What is the difference between BMR and TDEE?

BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) includes BMR plus calories burned through physical activity, exercise, and digesting food. TDEE = BMR x activity multiplier (1.2 for sedentary to 1.9 for very active).

Should I eat below my BMR to lose weight?

Eating below your BMR for extended periods can slow your metabolism, cause muscle loss, and trigger nutritional deficiencies. Instead, eat between your BMR and TDEE to create a moderate caloric deficit of 500-750 calories for healthy weight loss.

Which BMR formula is most accurate?

The Mifflin-St Jeor equation (1990) is considered the most accurate for most people and is recommended by the Academy of Nutrition and Dietetics. The Harris-Benedict equation (1919, revised 1984) is also widely used but slightly less precise.

BMR Calculator

Find out how many calories your body burns at complete rest — your metabolic baseline.

BMR Calculator

Calculate your Basal Metabolic Rate

BMR Calculator

Mifflin-St Jeor equation

Weight (kg)

Height (cm)

Age (years)

Gender

Formula

BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161 (female) or +5 (male)

What Is Basal Metabolic Rate (BMR)?

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to sustain essential life functions while at complete rest — think breathing, blood circulation, maintaining body temperature, and repairing cells. It represents the absolute minimum energy your body requires just to stay alive, with no movement or digestion factored in. BMR is highly individual and varies based on your age, sex, height, and lean body mass.

BMR is often confused with TDEE (Total Daily Energy Expenditure), but they are different. BMR is your resting baseline; TDEE adds your activity level on top of it. Understanding your BMR is the first step in any weight management plan — whether your goal is to lose, gain, or maintain weight. Eating consistently below your BMR deprives your body of the energy it needs for vital functions and can slow your metabolism over time.

How to Use This Calculator

1Select your biological sex — the formula differs for men and women.
2Enter your age in years, height (cm or inches), and current weight (kg or lbs).
3Click Calculate to get your BMR result in calories per day.
4Use your BMR as a starting point: multiply by your activity factor to find your TDEE and set realistic calorie goals.

BMR Formulas

Mifflin-St Jeor (most accurate, recommended):
  Men:   BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
  Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Harris-Benedict (original, revised 1984):
  Men:   BMR = 88.362 + 13.397 × weight(kg) + 4.799 × height(cm) − 5.677 × age
  Women: BMR = 447.593 + 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age

The Mifflin-St Jeor equation is preferred for modern use because it has been validated against indirect calorimetry studies and tends to be more accurate across a wider range of body compositions. Remember: your BMR represents the absolute minimum calories your body needs — never eat below your BMR for an extended period without medical supervision.

Worked Examples

Example 1 — Woman, 28 years old, 60 kg, 165 cm

Using Mifflin-St Jeor: BMR = (10 × 60) + (6.25 × 165) − (5 × 28) − 161 = 600 + 1,031.25 − 140 − 161 = 1,330 cal/day. This woman needs at least 1,330 calories per day just to support her resting bodily functions.

Example 2 — Man, 35 years old, 85 kg, 180 cm

Using Mifflin-St Jeor: BMR = (10 × 85) + (6.25 × 180) − (5 × 35) + 5 = 850 + 1,125 − 175 + 5 = 1,805 cal/day. At rest, this man burns approximately 1,805 calories per day to maintain basic physiological processes.

Example 3 — Woman, 50 years old, 70 kg, 160 cm

Using Mifflin-St Jeor: BMR = (10 × 70) + (6.25 × 160) − (5 × 50) − 161 = 700 + 1,000 − 250 − 161 = 1,289 cal/day. As we age, BMR naturally declines — this example illustrates how age reduces the caloric baseline compared to younger individuals.

Frequently Asked Questions

What is the difference between BMR and RMR?▾

BMR (Basal Metabolic Rate) is measured under very strict conditions — complete physical and mental rest, fasted state, thermoneutral environment. RMR (Resting Metabolic Rate) is measured under more relaxed conditions and is typically 10–20% higher than BMR. In practice, most online calculators — including this one — calculate RMR but label it BMR, and the two terms are often used interchangeably.

Does BMR decrease with age?▾

Yes. BMR naturally declines with age, primarily because muscle mass tends to decrease as we get older (a process called sarcopenia) and hormonal changes reduce metabolic activity. After age 30, BMR typically drops by about 1–2% per decade. Staying active and preserving muscle mass through resistance training is the most effective way to slow this decline.

Can I increase my BMR?▾

Yes — the most impactful way is to build lean muscle mass through strength training. Muscle tissue is metabolically more active than fat tissue, meaning it burns more calories even at rest. Eating enough protein, staying hydrated, getting adequate sleep, and avoiding prolonged crash diets also help keep your BMR from dropping.

How does muscle mass affect BMR?▾

Muscle is significantly more metabolically active than body fat. Each pound of muscle burns roughly 6 calories per day at rest, compared to about 2 calories per day for fat. This is why two people of the same weight and height can have notably different BMRs depending on their body composition. Higher muscle mass = higher BMR = more calories burned daily without additional activity.

Is it safe to eat at my BMR?▾

Eating exactly at your BMR is generally not recommended for extended periods because your BMR represents the bare minimum your body needs to function — it does not account for any activity, including simply getting out of bed. For most people, eating at BMR level is too restrictive and can lead to muscle loss, fatigue, and metabolic adaptation. Always aim for a calorie intake that covers your TDEE minus a moderate deficit (typically 300–500 cal/day for gradual fat loss).