Unfortunately I'm not familiar with the english and US measurements so I would be very grateful if someone could help me out with this issue.
American cup measurements go by volume not weight so it's difficult to convert.
A typical 'serving' of fruit or vegetables is about 100-150g. Because the calorie-count tends to be quite low, you don't have to be too precise.
Thank you for your answers
For all kinds of conversions try: http://www.onlineconversion.com/
I find this very useful. I've used to understand historical measurements like cubits etc.
The UK cup size is larger then the US (1 UK Cup =1.20095 US Cup), although generally in the UK we don't use cup measurements for cooking. However as this is an US based site, I think it is useful to know for logging purposes at least.
Naturally volume and weight are not the same thing. A cup full of cornflakes will not be the same as a cup full of nuts. If you need to find out weight, then get some kitchen scales.
Calorie Count has it's own unit converter.