NO, it's NOT thousands of calories.

For anyone reading this and thinking, holy crap, I have to reduce my juice intake: DON'T.

There are between 80 and 140 calories in 8 oz of juice, with most fruit juices having around 110 / 8oz (regardless of whether they are fresh or store-bought).

So, to do the simple math:

45 oz / 8 oz = 5.6 servings
5.6 * 110 cal = 620 calories

Please, before saying or doing something ridiculous like the poster above, do some math.