Question: what is the standard size of a quilt block?
Answer: Now and days most quilt shops (both brick and mortar and online) sell a wide variety of precut squares in packs! Sizes may vary but the standard packs are either 10 inches by 10 inches, 5 inches by 5 inches, or 2.5 inches by 2.5 inches. So just decide what size blocks you would like to build with.