Alternatively you could enlarge the pattern shown which is at 1/6th. The pattern shown is a small size 4. The patterns are drawn to scale, 2 squares = 2.4 inches (6 cm).
Size Waist size R ¼ circle R ½ circle 1=2.4 in 1=1.6 in
4 24.5 in 16 in 8 in 6.7 5.0
6 26.5 in 17 in 8.5 in 7.1 5.3
8 28 in 18 in 9 in 7.5 5.7
10 29.5 in 19 in 9.5 in 8.0 6.0
12 31 in 20 in 10 in 8.4 6.3