This is the formula you need: 1 Calorie [nutritional] = 4.186 8 kilojoules
I am from NZ and nutritional labels here are all in kilojoules too. I usually just round it up and divide the number in kilojoules by 4.19 to get the amount in calories. Hope that helps.
Funnily enough, even though are food are labelled in kilojoules I actually think in calories.
Aug 1st 2013: 156.2lbs (Start Weight)
Jul 1st 2014: 104lbs (and 42 inches lost)
Goal Weight: 101.8lbs (reached July 23rd 2014)