I know the general rule of thumb is "the size of a deck of cards" before I heard this I was just measuring with a cup and punching the amount into my online food journal to keep track of my calories.
I usually do 1/2 - 2/3 cup cut up (not diced)
The calorie counter says thats about 140 calories [diced]. It fills me up fine, but it looks much more than the size of a deck of cards when I pour it out of the cup onto the plate.
-So is that too much of a serving size?

Just in case you need to know the chicken + the rest of my meal fills me up fine (veggies and such)


p.s don't say "if you feel good then its good" cause I'm a girl and I'm trying to keep my eye on the calories.