How is ‘% Daily Value’ on a food label calculated?

The amount of a nutrient in one serving of a product is divided by the daily recommended amount to give you the % Daily Value.

This product has 25 grams of total carbohydrates in one serving. The recommended amount of total carbohydrates is 300 grams on a 2,000 calorie diet.

Here’s the math:
25 grams of total carbohydrates
300 grams of recommended carbohydrates

= 0.08 (or 8%) of the daily recommended amount of carbohydrates