How much juice should a three year old drink?

It depends on the nature of the juice in question. If the juice contains a relatively large amount of sugar, it is preferable to limit the amount consumed by young children, as it can have a negative impact on health, and is best avoided. If the juice has a low sugar content, and high fruit content, it is much more nutritious, and may be consumed in greater quantities.

In the case of a three-year-old, about 750mL of juice per day is more than enough.