{
  "id": "net-carb",
  "version": "b32b40238db5",
  "status": "published",
  "name": "Net Carb Calculator",
  "question": "How many net carbs are in this?",
  "summary": "Works out net carbs from a Nutrition Facts label: total carbohydrate minus dietary fiber and all, half or none of the sugar alcohols, per serving and for the servings you eat.",
  "category": "food",
  "subcategory": "cooking",
  "url": "https://www.acalculator.org/food/net-carb-calculator",
  "markdown": "https://www.acalculator.org/food/net-carb-calculator.md",
  "kind": "function",
  "method": "Net carbs = total carbohydrate − dietary fiber − sugar alcohols × (1, ½ or 0). Net carbs eaten = net carbs per serving × servings.",
  "assumptions": [
    "“Net carbs” has no FDA definition; this is the common convention. Fiber and sugar alcohols are subtracted because they are not fully digested.",
    "Label values are per serving and already rounded on the label."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "c": {
        "title": "Total carbohydrate, g",
        "description": "Total carbohydrate per serving, from the label.",
        "type": "number",
        "minimum": 0,
        "maximum": 10000
      },
      "f": {
        "title": "Dietary fiber, g",
        "description": "Dietary fiber per serving, from the label.",
        "type": "number",
        "minimum": 0,
        "maximum": 10000
      },
      "sa": {
        "title": "Sugar alcohols, g",
        "description": "Sugar alcohols per serving, if the label lists them (0 if not).",
        "type": "number",
        "minimum": 0,
        "maximum": 10000
      },
      "r": {
        "title": "Subtract sugar alcohols",
        "description": "How much of the sugar alcohols to take off: all, half, or none.",
        "type": "string",
        "enum": [
          "all",
          "half",
          "none"
        ]
      },
      "n": {
        "title": "Servings eaten",
        "description": "How many servings you eat; 0.5 for half a serving.",
        "type": "number",
        "exclusiveMinimum": 0,
        "maximum": 1000
      }
    }
  },
  "outputs": {
    "net": {
      "label": "Net carbs per serving (g)",
      "description": "Total carbohydrate − fiber − the sugar alcohols you subtract.",
      "format": "number"
    },
    "netTotal": {
      "label": "Net carbs eaten (g)",
      "description": "Net carbs per serving × servings.",
      "format": "number"
    },
    "totalEaten": {
      "label": "Total carbohydrate eaten (g)",
      "description": "Total carbohydrate × servings.",
      "format": "number"
    },
    "subtracted": {
      "label": "Subtracted per serving (g)",
      "description": "Fiber plus the sugar alcohols you subtract.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "c": 46,
      "f": 7,
      "sa": 0,
      "r": "all",
      "n": 1
    },
    "outputs": {
      "net": 39,
      "netTotal": 39,
      "totalEaten": 46,
      "subtracted": 7
    },
    "text": "This has 39 g of net carbs per serving."
  },
  "examples": [
    {
      "given": {
        "c": 46,
        "f": 7,
        "sa": 0,
        "r": "all",
        "n": 4
      },
      "expect": {
        "net": 39,
        "netTotal": 156,
        "totalEaten": 184
      },
      "source": "FDA, Interactive Nutrition Facts Label: Total Carbohydrate (includes dietary fiber, total sugars and sugar alcohols; sample label 46 g total carbohydrate, 7 g fiber, 4 servings), https://www.accessdata.fda.gov/scripts/InteractiveNutritionFactsLabel/total-carbohydrate.cfm (retrieved 2026-10-03); hand calculation in content.mdx: 46 − 7 = 39 g; × 4 = 156 g"
    },
    {
      "given": {
        "c": 20,
        "f": 3,
        "sa": 10,
        "r": "half",
        "n": 1
      },
      "expect": {
        "net": 12,
        "subtracted": 8
      },
      "source": "FDA, Interactive Nutrition Facts Label: Total Carbohydrate (includes dietary fiber, total sugars and sugar alcohols; sample label 46 g total carbohydrate, 7 g fiber, 4 servings), https://www.accessdata.fda.gov/scripts/InteractiveNutritionFactsLabel/total-carbohydrate.cfm (retrieved 2026-10-03); hand calculation in content.mdx: 20 − 3 − 10 ÷ 2 = 12 g"
    },
    {
      "given": {
        "c": 20,
        "f": 3,
        "sa": 10,
        "r": "all",
        "n": 0.5
      },
      "expect": {
        "net": 7,
        "netTotal": 3.5
      },
      "source": "FDA, Interactive Nutrition Facts Label: Total Carbohydrate (includes dietary fiber, total sugars and sugar alcohols; sample label 46 g total carbohydrate, 7 g fiber, 4 servings), https://www.accessdata.fda.gov/scripts/InteractiveNutritionFactsLabel/total-carbohydrate.cfm (retrieved 2026-10-03); hand calculation in content.mdx: 20 − 3 − 10 = 7 g; half a serving 3.5 g"
    }
  ],
  "sources": [
    "FDA, Interactive Nutrition Facts Label: Total Carbohydrate. Total carbohydrate includes dietary fiber, total sugars and sugar alcohols; sample label with 46 g of total carbohydrate, 7 g of dietary fiber and 4 servings per container. Retrieved 2026-10-03. https://www.accessdata.fda.gov/scripts/InteractiveNutritionFactsLabel/total-carbohydrate.cfm",
    "FDA, How to Understand and Use the Nutrition Facts Label (serving sizes; dietary fiber DV 28 g). Retrieved 2026-10-03. https://www.fda.gov/food/nutrition-facts-label/how-understand-and-use-nutrition-facts-label"
  ],
  "related": [
    "food-calorie",
    "recipe-calorie",
    "recipe-scaler"
  ],
  "changelog": []
}