Size is on the smaller size. If you are using a pattern for your baby quilt, follow those instructions. 20 FREE baby quilts that are easy, simple and even for beginners – from start to finish these handmade baby quilts you can sew at home. Some are simple designs that you can sew in a day. A quilt can vary 4″ – 8″ depending on the pattern you choose. Most baby mattresses are 52 inches by 27 inches, so your quilt should fit comfortably into the crib. If you are ready to start quilting…a smaller easy quilts… baby quilts are the perfect place to start. The baby quilt size is best left to your interpretation… using your own judgment and approximations. Most standard crib quilts are rectangular, measuring about 52 inches by 34 inches.