Per 100 g gives foods a common comparison basis. Per serving shows the nutrition in the amount you actually choose. Neither view is automatically “better”—they answer different questions.
Why nutrition values change when the amount changes
A nutrition value only makes sense when it is attached to an amount. If 100 g of a food contains 8 g of protein, a 50 g amount contains about 4 g and a 200 g amount contains about 16 g, assuming the same food and preparation. Calories, carbohydrates, fat, vitamins and minerals scale in the same way.
This is why Foodmanac keeps the source reference amount visible and lets you change the quantity. The calculation is simple, but the context matters: the food name, preparation, edible portion and data source must remain the same.
What “per 100 g” means
A 100-gram basis is a standardized way to display food composition. It is especially useful when two foods have different household serving descriptions. One food may be listed by cup, another by piece and another by tablespoon; placing both on a 100 g basis removes that serving-size difference.
- Use 100 g to compare the nutrient concentration of similar foods.
- Keep the preparation consistent: raw and cooked versions are different records.
- Check whether the source value refers to the edible portion.
- Do not assume 100 g is the amount you should eat.
For example, comparing 100 g of cooked rice with one cup of uncooked rice would mix both preparation and amount. A fair comparison would use cooked-versus-cooked values on the same gram basis.
What “per serving” means
A serving connects nutrition data to a practical quantity such as one cup, one slice or one piece. On U.S. packaged-food labels, the FDA explains that serving sizes reflect amounts people typically consume; they are not recommendations for how much a person should eat. The familiar household measure is normally followed by its metric weight in grams.
Serving information is useful when your question is practical: “What does this bowl, slice or measured amount provide?” If you eat twice the listed serving, the calories and nutrient amounts are approximately doubled. If you eat half, they are approximately halved.
Per 100 g versus per serving: which should you use?
| Your question | Best starting view |
|---|---|
| Which of two similar foods is more nutrient-dense? | Use the same 100 g basis. |
| What does the amount on my plate provide? | Use a serving or enter the actual grams. |
| How do two package labels compare? | First make the serving sizes equal. |
| How does cooking affect the result? | Compare matching raw or cooked records separately. |
| How much is in a recipe? | Use each ingredient’s actual amount in Mix Lab. |
A simple calculation
To convert a value from 100 g to another gram amount:
Adjusted nutrient amount = value per 100 g × selected grams ÷ 100
If a food provides 2.4 g of dietary fiber per 100 g, a 150 g amount provides approximately 3.6 g. Foodmanac performs this calculation automatically when you change the amount on a food page.
Use Foodmanac for both views
Open Explore Foods, choose a specific food and preparation, and change the amount from the documented reference value. For a side-by-side view, open Compare Foods and use one consistent basis. For a recipe or meal, add the real ingredient quantities in Mix Lab.