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How can I calculate the Amount Per Serving label in the nutrition facts.

Not basing it as a recipe where it is already stated but by ingredients. For example, I have a customized recipe, I want to know the amounts per serving based on my ingredients.

Divi
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John the programmer
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2 Answers2

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You set it arbitrarily, although hopefully based on some reasonable single portion size. Once you have the serving size, you calculate the nutritional information based upon it.

There is some rumor of stronger regulation forthcoming in the US to make portion size claims on labels more realistic, but that is not the case at this time.

SAJ14SAJ
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  • But to what do i base it from? Do i just add all the amounts per serving from all the ingredients and make that the new amounts per serving of the recipe? – John the programmer Mar 07 '14 at 10:57
  • You base it on judgment and knowledge... it isn't something you can automate. The unit even varies, portions of a whole (1/8 of a pie), cups (breakfast cereal), and so on. – SAJ14SAJ Mar 07 '14 at 10:59
  • Its too simple yet complex. How should i judge it? I certainly lack the knowledge on this things. Anyways, i was hoping there was some sort of simple calculation for the amounts per serving behind every recipe. Like its all a total of something from all the ingredients used. – John the programmer Mar 07 '14 at 11:01
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    No such calculation exists. You cannot solve this problem programmatically. Even if the recipe includes a yield, "36 cookies", you would have to decide if the serving size is one cookie or three. – SAJ14SAJ Mar 07 '14 at 11:04
  • What is serving per size actually? Is it how much you eat a plate? like a box of cookies contains 12 cookies then how much is the serving per size is it 12 since im eating it alone, or does it vary upon how i eat them? – John the programmer Mar 07 '14 at 11:06
  • @Johntheprogrammer http://en.wikipedia.org/wiki/MyPlate – BaffledCook Mar 07 '14 at 11:29
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    The question doesn't say anything about a specific country, so the paragraph about forthcoming regulation doesn't seem relevant. – Peter Taylor Mar 07 '14 at 12:37
  • @PeterTaylor It is relevant. If the US published standards for amount per serving, it'd give you something to go on, far better than just guessing or trying to deduce the rules that manufacturers tend to follow (which of course is country-dependent too). – Cascabel Mar 08 '14 at 02:14
  • @Jefromi, either you've also heard these rumours and hence have access to some unstated context, or you're making the (not entirely unreasonable, I grant) assumption that anyone who assumes that their local regulation is universal must be from the US. But even if you're correct, as the Hong-Kongese guidelines state, *note that the dietary habit (sic) of people in Hong Kong and overseas countries may not be the same*, and the US is almost certainly an outlier. – Peter Taylor Mar 08 '14 at 08:13
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    I'm not saying US regulations apply everywhere. But if you're trying to make an informed guess for serving size, given a choice between "I have no information, I will do it alone" and "I know some rules the US uses", the latter is definitely useful. – Cascabel Mar 08 '14 at 19:08
  • @Jefromi, that's true, and I'd have posted links to various guidelines if derobert's question hadn't raised doubts about what OP is really looking for. But one of us is being more subtle than intended, because I still don't think you've got my point that neither OP of the question nor OP of the answer mentioned any country. Rumours of stronger regulation forthcoming in an unspecified jurisdiction are completely useless to everyone. – Peter Taylor Mar 11 '14 at 08:39
  • @PeterTaylor I'm quite aware they didn't mention a country. That doesn't make my last comment less relevant. The question isn't about printing legal nutrition labels. The guy wants to make a web app that shows nutrition facts for custom recipes. – Cascabel Mar 11 '14 at 15:01
  • If I understand right, [this document](http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=101.12) might be the basis for the stronger regulation you mention. – Cascabel Dec 12 '15 at 20:17
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You have two problems here, one easy and one hard. The easy one is "how many servings are in this recipe?" As others have said, the recipe may make 36 cookies but is that 36 servings, or 12, or some other number? That is the easy problem in my opinion. Many recipes say "serves 8" or "serves 6" and you could work out the total numbers for if someone ate the entire batch, then calculate "I can't eat more than 2 of these" or "I should eat at least half of this to get enough protein" as needed.

The harder part is taking raw numbers like how much protein is in an egg or how many calories are in a cup of flour and working out how to combine them. Say you are frying chicken in 1/4 cup of oil. You certainly don't add the oil calories to the chicken calories - not all the oil ends up in the dish. But if you add oil to a cake batter, you will add the oil calories in to the calculation. Some forms of cooking affect some nutrients, so perhaps the Vitamin C in a long cooked fruit dish is not the same as the Vitamin C in the raw fruit you added to it. I don't know a general solution or technique for dealing with this. It depends what nutritional facts you care about (calories? fibre? fat? Vitamin C? B? E?) and how you are cooking the food. In addition if you are using "one apple" or "two carrots" you won't have the same precision as "100g of diced carrot" so your recipe may not be the same every time.

If you just want to know roughly the calories, just add up the calories of the raw ingredients and make some adjustments for ingredients that don't end up in your mouth. Beyond that I don't think it's possible.

Kate Gregory
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  • Interesting position. I think that the first part is already hard enough to make it unsolvable. The amount somebody can eat differs with the person. The amount a person predicts she can eat differs with her level of hunger at the moment she is making the prediction. Other external factors such as size of the plate, cookie size, mood during eating and parallel activity will also have a large influence. Basically, people 1) eat different portions of the same food under different circumstances, and 2) are lousy at predicting the average portion (which has too much variance anyway). – rumtscho Mar 11 '14 at 16:53