BMR Calculator

What this calculator estimates

Estimate resting energy needs using the adult Mifflin–St Jeor equation. The main result is resting energy, while the three smaller comparisons apply fixed activity multipliers.

Inputs and calculation method

Enter age in years, height in centimetres, weight in kilograms and the male or female equation option. The form has no activity selector: it displays light, moderate and very active comparisons together.

Formula and units

Estimated resting kcal/day = 10 × weight + 6.25 × height − 5 × age + 5 for the male equation, or − 161 for the female equation. The additional comparisons multiply this estimate by 1.375, 1.55 and 1.725. Results are rounded to whole dietary Calories (kcal).

How to use it

1. Enter age in years, height in cm and weight in kg.
2. Select the equation option shown in the form.
3. Calculate and distinguish the main resting estimate from the activity comparisons.
4. Use the TDEE calculator if you want to select an activity level explicitly.

Worked example

For age 35, 165 cm, 70 kg and the female equation, resting energy is 700 + 1,031.25 − 175 − 161 = 1,395.25 kcal/day, displayed as 1,395. The light, moderate and very active comparisons are 1,918, 2,163 and 2,407 kcal respectively.

How to read the result

Although labelled BMR, this equation predicts resting energy expenditure; it does not perform a laboratory basal-metabolism test. The main number excludes the activity multipliers and should not automatically be used as an eating target.

Common mistakes

• Using BMR and TDEE as if they measured the same thing.
• Adding exercise calories to an activity-adjusted figure without checking for double counting.
• Assuming the equation directly measures metabolism.

Method limitations

Mifflin–St Jeor was developed using adults. Its predictions can differ from measured resting expenditure, and it does not account fully for individual physiology, pregnancy or clinical needs. The available equation options are formula inputs rather than a complete description of physiology.

Sources and method references

• Mifflin–St Jeor original equation

Supporting guides

• What Is BMR? The Resting Metabolism Baseline ExplainedA clear guide to basal metabolic rate, what it measures, what it leaves out, and how to use the BMR calculator before setting calorie targets.
• How To Use BMR For Weight Loss Without Cutting Too HardUse BMR correctly for weight loss by turning it into TDEE first, setting a moderate deficit, and checking progress against real-world trends.
• BMR Formula Explained: Why Age, Height, Weight And Sex MatterA practical explanation of BMR formulas, why the inputs matter, and why predictive equations should be treated as estimates rather than exact metabolism te…
• Why BMR Changes With Age And What To Do About ItLearn why estimated BMR usually shifts with age, what is normal, and how training, muscle, movement and dieting history affect the number.
• BMR vs Resting Metabolic Rate: What Is The Difference?Understand the practical difference between BMR and resting metabolic rate, why most calculators estimate rather than measure, and which number matters for…
• BMR Mistakes That Skew Calorie TargetsThe common errors that make BMR estimates misleading, including old body weights, wrong activity assumptions, aggressive dieting and confusing BMR with mai…

Using the estimate

Use the main output to understand estimated resting needs, and keep the activity comparisons separate. The equation predicts rather than measures energy expenditure.