You may have heard, but measuring cup size can vary from brand to brand. This problem is further amplified when it comes to measuring dry ingredients. Depending on elements like humidity and compaction, more or less flour may end up in your measuring cup.
More and more recipes (especially for baked goods) are also giving weight measurements nowadays, and I love using my scale to make sure my baked goods come out perfectly, or that I’m using the correct amount of tomatoes/potatoes/ etc. Scales can be found inexpensively at home goods stores, but if you’d rather not make the investment that’s perfectly fine. Just note that if something doesn’t turn out quite right it could be your measurements are off, and maybe try adjusting your quantities to see if it helps.