Estimate daily calorie needs based on age, weight, height, gender, and activity level using Mifflin-St Jeor.
Daily calorie needs depend on both resting energy use and physical activity. This calculator applies the Mifflin-St Jeor equation to age, weight, height, and the selected male or female option, producing a resting estimate commonly labeled BMR. It then applies the chosen activity multiplier to estimate total daily energy expenditure, or TDEE. The common surprise is that TDEE estimates maintenance calories, not an automatic weight-loss target.
A concrete input and expected output from the current implementation.
Input
Male; age: 30 years; weight: 80 kg; height: 180 cm; activity: sedentary
Expected output
BMR: 1780 kcal/day; estimated TDEE: 2136 kcal/day
The male Mifflin-St Jeor calculation is 10 x 80 + 6.25 x 180 - 5 x 30 + 5 = 1780. Applying the sedentary multiplier of 1.2 gives 1780 x 1.2 = 2136 kcal/day.
The calculator inserts weight in kilograms, height in centimeters, and age in years into the Mifflin-St Jeor equation. The male form adds 5: 10 x weight + 6.25 x height - 5 x age + 5. The female form instead subtracts 161. This result represents estimated resting energy expenditure before activity is considered.
TDEE is obtained by multiplying the resting estimate by the factor assigned to the selected activity level. A higher activity selection therefore raises TDEE without changing the underlying resting calculation. The result is an estimate of average daily maintenance energy, so it should be interpreted over time rather than as an exact requirement for every individual day.
No. TDEE is an estimate of calories that would maintain current weight at the selected activity level. Weight-loss planning usually starts below that estimate, while weight-gain planning starts above it. The calculator does not establish a medically appropriate deficit or account for health conditions, so the displayed TDEE should be treated as a starting estimate.
The activity choice multiplies the entire resting-energy estimate, so even a modest change in the multiplier affects every estimated resting calorie. The categories summarize habitual movement and exercise rather than one unusually active day. If two categories seem plausible, calculate both and treat the resulting values as a practical range rather than assuming either is exact.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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