{
  "id": "weight-loss-percentage",
  "version": "76fb344849bd",
  "status": "published",
  "name": "Weight Loss Percentage Calculator",
  "question": "What is my weight loss percentage?",
  "summary": "Works out the percent of body weight lost from a starting and a current weight, the weight lost, or the weight to reach a percent goal such as the 5% to 10% that NIH suggests.",
  "category": "health",
  "subcategory": "body",
  "url": "https://www.acalculator.org/health/weight-loss-percentage-calculator",
  "markdown": "https://www.acalculator.org/health/weight-loss-percentage-calculator.md",
  "kind": "formulas",
  "method": "Weight loss percentage = (starting weight − current weight) ÷ starting weight × 100.",
  "assumptions": [
    "Both weights are measured the same way (same scale, same time of day, similar clothing).",
    "A current weight above the starting weight gives a negative percent: a gain."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "start": {
        "title": "Starting weight",
        "description": "Your weight before you started losing weight.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "exclusiveMinimum": 0,
        "maximum": 700
      },
      "now": {
        "title": "Current weight",
        "description": "Your weight now, or the weight you aim for.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "exclusiveMinimum": 0,
        "maximum": 700
      },
      "pct": {
        "title": "Weight loss percentage",
        "description": "The share of the starting weight lost; negative if weight was gained.",
        "type": "number",
        "x-unit": "percent",
        "minimum": -500,
        "exclusiveMaximum": 100
      }
    }
  },
  "solve": {
    "fillAny": 2,
    "variables": [
      "start",
      "now",
      "pct"
    ],
    "inputsOnly": []
  },
  "outputs": {
    "start": {
      "label": "Starting weight",
      "description": "Your weight before you started losing weight.",
      "format": "quantity"
    },
    "current": {
      "label": "Current weight",
      "description": "Your weight now, or the weight you aim for.",
      "format": "quantity"
    },
    "percent": {
      "label": "Weight loss percentage",
      "description": "The share of the starting weight lost; negative if weight was gained.",
      "format": "percent"
    },
    "lost": {
      "label": "Weight lost",
      "description": "The starting weight minus the current weight; negative if weight was gained.",
      "format": "quantity",
      "unit": "lb"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "start": 90.718474,
      "now": 83.91458845000001
    },
    "outputs": {
      "percent": 7.4999999999999885,
      "lost": 6.80388554999999
    },
    "text": "Going from 200 lb to 185 lb is a weight loss of 7.5% (15 lb)."
  },
  "examples": [
    {
      "given": {
        "start": 90.718474,
        "pct": 10
      },
      "expect": {
        "now": 81.6466266,
        "lost": 9.071847399999996
      },
      "source": "NIDDK (NIH), Your Game Plan to Prevent Type 2 Diabetes: lose 5 to 10 percent of your weight; at 200 pounds a 10 percent goal is 20 pounds, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan; hand calculation in content.mdx: 200 × 0.9 = 180 lb, 20 lb lost"
    },
    {
      "given": {
        "start": 90.718474,
        "pct": 5
      },
      "expect": {
        "now": 86.1825503,
        "lost": 4.535923699999998
      },
      "source": "CDC, Steps for Losing Weight: a 5% weight reduction for a person who weighs 200 pounds is 10 pounds, https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html; hand calculation in content.mdx: 200 × 0.95 = 190 lb"
    },
    {
      "given": {
        "start": 81.6466266,
        "now": 77.56429527
      },
      "expect": {
        "pct": 5.000000000000003,
        "lost": 4.082331330000002
      },
      "source": "hand calculation in content.mdx: (180 − 171) ÷ 180 × 100 = 5%; NIDDK (NIH), Your Game Plan to Prevent Type 2 Diabetes: lose 5 to 10 percent of your weight; at 200 pounds a 10 percent goal is 20 pounds, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan"
    },
    {
      "given": {
        "start": 95,
        "now": 85.5
      },
      "expect": {
        "pct": 10,
        "lost": 9.5
      },
      "source": "hand calculation in content.mdx: (95 − 85.5) ÷ 95 × 100 = 10%; NIDDK (NIH), Your Game Plan to Prevent Type 2 Diabetes: lose 5 to 10 percent of your weight; at 200 pounds a 10 percent goal is 20 pounds, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan"
    },
    {
      "given": {
        "start": 68.0388555,
        "now": 70.76040972
      },
      "expect": {
        "pct": -4.000000000000002,
        "lost": -2.7215542200000016
      },
      "source": "hand calculation in content.mdx: (150 − 156) ÷ 150 × 100 = −4%; CDC, Steps for Losing Weight: a 5% weight reduction for a person who weighs 200 pounds is 10 pounds, https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html"
    }
  ],
  "sources": [
    "NIDDK (National Institutes of Health), Your Game Plan to Prevent Type 2 Diabetes: try to lose at least 5 to 10 percent of your current weight; at 200 pounds a 10 percent goal is 20 pounds. Retrieved 2026-10-02. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan",
    "NIDDK, Health Tips for Adults: an initial goal of 5 to 10 percent of your starting weight; at 200 pounds, 10 to 20 pounds. Retrieved 2026-10-02. https://www.niddk.nih.gov/health-information/weight-management/healthy-eating-physical-activity-for-life/health-tips-for-adults",
    "CDC, Steps for Losing Weight: modest weight loss can improve blood pressure, cholesterol and blood sugar; a 5% reduction for a person who weighs 200 pounds is 10 pounds. Retrieved 2026-10-02. https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html"
  ],
  "related": [
    "weight-loss",
    "bmi",
    "ideal-weight",
    "calorie"
  ],
  "changelog": []
}