BMR Calculator Guide: Formula & Worked Example
Short answer
Basal Metabolic Rate by two scientific formulas. In the fixed example below, bmr (mifflin-st jeor) is 1,649 kcal/day. Your answer depends on the inputs and assumptions you choose.
Formula
Result = BMR Calculator calculation using gender, age, weight, height
The inputs are gender, age, weight, height. Use the input scale shown beside each field and keep time periods and units consistent. Only round the final result for display.
Worked example
- Gender
- m
- Age
- 30
- Weight
- 70
- Height
- 175
- BMR (Mifflin-St Jeor): 1,649 kcal/day
- BMR (Harris-Benedict): 1,696 kcal/day
Understanding the result
Basal Metabolic Rate by two scientific formulas. Start with the base example, then replace each value with the figure that matches your situation.
Gender
The example uses Male for gender. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Age
The example uses 30 years for age. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Weight
The example uses 70 kg for weight. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Height
The example uses 175 cm for height. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
What the comparison means
The comparison changes only age, keeping every other example input fixed. This isolates that input's effect on the primary result. It does not predict future outcomes.
This is a screening or planning estimate, not a diagnosis. Age, pregnancy, medication and individual medical history can change how the result should be interpreted.
Comparison
| Scenario | Input | Result |
|---|---|---|
| Lower input | Age: 24 years | BMR (Mifflin-St Jeor): 1,679 kcal/day |
| Base example | Age: 30 years | BMR (Mifflin-St Jeor): 1,649 kcal/day |
| Higher input | Age: 36 years | BMR (Mifflin-St Jeor): 1,619 kcal/day |
Common mistakes
- Using the wrong units for age.
- Comparing results while changing more than one input at a time.
- This is a screening or planning estimate, not a diagnosis. Age, pregnancy, medication and individual medical history can change how the result should be interpreted.
Checklist
- Confirm gender.
- Confirm age is expressed in years.
- Confirm weight is expressed in kg.
- Confirm height is expressed in cm.
- Check the result against your source or provider.
Calculators Percentage Editorial Team
Calculator guides from the Calculators Percentage team. These introductory examples are educational, not professional advice.
Last reviewed:
This is a screening or planning estimate, not a diagnosis. Age, pregnancy, medication and individual medical history can change how the result should be interpreted.