You will need one button. Rowan used a 1 1/8” (2.8 cm) button.

Finished measurements:
Bust circumference: 38(42.25, 45, 49.5, 43.75)“ 96.5(107.5, 114.5, 125.5, 136.5) cm
Finished length: 27.5(28.25, 29.25, 30, 30.75)” 70(72, 74, 76, 78) cm
Sleeve length: 17.75(17.75, 18, 18, 18)“ 45(45, 46, 46, 46) cm

Yarn used:
Rowan Denim Revive
Shade 210 Cream - 16(18, 20, 21, 23) balls