light ones like cake flour or cocoa powder.
Next stepFor best accuracy in baking, weigh your ingredients on a kitchen scale rather than relying on cup measures, which can vary by 20-30% depending on how the cup is filled.