600KJ TO CALORIES?

http://www.convertunits.com/from/kilojoules/to/calorie+[nutritional]

That one is set to Nutritional Calories.
just type in Kj and it works.

BTW it is 143calories

The sites will probably work and be your best bet. But just because I'm a physical science nerd:

1 KJ = 1000 J
4.184 J = 1 calorie

So, 600,000 J * (1 calorie/4.184 J) = 143403 calories
However, when we see calories on the nutrition facts labels are actually kilocalories, or kcal. So, divide that by 1000, and you would get 143 kcal.