BMR & Calorie Calculator
Estimate Basal Metabolic Rate and daily calorie needs from age, sex, height and activity.
Written by Rahman · Last reviewed
Quick answer
Basal metabolic rate is estimated here with the Mifflin-St Jeor equation: for men, 10 × kg + 6.25 × cm − 5 × age + 5; for women the same with −161 in place of +5. Multiplying BMR by an activity factor gives total daily energy expenditure. These are population averages; an individual's actual rate commonly sits around 10% either side of the estimate.
- Basal metabolism (at complete rest)1,669.00 (64.5%)
- Activity and digestion918.00 (35.5%)
- kcal/day2,587.00
Maintenance calories are what the Mifflin-St Jeor equation estimates you burn in a day at the activity level selected — the level at which weight tends to hold steady. It is an estimate for a population, and individual needs vary by 10% or more either side of it. Any decision to eat above or below maintenance is one to make with a doctor or registered dietitian who knows your history.
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Results are general screening estimates, not medical advice or a diagnosis. They can read inaccurately for athletes, older adults, children and during pregnancy. Speak to a doctor or registered dietitian before changing your diet, exercise or medication.
About the BMR & Calorie Calculator
Your Basal Metabolic Rate (BMR) is the energy your body uses at complete rest to keep essential functions running. Total daily calorie need adds the energy burned through daily activity and exercise to that baseline.
This calculator uses the well-established Mifflin-St Jeor equation to estimate your BMR and your maintenance calories.
Men: BMR = 10×kg + 6.25×cm − 5×age + 5 Women: BMR = 10×kg + 6.25×cm − 5×age − 161
Daily calorie need is BMR multiplied by an activity factor from 1.2 (sedentary) to 1.9 (very active).
What a calorie estimate can and cannot tell you
The Mifflin-St Jeor equation was derived by regression against measured resting energy expenditure in healthy adults. It is the best-validated of the simple predictive equations, and it is still a population average applied to an individual.
- Individual resting rates commonly sit around 10% either side of the prediction, and further out at the extremes of body composition.
- The equation uses weight, height, age and sex. It cannot see muscle mass, and muscle is more metabolically active than fat, so it under-predicts for very lean, muscular people.
- Activity multipliers are coarse. The gap between the sedentary and moderate factors is roughly 30%, and most people place themselves optimistically.
- Thyroid conditions, some medications and a history of significant weight loss all shift actual expenditure away from the prediction.
Treat the output as a starting estimate to be adjusted against what actually happens over several weeks, rather than a measured quantity. If you have a medical condition affecting metabolism or are making significant dietary changes, a doctor or registered dietitian is the right place to take this.
Frequently Asked Questions
What are maintenance calories?
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Maintenance calories are the daily intake that keeps your weight stable: your BMR multiplied by an activity factor.
What is a calorie deficit or surplus?
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A deficit is eating fewer calories than your maintenance figure above; a surplus is eating more. This calculator reports your estimated maintenance level only. It does not recommend a specific deficit, surplus or timeline, since a safe, appropriate amount depends on individual health factors best discussed with a doctor or registered dietitian.
How accurate is this estimate?
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The Mifflin-St Jeor equation is one of the most reliable formulas, but individual metabolism varies. Use the result as a starting point and adjust based on real results.
Should I eat below my BMR?
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Eating well below your BMR for long periods is generally not advisable. Consult a healthcare professional or dietitian before making large dietary changes.
Sources
- Mifflin MD et al., Am J Clin Nutr 1990 — A new predictive equation for resting energy expenditure — The paper that derived the BMR equations this calculator uses.