Method choices
The calculator uses Mifflin-St Jeor as the default adult BMR equation, shows revised Harris-Benedict for comparison and adds Katch-McArdle when a body-fat estimate is available. Comparing methods can show why calorie estimates are ranges, not exact personal targets.
Example
For a 35-year-old adult, 175 cm tall and 70 kg, the calculator estimates BMR first, then multiplies by the selected activity level to estimate daily energy needs. A goal of -0.25 kg per week is shown as a modest calorie-deficit scenario, not a prescription.
Common mistakes
Do not treat the output as an exact target. Activity level is the largest judgment call, and wearable calorie estimates, training load, illness, pregnancy and medications can change real needs.
Assumptions and limitations
This adult estimate uses a population equation and broad activity multipliers. Individual needs can differ because of body composition, health conditions, medications, adaptive metabolism, pregnancy, breastfeeding and training load. A goal expressed in kg per week is converted using a rough 7,700 kcal per kg assumption, so read it as a planning example rather than a prescription.
References
- EFSA: Dietary Reference Values for energy, accessed 2026-05-13.
- NIH/NIDDK Body Weight Planner, accessed 2026-05-13.
- NCBI Bookshelf: Mifflin-St Jeor equation, accessed 2026-05-13.
Last reviewed: 2026-05-14