BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep vital organs functioning (breathing, heartbeat, temperature regulation). It represents about 60–75% of total daily calorie expenditure. BMR does not include physical activity, digestion, or daily movement.

Which BMR formula is most accurate?

The Mifflin-St Jeor equation (1990) is the most accurate for most adults. A landmark 2005 study in the Journal of the American Dietetic Association found it predicted resting metabolic rate within 10% for 82% of participants — better than the older Harris-Benedict formula. US dietitians and fitness apps typically use Mifflin-St Jeor. The UK's NHS and WHO use the Schofield equation for clinical nutrition, especially for children and hospitalized patients.

What BMR formula does the NHS use?

The UK's NHS uses the Henry (Schofield) equation for clinical nutrition assessments. This formula, originally published by Schofield in 1985, was adopted by WHO/FAO/UNU for international nutrition guidelines. The US uses Mifflin-St Jeor as the preferred formula in clinical dietetics since 2005. Both formulas give similar results for most adults (within 5–10%).

Does BMR change with age?

Yes. BMR decreases approximately 1–2% per decade after age 20, mainly due to loss of lean muscle mass (sarcopenia). At age 70, your BMR may be 15–20% lower than at age 20. This is why calorie needs decrease with age, and why resistance training to preserve muscle mass becomes increasingly important.

🇺🇸 Mifflin-St Jeor 🇬🇧 NHS Schofield 🌍 Harris-Benedict 💪 Katch-McArdle

BMR Calculator

Your Basal Metabolic Rate (BMR) is the calories your body burns at complete rest. Different countries and health authorities recommend different formulas — and the results can differ by 100–200 kcal/day.

Quick Answer

BMR is your resting calorie burn. Mifflin-St Jeor (1990) is the most accurate for most adults — recommended by US dietitians. The UK NHS uses the Schofield equation. Harris-Benedict is the classic formula still widely used internationally. To get TDEE (actual daily needs), multiply BMR by your activity multiplier (1.2–1.9×).

Sex

Age

Weight (kg)

Height (cm)

Body Fat % (optional — enables Katch-McArdle formula)

BMR Formula Comparison by Country

Formula	Used By	Year	Best For
🇺🇸 USA — Academy of Nutrition	Mifflin-St Jeor (1990)	1990	Standard for clinical dietetics since 2005 validation study
🇬🇧 UK — NHS / NICE	Schofield/Henry equation (1985)	1985	National clinical nutrition guidelines; diverse populations
🇨🇦 Canada — Dietitians of Canada	Mifflin-St Jeor (primary)	1990	Adopted alongside US/Australian guidelines
🇦🇺 Australia — Dietitians Australia	Mifflin-St Jeor (primary)	1990	Used in clinical and sports dietetics alongside WHO Schofield
🇯🇵 Japan — MHLW / JSPEN	Harris-Benedict (revised)	1919/1990	Widely cited in Japanese clinical nutrition literature
🌍 WHO / FAO / UNU globally	Schofield equation	1985	International nutrition planning, diverse populations & children

Mifflin-St Jeor Formula (Most Accurate)

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

Published in 1990 by Mifflin, St Jeor, Hill, and Scott, this formula was validated against indirect calorimetry in a 2005 study by Frankenfield et al. (Journal of the American Dietetic Association). It's now the preferred formula for clinical dietetics in the US, Canada, and Australia.

Frequently Asked Questions

What is the average BMR for a man? ▾

The average BMR for a 30-year-old, 70 kg, 175 cm male is approximately 1,695 kcal/day (Mifflin-St Jeor). BMR varies significantly with body size, composition, and age. Larger, more muscular individuals have higher BMRs.

What is the average BMR for a woman? ▾

The average BMR for a 30-year-old, 60 kg, 165 cm female is approximately 1,396 kcal/day (Mifflin-St Jeor). Women generally have lower BMRs than men of the same size due to lower average muscle mass and higher essential body fat percentage.

Why does the NHS use a different formula than the US? ▾

The UK NHS adopted the Schofield/Henry equation because it was derived from a large, diverse international dataset and adopted by WHO/FAO/UNU for global nutrition guidelines. US clinical dietetics adopted Mifflin-St Jeor in 2005 after a large validation study. For most healthy adults, the two formulas differ by fewer than 100 kcal/day.

How can I increase my BMR? ▾

BMR is primarily determined by lean body mass. Building and preserving muscle through resistance training is the most effective way to increase BMR long-term. Adequate protein intake (1.6–2.2 g/kg for active individuals) supports muscle mass. Some research suggests cold exposure and certain thyroid conditions affect BMR, but the effect is modest compared to muscle mass.

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Mifflin-St Jeor, Harris-Benedict, Schofield comparison

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Daily protein needs by goal and body weight

Sources & Methodology

Basal metabolic rate is estimated with the Mifflin–St Jeor equation (default), with Harris–Benedict and Katch–McArdle as alternatives where lean body mass is known.

Standards and figures reviewed 2026.