Chicken Breast question

Ok, so this is probably a dumb question...but I need some help.

We buy the bags of boneless, skinless chicken breasts from WalMart and I want to try to watch my serving sizes to help prevent overeating and such. Now in the bag there is about 6 huge chicken breasts (I am guessing they are whole).

The nutritional information says that there is 100 calories in a 4 oz serving and there is 10 servings in the bag. I don't have a kitchen scale yet and I don't know how to figure out how much is 4 ounces.

Is there any easy way to tell how much is 4 ounces without a scale?

Well just by basic math, if they are all the same size each one is about 6.75 oz each. So 4 oz would be like almost 2/3's of each of one. So 2 breasts would contain 3 servings or so. Probably closer to about 9 servings realistically.

I buy the Tyson boneless, skinless, chicken breast from Cost.. and one breast piece is about 120 - 130 grams which is 4 oz (roughly)... Once I finish trimming it, I'm left with about 110 - 120 grams. Visually, it is about the size of my palm (from base to fingertips) and about an inch thick at the thickest part..

Hope this helps!

Thanks for your replies! I went out and bought a kitchen scale but your suggestions helped with my dinner. :)