What size mixing bowls do I need?

At minimum, you need three sizes: a small (1 2 qt) for whisking eggs, dressings, and small tasks; a medium (3 4 qt) for mixing batters and tossing salads; and a large (5 8 qt) for bread dough, large batches, and marinating. If buying a single bowl, a 5 quart is the most versatile all purpose size.