Scale Food Nutrition From Per 100g to Grams Serving API

Every major food nutrition API stores macros per 100g. Users log 150 g or 2.5 oz. Your app must scale food nutrition per 100g to grams serving accurately. Calorie API offers both client-side math and a portion calc endpoint.

The Formula

scaled_value = (grams / 100) * per_100g_value

Example: 200g chicken, 31g protein per 100g:

protein = (200 / 100) * 31 = 62g

Apply to calories, carbs, fat, fiber, and sodium.

Option A: Client-Side Scale

After GET /foods/{id}:

function scaleNutrients(food, grams) {
  const ratio = grams / 100;
  return {
    calories: food.calories * ratio,
    proteinG: food.protein_g * ratio,
    carbsG: food.carbohydrates_g * ratio,
    fatG: food.fat_g * ratio,
  };
}

Best when you already fetched detail and want instant UI updates as user drags a slider.

Option B: Portion Calc API

curl "https://api.calorieapi.com/api/v1/public/calc/portion?food_id=12345&grams=200"

Returns scaled macros server-side. Best when you want one source of truth and fewer client bugs.

Ounces Input

Convert before scaling:

const grams = ounces * 28.3495;

Keep grams as canonical storage in your database.

Edge Cases

Used By Every Vertical

• Diabetes carb counting
• Bodybuilding macros
• Meal prep containers

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