The Snack size Ziploc bags hold approximately 1 cup of whatever. After measuring 1 cup of cantaloupe, cherries, cereal, etc., I put it into a Snack size bag and I'm good to go. Easy to transport, and it stays fresh.
Bonus Feature: If a co-worker brings in fruit or a healthy snack to share, I'll use a Snack size bag to "measure" a cup or less of the treat...after I check the calories on SparkPeople, of course. ;o)