BMR (Basal Metabolic Rate) Calculator

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BMR (Basal Metabolic Rate) Calculator

Find out how many calories your body burns at rest using our BMR calculator.

years
cm
kg
%
Men: 10-20% (athletic: 6-13%) | Women: 16-24% (athletic: 14-20%)
Quick Tips
  • Never eat below your BMR for extended periods — it can cause muscle loss and metabolic slowdown.
  • Mifflin-St Jeor is the most accurate formula for most modern adults.
  • Katch-McArdle is more precise if you know your body fat percentage, especially for athletes.
  • Recalculate every 10-15 lbs of weight change since BMR shifts as your body does.

Your BMR

1,674
calories/day at rest
Total Daily Energy (TDEE)
2,594
Maintenance Calories
2,594

Last updated: August 10, 2026

BMR: Your Body's Baseline Calorie Burn

BMR = calories burned doing absolutely nothing. If you stayed in bed all day, your body still burns energy for breathing, heartbeat, cell repair, brain function. For a 30-year-old woman, 5'5", 150 lbs: BMR = 1,450 calories. That's 60-75% of total daily burn. The rest comes from movement and digestion.

BMR differs from TDEE (Total Daily Energy Expenditure). BMR × activity multiplier = TDEE. Someone with 1,450 BMR who exercises moderately needs 2,258 total calories daily (1,450 × 1.55). Eat at BMR = lose weight. Eat at TDEE = maintain. Most people confuse these and wonder why diets fail.

BMR Calculation Methods

Mifflin-St Jeor (Most Accurate)

Men:

10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5

Women:

10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161

Harris-Benedict (Original)

Men:

13.4 × weight(kg) + 4.8 × height(cm) - 5.7 × age + 88.4

Women:

9.2 × weight(kg) + 3.1 × height(cm) - 4.3 × age + 447.6

Note: Mifflin-St Jeor is more accurate for modern populations. Harris-Benedict often overestimates by 5-10%.

BMR to TDEE: Activity Multipliers

Activity Level Description Multiplier
Sedentary Desk job, no exercise BMR × 1.2
Lightly Active Light exercise 1-3 days/week BMR × 1.375
Moderately Active Moderate exercise 3-5 days/week BMR × 1.55
Very Active Hard exercise 6-7 days/week BMR × 1.725
Extra Active Athlete, physical job + training BMR × 1.9
Reality Check: Most people overestimate activity level. Going to gym 3x/week but sitting 8 hours = "lightly active," not "moderately active."

Factors That Affect BMR

Increases BMR

  • Muscle mass: +6 cal/lb muscle vs. +2 cal/lb fat
  • Height: Taller = higher BMR
  • Youth: Metabolism peaks at 20s
  • Male sex: Men have 5-10% higher BMR
  • Pregnancy/lactation: +300-500 cal/day
  • Fever/illness: 7% per 1°F increase

Decreases BMR

  • Aging: -1-2% per decade after 30
  • Crash dieting: Adaptive thermogenesis
  • Fat loss: Less mass to maintain
  • Muscle loss: From inactivity/aging
  • Hypothyroidism: 10-30% reduction
  • Sleep deprivation: 2-5% decrease

BMR Examples by Demographics

30-Year-Old Woman

5'5" (165 cm), 150 lbs (68 kg)

BMR: 1,450 calories/day

TDEE if moderately active: 2,248 cal

30-Year-Old Man

5'10" (178 cm), 180 lbs (82 kg)

BMR: 1,850 calories/day

TDEE if moderately active: 2,868 cal

50-Year-Old Woman

5'5" (165 cm), 150 lbs (68 kg)

BMR: 1,350 calories/day

100 cal/day less than age 30

50-Year-Old Man

5'10" (178 cm), 180 lbs (82 kg)

BMR: 1,750 calories/day

100 cal/day less than age 30

How to Use Your BMR

For Weight Loss

  • Never eat below BMR for extended periods (causes muscle loss)
  • Calculate TDEE (BMR × activity level)
  • Subtract 500 cal from TDEE for 1 lb/week loss
  • Example: 1,450 BMR → 2,248 TDEE → eat 1,750 cal/day

For Muscle Gain

  • Eat 250-500 cal above TDEE
  • Higher protein: 0.7-1g per lb body weight
  • Strength train 3-5x/week to direct surplus to muscle

For Maintenance

  • Eat at your TDEE level
  • Adjust every 2-3 months as weight/activity changes
  • Track weekly average weight, not daily fluctuations

How we calculate this

Method
Mifflin-St Jeor equation
Formula
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 for men, − 161 for women
Source
Mifflin MD, St Jeor ST et al., "A new predictive equation for resting energy expenditure in healthy individuals", American Journal of Clinical Nutrition, 1990.
Limitations
Harris-Benedict (revised) and Katch-McArdle are also selectable. All three are population estimates: individual resting expenditure varies with body composition, medication and thyroid function, and none of them measure you.
Last reviewed

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Frequently Asked Questions

BMR (Basal Metabolic Rate) is the energy your body burns at complete rest — roughly 60-75% of your total daily burn. TDEE (Total Daily Energy Expenditure) is BMR plus the calories burned through activity and digestion, giving your true total daily calorie needs.

For weight loss, eat somewhere between your BMR and TDEE — never below BMR for extended periods, since that risks muscle loss and metabolic slowdown. For maintenance, eat at your TDEE, and for weight gain, eat above it.

Formula-based BMR estimates are typically accurate to within about 10% for most people. Underlying medical conditions like thyroid disorders or PCOS can shift your actual BMR by 10-30% in either direction.

Yes, but modestly — muscle tissue burns roughly 6 calories per pound per day at rest, compared to about 2 calories per pound for fat tissue. Gaining 10 lbs of muscle would raise your BMR by only around 60 calories per day.

Common reasons include having less muscle mass relative to body weight, genetic variation (roughly 10% is considered normal), an undiagnosed thyroid issue, or metabolic adaptation from a history of crash dieting.

Yes, modestly: building muscle through strength training, staying well hydrated, getting 7-9 hours of sleep per night, and eating enough protein (which has a higher thermic effect than fat or carbs) can all nudge your BMR upward over time.

Yes — losing body mass naturally lowers your BMR since there's less tissue to maintain. Sustained dieting can also trigger adaptive thermogenesis, an extra 5-10% metabolic slowdown beyond what weight loss alone would explain.

BMR typically declines by about 1-2% per decade after age 30, largely due to gradual muscle loss. Regular strength training can help preserve muscle mass and slow this decline.

Hypothyroidism can lower your actual BMR by 10-30% below what these formulas predict, since they assume normal thyroid function. If you suspect a thyroid issue, get it checked — proper medication can normalize your metabolic rate.

Yes — indirect calorimetry testing at a lab, clinic, or some gyms (typically $75-150) measures your oxygen consumption directly for a highly precise BMR figure, rather than estimating it from age, weight, and height.

Mifflin-St Jeor is the most accurate for most modern adults and is the default here. Katch-McArdle is more precise if you know your body fat percentage, especially for athletes and very muscular individuals, since it accounts for lean body mass directly.

Yes — toggle between Metric (kg, cm) and Imperial (lb, ft/in) at the top of the calculator, and all figures convert automatically.

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Your BMR
1,674
View Breakdown