It will depend on the pattern you are going to use, how many different shades of blue, the background fabric if any and also how you plan to piece the backing fabric or planning to use wide backing on it and what fabric you plan for the binding.
Since you only make, have made, twin size, what general amounts have you needed to use before is a good partial ballpark guide as well more importantly, what I wrote above.
Last edited by quiltsfor; 02-26-2023 at 03:15 AM.