Useful calculators
Estimate how much energy your body uses at rest and throughout a typical day.
This calculator estimates your resting energy expenditure and total daily energy expenditure, helping you understand the difference between the energy your body uses at rest and the calories you may need to maintain your current bodyweight.
All results are estimates, not exact measurements.
2. Understand your results
Resting metabolic rate is the energy your body uses at rest to maintain essential functions such as breathing, circulation and temperature regulation. It does not represent your total daily calorie requirements.
Although this is often called BMR, the Mifflin–St Jeor equation estimates resting metabolic rate or resting energy expenditure, which is not technically identical to measured basal metabolic rate.
Total daily energy expenditure includes resting energy expenditure, energy used during digestion and food processing, planned exercise, and everyday movement and non-exercise activity.
TDEE is the more relevant starting point when estimating maintenance calorie intake.
Your gym routine is only part of your overall activity. Someone with a physically demanding job may expend considerably more energy than someone with a desk job, even if they complete the same number of gym sessions.
The multipliers are estimates and may overestimate or underestimate an individual’s expenditure.
Context matters
As bodyweight changes, energy requirements generally change. Muscle and other body tissues contribute to resting energy expenditure.
Changes in walking, occupational activity, household tasks and general movement can alter total energy expenditure.
Changes in training frequency, duration and intensity influence energy expenditure, although the impact varies between individuals.
Digesting and processing food requires energy. The amount varies with total intake and food composition.
During sustained weight loss, energy expenditure can decrease due to changes in body size and, sometimes, additional physiological adaptations.
Age, body composition, physiology, health circumstances and variation in daily routines can affect how closely an equation reflects someone’s actual expenditure.
3. How to apply this
Your estimated maintenance calories are a starting point rather than a fixed number.
If you’re aiming to maintain your bodyweight, monitor your average weight over several weeks while keeping your calorie intake and activity reasonably consistent.
If your average weight remains relatively stable, your intake may be close to your actual energy expenditure.
If your weight consistently changes, your actual calorie requirements may differ from the estimate.
If you’re aiming to lose or gain weight, use the Weight Change Calculator to explore how your planned calorie intake compares with your estimated maintenance requirements.
Reassess your estimate when your bodyweight, activity levels or daily routine change. Use average bodyweight trends rather than reacting to individual weigh-ins.
4. Method and further reading
The Mifflin–St Jeor equation estimates resting energy expenditure from population data. For males: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5.
For females: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161.
The calculator then multiplies this resting estimate by the selected activity multiplier to provide an approximate TDEE. Neither figure is a direct measurement of your metabolism, and results can differ from actual energy requirements.
The activity multipliers are practical approximations; they are not part of the original Mifflin–St Jeor study.
Further reading: Mifflin MD et al. (1990). “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition.
For general adult educational use. Estimates may not be appropriate during pregnancy or breastfeeding, for people under 18, or for individuals whose medical circumstances require specialist nutritional guidance. This calculator does not provide medical advice or a personalised dietary prescription.
