How this calculator works
Mifflin-St Jeor resting energy is multiplied by a conventional activity factor, then adjusted by a fixed goal amount. This is for healthy, non-pregnant, non-lactating adults. The supported age input is 15 to 100 years; the original study covered 19 to 78. Activity estimates and fixed adjustments do not account for growth, illness or metabolic adaptation. The result is an estimate for information only and is not medical advice.
Formula
Calories = Mifflin-St Jeor BMR x activity factor + goal adjustment. Adjustments: maintain 0; mild loss -250; loss -500; gain +500 kcal/day.
Worked example
At 80 kg, 180 cm and age 30, a sedentary male estimate is 2136 kcal/day. A loss adjustment gives 1636 kcal/day.
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Frequently asked questions
Is this a personalised eating plan?
No. Energy needs vary and a fixed adjustment may be unsuitable, especially at a low maintenance estimate.
Does a calorie target guarantee weight change?
No. Activity, intake measurement and metabolic changes affect the outcome.
Why does the result carry a warning?
When the goal adjustment takes the target below 1500 kcal/day for males or 1200 for females, the page flags it. The number is not raised, and the floor is not a personalised safe intake.