THE METHOD
How the calorie calculator works
The calculator estimates resting energy expenditure, then applies an activity multiplier to estimate total daily energy expenditure.
1. Estimate resting energy expenditure
The Mifflin–St Jeor equation estimates resting energy expenditure (often called resting metabolic rate or, informally, BMR). For adults, the equation is:
10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
The sex variable is a parameter in the published equation. The equation may not accurately represent every person.
2. Estimate total daily energy expenditure
The resting estimate is multiplied by an activity factor. This is a broad approximation: real activity and energy expenditure do not fit perfectly into fixed categories.
- Sedentary: 1.20
- Lightly active: 1.375
- Moderately active: 1.55
- Very active: 1.725
- Extra active: 1.90
3. Apply a goal adjustment
For an illustrative starting estimate, this tool subtracts 500 kcal/day for weight loss or adds 300 kcal/day for weight gain. These adjustments are not appropriate for everyone and are not guarantees of a particular outcome. The maintenance estimate is shown separately.
Limitations
These equations are population-level estimates, not direct measurements. They may be less suitable for athletes, people with unusual body composition, and people with medical or nutritional needs. The tool is for adults only and should not replace advice from a qualified clinician or registered dietitian.
References to verify before launch
Primary reference: Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition. 1990;51(2):241–247. DOI: 10.1093/ajcn/51.2.241.
Before publishing, verify the citation and consider adding links to reputable public-health guidance for any additional health claims.