Here are some formulas that may help you calculate your exercise points:
Light Activity (you can feel it a bit but not too stressful):
Weight x Minutes x .000232 = Activity Points
Moderate Activity (you can feel your heart rate rise a bit and lightly perspite):
Weight x Minutes x .000327 = Activity Points
High Activity (heart rate rises and you break a good sweat):
Weight x Minutes x .0008077 = Activity Points
Hope this helps..