How do I work out calories burned from kilojoules?

I cant find this out, I have a Kettler cross trainer and when i was finished today it showed just over 600 kilojoules burned and in tiny letters beside it it has kilocalories (which i thought was calories/1000). However on the generic exercise list, I find elliptical trainer shows the same amount of time burns 325 calories. How do I work out the correct calorie value from kilojoules?? Thanks so much!