Calorie Calculator

Mifflin–St Jeor estimates resting energy: 10 × kg + 6.25 × cm − 5 × age, plus 5 for the male equation or minus 161 for the female equation. An activity multiplier estimates total daily needs.

For the male equation at 30 years, 80 kg and 180 cm: resting energy is 1,780 kcal/day. At an activity factor of 1.2 the estimate is 2,136 kcal/day.

The activity multiplier is an assumption. Compare the estimate with several weeks of observed weight and intake rather than treating the displayed value as an exact prescription.

Adult population estimates are not individualized diet advice. Pregnancy, adolescence, illness, medications and athletic training can require professional assessment.

The resting-energy estimate and the daily-expenditure estimate answer different questions. The first applies the Mifflin–St Jeor equation to the entered age, height, weight and selected male or female equation. The second multiplies that estimate by an activity factor. Neither is a direct measurement of your metabolism. The calculator does not observe your exercise, record food or measure energy use; it applies a population equation and the assumptions you select.

Use the unit system that matches your measurements. Metric height is entered in centimeters, while imperial height uses separate feet and inches. Weight must match the selected kilograms or pounds setting. The age entry is for adults from 18 to 120, but acceptance by the form does not establish that the equation is suitable for every person within that range. Pregnancy, illness, medications and other circumstances can require an individualized assessment.

Read the activity descriptions before selecting a factor. A demanding workout on one day does not necessarily describe your overall routine, just as a desk job does not tell the whole story about activity outside work. The activity setting is a broad assumption about daily expenditure, not a score for effort. If two descriptions seem plausible, compare the resulting estimates and recognize the uncertainty rather than choosing whichever number best matches a desired calorie allowance.

With the male equation, age 30, weight 80 kilograms and height 180 centimeters produce a resting estimate of 1,780 kcal per day. An activity factor of 1.2 gives 2,136 kcal per day. Keeping everything else unchanged but entering age 40 lowers the resting estimate to 1,730 and the expenditure estimate to 2,076. This demonstrates the equation's age term; it does not predict how one particular person's metabolism will change over ten years.

The calculator shows the daily-expenditure estimate minus 500 and plus 500 kcal. With the 2,136 example, those numbers are 1,636 and 2,636. They are generated by subtraction and addition, not by checking nutritional adequacy, medical history or a personal weight-management plan. The lower number is not automatically a safe intake recommendation, and the higher number is not automatically suitable for building muscle. No minimum-intake rule or clinical suitability assessment is applied.

A fixed difference between estimated expenditure and intake also does not guarantee a particular weekly weight change. Appetite, actual activity, fluid changes and energy expenditure can change over time. The tool does not model those responses. If a lower arithmetic scenario is implausibly small or not meaningful, do not try to make it a diet target. A clinician or registered dietitian can assess circumstances that cannot be represented by the few fields in this form.

Treat it as a starting estimate with known inputs, not a precise daily requirement. If tracking intake or weight is appropriate for your circumstances, trends over time can provide context that a single equation cannot. Do not judge the estimate from one unusual day or one scale reading. The calculator does not prescribe a tracking routine, and people with an eating-disorder history or other relevant health concerns may need a different approach with professional support.

Keep the assumptions alongside any figure you save. An expenditure estimate without its activity setting is easy to misinterpret later. Recheck obvious input errors before comparing it with another calculator, and note whether that other tool uses a different equation or multiplier. A disagreement does not mean that the larger value is more accurate. This page is designed to make one calculation understandable; it cannot diagnose metabolic problems, prescribe nutrition or replace a measured or individualized assessment.