One of the easiest ways to visually estimate portion sizes is to use an everyday item that you carry around with you all the time, your hand.
 

1 ounce of cheese is about the size of your thumb

A teaspoon of margarine is about the size of your thumb tip


1 cup of milk, yogurt or chopped fresh greens is about the size of a small hand holding a tennis ball


1 oz nuts or small candies:
About one handful


2 oz chips or pretzels:
About two handfuls


1 cup: About the size of a man's fist


A cup of cut fruit, cooked vegetables, pasta, rice is about the size of a rounded handful
3 ounces of meat, poultry, or fish are about the size of a women's palm
1/2 cup of cut fruit, vegetables, or pasta is about the size of a small fist
One ounce of snack foods--pretzels, etc. equals a large handful