健康・フィットネス

基礎代謝計算機

完全安静時の消費カロリー（基礎代謝率）を計算

使い方
  1. Select your Gender and enter your 年齢.
  2. Enter your 身長 in cm and 体重 in kg.
  3. Click Calculate BMR to find out how many calories your body needs to maintain basic life functions at rest.

計算式

This calculator uses the Mifflin-St Jeor Equation, widely considered the most accurate standard for BMR calculation:

  • Men: BMR = (10 × weight) + (6.25 × height) - (5 × age) + 5
  • Women: BMR = (10 × weight) + (6.25 × height) - (5 × age) - 161

Note: This is your basal metabolic rate, not your total daily energy expenditure (which factors in physical activity).

What Is Basal Metabolic Rate (BMR)?

Basal Metabolic Rate (BMR) is the number of calories your body needs to sustain its most fundamental physiological processes—breathing, circulation, cell repair, thermoregulation, and organ function—while at complete rest. It represents the single largest component of total energy expenditure for most sedentary individuals, typically accounting for 60–75% of daily calorie burn.

Understanding your BMR is the essential first step in any evidence-based nutrition or weight-management strategy. It sets your absolute minimum caloric floor—eating significantly below your BMR for extended periods triggers adaptive thermogenesis, where your body downregulates metabolism to conserve energy, making fat loss progressively harder. The Wikipedia article on Basal Metabolic Rate provides a detailed scientific overview of BMR and its measurement history.

Mifflin-St Jeor vs. Other BMR Formulas

Several equations have been developed to estimate BMR from easily measurable variables. Our calculator uses the gold-standard Mifflin-St Jeor Equation (1990), validated across large diverse populations and recommended by the Academy of Nutrition and Dietetics as the most accurate for general use.

✅ Most Accurate
Mifflin-St Jeor (1990)

Men: BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161

Validated in multiple large trials; ±10% accuracy for most adults
Classic
Harris-Benedict (1919, revised 1984)

Older formula; tends to overestimate BMR by 5% in some populations

Still widely used in clinical settings
Body-Fat Based
Katch-McArdle

Uses lean body mass instead of total weight; most accurate for lean athletes with known body fat %

Requires body fat measurement (see our 体脂肪率計算機)

What Factors Influence Your BMR?

BMR is not a fixed number—it shifts with biological and lifestyle changes. Key determinants include:

🏋️
Muscle Mass — Skeletal muscle is metabolically expensive, burning ~6 kcal/kg/day at rest versus ~2 kcal/kg/day for fat tissue. Building muscle is the most effective long-term strategy for raising BMR.
📅
年齢 — BMR typically declines by 1–2% per decade after age 30, primarily due to sarcopenia (age-related muscle loss). Resistance training largely counters this decline.
⚧
Biological Sex — Men generally have higher BMRs than women of the same height and weight due to greater lean mass and lower body fat percentage.
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Thyroid Function — The thyroid gland regulates metabolic rate. Hypothyroidism (underactive thyroid) can suppress BMR by 10–30%, while hyperthyroidism can elevate it significantly.
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Genetics — Individual variation in metabolic efficiency accounts for up to 40% of inter-person BMR differences, independent of body composition. Research from the NIH on genetic determinants of BMR supports this.

How to Use Your BMR for Weight Management

BMR alone is not your daily calorie target—it's your metabolic baseline. To get your Total Daily Energy Expenditure (TDEE), multiply your BMR by an activity factor:

📊
TDEE = BMR × Activity Multiplier
Sedentary (×1.2) → Light Active (×1.375) → Moderate (×1.55) → Very Active (×1.725) → Athlete (×1.9)
Use our 1日の総消費カロリー計算機 for the full breakdown.

Once you know your TDEE, subtract 500 kcal/day for a sustainable ~0.5 kg/week weight loss, or add 250–500 kcal for gradual muscle-building. Pair BMR data with our カロリー計算機 and BMI計算機 for a complete metabolic picture.

Frequently Asked Questions About BMR

What is a normal BMR for a woman?

For adult women, average BMR typically ranges from 1,200–1,500 kcal/day, though this varies substantially with body size, age, and muscle mass. A shorter, older, lighter woman may have a BMR below 1,200, while a tall, muscular young woman may exceed 1,600.

Can I increase my BMR naturally?

Yes. The most evidence-backed approach is progressive resistance training to build skeletal muscle. Studies show each pound of gained muscle increases resting calorie burn by approximately 6–7 kcal/day. High-protein diets (via the thermic effect of food) and avoiding extreme caloric restriction (which triggers adaptive thermogenesis) also help preserve and raise BMR.

How accurate is this BMR calculator?

The Mifflin-St Jeor formula predicts BMR within ±10% for approximately 82% of individuals when compared to gold-standard indirect calorimetry measurements. No formula based solely on height, weight, age, and sex can perfectly predict the metabolic output of every unique individual.

Does BMR change during a diet?

Yes—this is known as metabolic adaptation or adaptive thermogenesis. During sustained caloric restriction, the body reduces BMR by 10–20% as a survival mechanism. This is why weight-loss plateaus are so common and why diet breaks, refeeds, and resistance training are important strategies in long-term fat-loss programming.

Related Health & Nutrition Calculators

📊
1日の総消費カロリー計算機Find total daily calorie burn by activity level
 🔥
カロリー計算機Personalised daily calorie target for your goal
 ⚖️
BMI計算機Body Mass Index with healthy weight range
 📉
体脂肪率計算機Estimate body fat % using the Navy method
 🎯
理想体重計算機Four medical formulas for ideal body weight

References & Further Reading

  1. Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
  2. Wikipedia contributors. Basal Metabolic Rate. Wikipedia, The Free Encyclopedia.
  3. Frankenfield D, et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. J Am Diet Assoc, 2005.
  4. NIH. Factors Affecting Weight & Health. NIDDK, 2023.