On average, less healthful items were underestimated by more than 600 calories. But even among those who should have more knowledge about food values, errors of judgment are not uncommon. Nutritionists, for example, underestimated calorie values by 200 to 600 calories. So how will you do? Test yourself and see if you can figure out how much just one of each item below will cost you in term of calories.

Nabisco Ritz Snack Cracker vs. Nabisco Nilla Wafer vs. Nabisco Triscuit Reduced Fat

Most people are shocked to find out how many calories are in a single cookie or cracker. All these are relatively high. One Ritz Cracker has 16 calories; one Nilla Wafer has 17.5 calories; and the Triscuit Reduced Fat has 17 calories. Just think about how many of these you eat sitting in front of the TV or at your desk — the calories can add up very quickly.

One Almond vs. One Dried Plum (Prune)

They’re both pretty powerful, nutrient-dense foods. Dried plums are packed with important vitamins and minerals, including potassium, vitamin A, magnesium and iron, all of which help you stay healthy, balanced and energized. Dried plums are also high in disease-fighting anti-aging antioxidants and fiber. However, there are 22 calories in each one. Almonds are seven calories each. No, that’s not a misprint — they are each seven calories. So you need to be cautious about eating several handfuls. A small handful (about 1 ounce or 23 nuts and 161 calories) provides an excellent source of vitamin E and magnesium, a good source of protein, riboflavin and fiber, and also offers significant quantities of potassium, calcium, phosphorous, iron and monounsaturated fat.

One Sip of Campbell’s Chunky New England Clam Chowder vs. Campbell’s Healthy Request Mexican-Style Chicken Tortilla Soup

Each sip of the New England Clam Chowder is slightly less than 4.4 calories, compared with a sip of Mexican-Style Chicken Tortilla Soup, which is just 2.3 calories. Soup is great if you’re looking for something to fill you up. Because soups are water-based, they tend make you feel less hungry without adding too many calories, so you eat less as a result ­ which is certainly very helpful in terms of losing weight. Barbara Rolls, Ph.D., a professor of nutrition at Penn State University, has led several studies that show eating soup can help you lose weight. One study actually found that eating soup at the beginning of your meal could reduce your total mealtime consumption by as much as 100 calories.

One Bite of Prime Rib vs. One Bite of Filet Mignon

Prime rib is typically very fatty and, as a result, high in calories. So what does a bite cost caloriewise? Thirty-one calories, or nearly eight minutes of walking to burn it off. What about the filet mignon? That’s 19 calories a bite and clearly the better deal. There is much less fat in the filet. So make sure to think twice before you choose the prime rib over the filet. Another thing to keep in mind is that the filet is typically served in a 6- to 8-ounce portion, whereas a serving of prime rib is typically between 16 and 20 ounces. That can add up to more than 1,000 calories (more than half what you should get in an entire day).

If you are going to order a steak — try sharing. Or, as soon as you get your steak, try cutting it in half and taking a portion home. Better yet, ask the server to do it in the kitchen ­ that way you won’t have to struggle with the knife or your willpower. Also, make sure to trim off any visible fat, which can save as much as 25 percent of the calories. This is especially key for the fatty cuts like prime rib, porterhouse and T-bone, but you won’t save much fat from a sirloin or filet.

One Starburst Fruit Chew, Original vs. One Tootsie Roll Midgee

Just one Starburst is 20 calories, and one Tootsie Roll Midgee is 23 calories. As far as foods are concerned, these are obviously candies — and not the healthiest choices — but who would have thought that just one could be so high in calories? The good news is that you don’t just pop them in your mouth, chew and swallow. These candies take a bit of work to eat, which makes them a slightly better bet than other candies because they last longer and you may be able to get away with eating just one. It would take about five minutes to walk off the Starburst, and about six to walk off the Tootsie Roll Midgee.

One Potato Chip vs. One Tortilla Chip vs. One Peanut

One potato chip is about 10 calories — pretty high considering how many chips we generally consume in one sitting. They’re pretty addictive. If you love chips, try Popchips, which have only five calories each. Tortilla chips are about 16 to 20 calories per chip. And normally with tortilla chips people use some sort of dip, which adds even more calories. Use light or baked tortilla chips to reduce the per-chip calories, and switch from more calorically dense dips to salsa — 2 tablespoons have only about 15 calories.

Now for the peanut. You’re looking at 5.5 calories for each one — not bad (unless you’re taking handfuls at a time). And peanuts are also packed with nutrients, including vitamin E, folate, fiber, niacin and magnesium. One of the best things about peanuts is that they contain a large amount of protein, and protein helps keep you feeling full longer.