Calorie Calculator: Practical Guide
Estimate resting energy use, activity-adjusted maintenance calories, and a simple target for maintaining, gaining, or losing weight. Estimates apply to adults and do not diagnose health conditions.
What does a calorie calculator estimate?
Your body uses energy to maintain vital functions and power daily activity. Basal metabolic rate (BMR) estimates resting energy requirements. Total daily energy expenditure (TDEE) applies an activity multiplier to BMR to approximate maintenance calories. A target above or below maintenance is a planning estimate, not a medically prescribed diet. The calculator does not use body-fat percentage or measure metabolism directly.
How to use the Calorie Calculator
- Enter your weight in kilograms, height in centimeters, and adult age (18–120 years).
- Select the sex used for the Mifflin–St Jeor prediction equation. This is a parameter in the published formula, not a measure of gender identity.
- Choose the activity multiplier that most closely reflects your average routine.
- Choose maintain, loss, or gain to see maintenance energy and an illustrative target.
- Recheck the estimate when your routine, body weight, or training changes.
BMR and TDEE formulas
The Mifflin–St Jeor estimates are:
- Male equation:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) + 5 - Female equation:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) − 161 - Maintenance estimate:
TDEE = BMR × activity multiplier
The tool offers common factors: 1.2, 1.375, 1.55, 1.725 and 1.9. Its loss/gain modes subtract or add 300 kcal/day, an illustrative—not personalized—adjustment.
Worked example: 70 kg, 170 cm, age 30
Using the male equation, BMR = 700 + 1062.5 − 150 + 5 = 1617.5 kcal/day. With an activity factor of 1.55, estimated maintenance is 1617.5 × 1.55 = 2507.125 kcal/day. Rounded, that is 2,507 kcal/day. A displayed illustrative loss target would be about 2,207 kcal/day and a gain target about 2,807 kcal/day. These outputs are estimates, not guaranteed changes in body weight.
Choosing an activity factor
An activity multiplier combines movement, work, and exercise; it is not just the duration of a workout. Someone training three times a week but sitting most of the day may have lower total expenditure than expected. Select the factor conservatively and use longer-term observations to assess whether the estimate is useful. The calculation does not account separately for pregnancy, lactation, growth during childhood, illness or unusual metabolic circumstances.
Limitations and practical interpretation
A calorie estimate is not a measured requirement. Food labeling, activity-tracker readings, and individual metabolism all introduce uncertainty. Do not use the tool as a calorie prescription for children, pregnancy, eating-disorder recovery, or clinical nutrition. For specific medical or nutritional needs, consult an appropriately qualified professional. The calculator updates locally as inputs change and does not convert energy units or currencies.
Frequently asked questions
The expandable FAQ section above addresses common usage and interpretation questions. Check the calculator inputs, formula and limitations before using results for important decisions.