Recipe nutrition information - How to?

I mix several things together for a snack. How do I come up with the nutritional information when I'm not sure how much of what I toss in. Specifically, I make trail mix with mixed nuts, raisens and dried cranberries. The nuts included are peanuts, pistachio, sunflower nuts, almonds, cashews, and maybe brazil nuts. How do I come up with the calorie, fat, carb and other content for this? I usually have 1 cup at a time.