I bought some lentils recently, then I ate them. According to the package, the 128 grams (dry) I made for myself had 280 calories. However, the meal felt pretty heavy, so I looked up the nutritional information for dry lentils online and found this: http://nutritiondata.self.com/facts/legumes-and-legume-products/4337/2
So according to this site (which says the information was supplied by "USDA SR-21"), those 128 grams of lentils should have ~452 calories. That's a pretty big difference from 280. Now both brands of lentils I bought (Jack Rabbit and Stop & Shop) give the same numbers, 32g gives 70 calories.
So what do you trust, what's on the package or what the USDA says?
I was also doing the math on the link above. According to Nutrition Data 100g of dry lentils have 60g of carbohydrates, 30g of fiber, 26g of protein, and 1g of fat. Now, I was under the impression that fiber, being listed within the carbohydrate section, is added to the total carbohydrate value listed. Also, fiber presumably has no calories. That means we have 30g of carbs, 26g of protein, and 1g of fat, giving 30*4 + 26*4 + 1*9 = 233 calories in 100g of dry lentils. Then 233*0.32 = 74.56, very close to the information on my packaged lentils. But if I don't subtract the fiber from the carbohydrates then we have 60*4 + 26*4 + 1*9 = 353 calories, which is exactly what the USDA lists for 100g of lentils.