Generally speaking, delivery orders that are less than $20 are given a minimum tip of $3. If the order is over $20, then it's customary to calculate a tip that is 10%-15% of the order (but never less than $5).
In one Reddit discussion, for example, opinions range from 10% to 20% of the bill, with some folks saying it depends on how far away the catering company is. The Emily Post Institute recommends that all food delivery people be tipped 10% to 15% of the bill regardless of other factors.
A new survey shows that on average, only 15.7 percent of Americans tip their driver when getting food delivered, and 64 percent of them tip a percentage of the food cost versus a flat amount.
Some orders may include an additional “delivery fee”, but this is not a tip – drivers do not receive this money – so make sure not to deduct this charge from your tip amount.
Just as in Japan, it is not customary to tip in China. Tipping in China is generally uncommon and can even be considered rude or embarrassing in some circumstances so when taking a taxi, enjoying a refreshing drink or tucking into a delicious meal there's no requirement to leave any gratuities.