Mifflin Equation

Estimate resting metabolic rate (RMR) and daily caloric needs using the Mifflin–St Jeor equation (1990), one of the most validated RMR formulas in clinical nutrition research.

Formula (RMR)

• Men: RMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
• Women: RMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Total daily energy expenditure depends on activity level; this tool applies a multiplier to RMR when an activity factor is selected.

Background

Mifflin–St Jeor replaced older Harris–Benedict estimates for many populations and is recommended by the Academy of Nutrition and Dietetics for RMR prediction when indirect calorimetry is unavailable.

When to use it

Useful for rough meal-planning targets, weight-loss or gain planning, and educational comparisons between activity levels—not for prescribing medical diets.

Limitations

Individual metabolism varies with genetics, thyroid function, medications, lean mass, and adaptive thermogenesis during prolonged dieting. The equation underestimates needs for very muscular individuals and may be less accurate in certain ethnic groups or clinical states. Indirect calorimetry remains the gold standard.

Example

With weight 77 kg and height 177 cm, mifflin returns a numeric estimate.

This skill is available over A2A JSON-RPC and REST. When you already know the skill id and export, call execute directly—no discovery step required.

REST example

curl -sS -X POST https://toolplaza.app/api/helpers/execute \
  -H 'Content-Type: application/json' \
  -d '{"skillId":"caloric-needs__mifflin","export":"calculateMifflinStJeorCalories","args":[{"gender":"male","weight":70,"height":175,"age":30}]}'

A2A JSON-RPC example

Send POST https://toolplaza.app/api/a2a with:

{
  "jsonrpc": "2.0",
  "id": "1",
  "method": "message/send",
  "params": {
    "message": {
      "messageId": "uuid",
      "role": "user",
      "parts": [
        {
          "kind": "text",
          "text": "ignored"
        }
      ]
    },
    "metadata": {
      "toolplaza": {
        "skillId": "caloric-needs__mifflin",
        "export": "calculateMifflinStJeorCalories",
        "args": [
          {
            "gender": "male",
            "weight": 70,
            "height": 175,
            "age": 30
          }
        ]
      }
    }
  }
}

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