7-8 cups. After the dumpling season is over you can exchange 1 voucher for 7-8 medium cup coffee vouchers. Bucks medium cup e-vouchers are sold online, a 25 yuan; a Starbucks dumplings coupon after 20% discount is 158 yuan, converted into a medium cup e-voucher is almost 6 cups, so if you can exchange 7-8 beverage coupons that regardless of whether the dumplings can be sold, certainly not a loss.