BMR Calculator

Gender

Age (years)

30 yrs

Weight (kg)

70 kg

Height (cm)

170 cm

Activity Level

Formula

Body Fat %

Goal (for macro targets)

📈 Results

BMR — Calories at Complete Rest

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TDEE by Activity Level:

Macronutrient Targets:

BMR Projection by Age:

Calorie Breakdown

TDEE by Activity

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Enter your details to calculate BMR & TDEE

Formula

BMR Formulas Explained

Mifflin-St Jeor (Recommended):

Men: BMR = 10×W + 6.25×H − 5×A + 5

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

Where:
W = weight (kg)
H = height (cm)
A = age (years)

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What is BMR?

Basal Metabolic Rate is the number of calories your body burns at complete rest to maintain basic life functions: breathing, circulation, cell production, and temperature regulation.

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What is TDEE?

Total Daily Energy Expenditure is your BMR multiplied by an activity factor. It represents the total calories you burn in a day including exercise, daily movement, and the thermic effect of food.

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Using TDEE for Goals

To lose weight: eat 300–500 calories below TDEE. To gain muscle: eat 200–300 calories above TDEE. To maintain: eat at TDEE. Extreme deficits can slow metabolism and cause muscle loss.

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Katch-McArdle Formula

Unlike Mifflin and Harris-Benedict, Katch-McArdle uses lean body mass (LBM) rather than total weight. It is the most accurate for very lean or very obese individuals where body composition differs significantly from average. Requires knowing your body fat %.

FAQ

Frequently Asked Questions

Common questions about BMR calculations

Which BMR formula is most accurate?

The Mifflin-St Jeor equation (1990) is the most accurate for most people — validated on a larger, more diverse population than Harris-Benedict. Harris-Benedict (revised 1984) tends to slightly overestimate BMR. Katch-McArdle is the most accurate for athletes and those with unusually high or low body fat, because it uses lean body mass rather than total weight. Use it if you know your body fat % from a DEXA scan or skinfold callipers.

Why does my BMR decrease with age?

BMR decreases by about 1-2% per decade after age 20. This happens because of muscle mass loss (sarcopenia), hormonal changes (lower testosterone and growth hormone), and reduced organ function. Resistance training helps preserve muscle mass and maintain a higher metabolic rate as you age.

Does eating more frequently boost BMR?

No — "meal frequency boosts metabolism" is a myth. Total daily caloric intake and macronutrient distribution matter far more than meal timing. The thermic effect of food is roughly 10% of total calories regardless of how many meals you eat. Protein has the highest thermic effect (20-30%) compared to carbs (5-10%) and fats (0-3%).

How can I increase my BMR?

The most effective ways to increase BMR: (1) Build muscle through strength training — muscle tissue burns more calories than fat at rest; (2) Adequate protein intake to preserve muscle; (3) Stay well hydrated; (4) Don't crash diet — severe caloric restriction lowers BMR; (5) Get sufficient sleep — sleep deprivation reduces metabolic rate.

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