BMR Calculator

Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) — know exactly how many calories your body needs

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Frequently Asked Questions

BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain basic life functions — breathing, circulation, cell production, and temperature regulation. It accounts for 60–75% of total daily calorie expenditure for most people.

TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor. It represents the total calories you burn in a day including all physical activity. Eating at your TDEE maintains weight; eating below it causes weight loss, above it causes weight gain.

The Mifflin-St Jeor equation (1990) is considered the most accurate for most people. The Harris-Benedict equation (1919, revised 1984) tends to overestimate slightly. The Katch-McArdle formula is most accurate for lean individuals when lean body mass is known.

BMR increases with muscle mass (strength training), body weight, and youth. Key strategies: build muscle through resistance training, maintain adequate protein intake (prevents muscle loss), eat regular meals, stay hydrated, and get enough sleep. Muscle tissue burns more calories at rest than fat tissue.

A safe calorie deficit for weight loss is 500–750 calories below your TDEE, yielding approximately 0.5–0.7 kg per week. Never eat below your BMR for extended periods as this can slow metabolism, cause muscle loss, and nutrient deficiencies.

The Harris-Benedict formula (originally 1919, revised 1984) was the gold standard for decades but tends to overestimate BMR by about 5%. The Mifflin-St Jeor formula (1990) was validated against indirect calorimetry in a larger, more diverse population and is now preferred by most dietitians and the Academy of Nutrition and Dietetics. The practical difference in daily calorie estimates is typically 50–150 kcal, which can be meaningful over time when planning a diet.

BMR naturally declines with age, primarily due to a gradual loss of muscle mass (sarcopenia). After age 30, BMR drops by approximately 1–2% per decade. This means a 60-year-old may burn 150–300 fewer calories per day at rest compared to their 30-year-old self, even at the same weight. Resistance training and adequate protein intake are the most effective ways to slow this decline. Consult a healthcare professional before making significant dietary changes.

Start by calculating your TDEE (BMR × activity factor). To lose weight, create a calorie deficit of 500–750 kcal below your TDEE per day, which yields roughly 0.5–0.7 kg of fat loss per week. Avoid eating below your BMR, as this can cause muscle breakdown and metabolic adaptation. Track your weight over 2–3 weeks and adjust by 100–200 kcal if progress stalls. Always consult a healthcare professional before starting a calorie-restricted plan.

Cardiovascular exercise raises calorie burn only during the session itself and for a short time after (the "afterburn" or EPOC effect). However, resistance training can permanently raise BMR by building muscle mass — each kilogram of muscle burns approximately 13 kcal per day at rest compared to about 4.5 kcal for fat tissue. Over months and years, consistent strength training can meaningfully increase your resting metabolic rate. Aerobic fitness alone does not significantly raise resting BMR.

Yes — your body continues to burn calories during sleep to maintain vital functions including breathing, heart rate, cell repair, and temperature regulation. Calorie burn during sleep is roughly equivalent to your BMR, since physical activity is essentially zero. For an average adult, this is approximately 50–80 kcal per hour of sleep. Interestingly, the brain uses significant energy during REM sleep, so sleep quality can influence overnight calorie use.

About This BMR Calculator

This free BMR Calculator supports three formulas: Mifflin-St Jeor (recommended), Harris-Benedict (revised), and Katch-McArdle. It calculates your Basal Metabolic Rate and TDEE based on gender, age, height, weight, and activity level. A calorie goal table is shown for different objectives: weight loss, maintenance, and muscle gain.

BMR by Age (70 kg male, 175 cm)

Age	BMR (kcal)	TDEE (mod.)
20	1,875	2,906
25	1,850	2,868
30	1,800	2,790
40	1,750	2,713
50	1,700	2,635
60	1,650	2,558

Mifflin-St Jeor Formula

Male:
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5

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

Standards & References

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