1. Resting energy expenditure
CalorieRange uses the Mifflin-St Jeor equation to estimate resting energy expenditure. Weight is entered in kilograms, height in centimeters, and age in years.
Male: 10W + 6.25H - 5A + 5
Female: 10W + 6.25H - 5A - 161The equation was derived from 498 healthy adults aged 19-78. Like every predictive equation, it can differ from an individual's measured energy expenditure.
2. Activity adjustment
Estimated BMR is multiplied by a selected activity factor: 1.2, 1.375, 1.55, 1.725, or 1.9. Activity is usually the largest source of user-input uncertainty, so selecting the lower plausible category is often a sensible starting point.
3. Goal adjustment
Weight-loss targets use a 10%, 15%, or 20% deficit. Weight-gain targets use a 5%, 10%, or 15% surplus. The calculator does not return a target below 1,200 kcal per day. That guardrail is not a personalized medical recommendation.
4. Macro estimates
Macro grams are calculated from the selected calorie target using one of three percentage splits. Protein and carbohydrate use 4 kcal per gram; fat uses 9 kcal per gram. These splits are optional planning templates, not requirements.
5. How to use the result
Treat the result as a starting range. Track intake and weekly average weight consistently for two to three weeks. If the trend is materially different from the goal, consider a small 100-150 calorie adjustment.
Sources and limitations
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals.
- USDA National Agricultural Library DRI Calculator.
- NIH Body Weight Planner.
This tool is for generally healthy adults aged 18-80. It is not intended for pregnancy, breastfeeding, eating disorder recovery, minors, competitive athletes with specialized requirements, or people with metabolic disease.
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