BMR Calculator – Mifflin St Jeor Equation

Advanced dashboard estimates BMR, TDEE, and adaptive calorie guidance. Switch between metric or imperial units, male or female options. Customize activity factors for real-world training and lifestyle. Log profiles, compare scenarios, export concise summaries instantly. Ideal for data-driven nutrition planning and long-term transformation tracking.

Input details

Results summary

BMR
- kcal/day
TDEE
- kcal/day
Goal calories
- kcal/day
Activity factor
-
Macros suggestion
-

Goal summary: -

Example data and calculation log

Start with the example row, then add your own profiles and export.

# Gender Age Weight Height Activity factor Goal BMR (kcal) TDEE (kcal) Goal kcal Protein (g) Carbs (g) Fat (g)
1 Male 30 70 kg 175 cm 1.55 Maintain 1649 2556 2556 160 288 85

Formula used (Mifflin St Jeor Equation)

For weight in kilograms, height in centimeters, age in years:

TDEE: TDEE = BMR × activity factor.

Goal calories are derived by applying standard weekly deficits or surpluses.

What Is Basal Metabolic Rate (BMR)?

Basal metabolic rate is the minimum energy your body needs at complete rest to support vital functions such as breathing, circulation, cell repair, and organ activity over twenty-four hours.

It does not include calories burned from daily movement, exercise, stress, or digestion. Those are added through an activity factor to estimate your total daily energy expenditure.

How the Mifflin St Jeor Equation Calculates Your BMR

The Mifflin St Jeor formula uses four primary inputs: weight, height, age, and sex. Each term adjusts energy needs based on body size and metabolic slowdown with age.

This calculator converts imperial units to metric, applies the correct male or female equation, and then multiplies by your chosen activity factor to estimate daily maintenance calories.

Why the Mifflin St Jeor Formula Is Considered More Accurate

Compared with older equations like Harris–Benedict, Mifflin St Jeor was derived from more recent data and tends to track closer to measured resting energy in many adults.

It is widely used by dietitians and researchers as a default predictive model for non-clinical settings. However, it still provides estimates, not individualized metabolic testing results.

Factors That Affect Your BMR (Age, Muscle Mass, Hormones, Genetics)

Illness, extreme dieting, sleep, temperature, and body composition shifts can also influence BMR. Always seek professional guidance for medical or clinical decisions.

How Often Should You Recalculate Your BMR?

Recalculate when bodyweight, activity level, or routine changes meaningfully, such as a three to five kilogram shift or a new training phase.

For most individuals, every eight to twelve weeks works well. Athletes or those in active fat loss or bulking cycles may reassess more often to keep targets accurate.

BMR vs RMR vs TDEE: What’s the Difference?

BMR is energy used at complete rest under strict conditions. RMR is similar but measured more flexibly and slightly higher.

TDEE is total daily energy once movement, exercise, digestion, and lifestyle are included. Here, TDEE is estimated by multiplying predicted BMR by your chosen activity factor.

Mifflin St Jeor vs Harris Benedict vs Katch McArdle

Mifflin St Jeor is often preferred for modern adults due to better alignment with measured resting energy across many populations.

Harris–Benedict is older and may overestimate needs. Katch McArdle uses lean body mass and is powerful when body fat is measured accurately, especially in lean or athletic individuals.

Common Mistakes When Using a BMR Calculator

How to use this calculator

  1. Select gender and provide age, weight, and height.
  2. Choose preferred units; conversions are handled automatically.
  3. Pick your activity level or enter a custom factor when needed.
  4. Select a bodyweight goal matching your client or personal target.
  5. Choose a macro preset or input custom macro percentages.
  6. Click “Calculate BMR & TDEE” to generate detailed results.
  7. Add scenarios to the log table for comparison or client management.
  8. Export results as CSV or PDF for documentation and follow-up.

Calculations are estimates only and must not replace professional medical guidance.

Related Calculators

Pregnancy Calorie Needs CalculatorRefeed Day Calories CalculatorProtein Intake by Goal Calculatorcarb keto calculatorketo bmr calculatorketo diet weight loss calculatorketo dog calculatorketo cholesterol calculatorbee grade calculatormacro calculator keto free

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.