Method guide
How this TDEE calculator works—and where it can be wrong
TDEE is not something a basic equation can measure. This calculator estimates resting energy, multiplies it by a broad activity category, and gives you a starting experiment. The useful part is the transparent method and the calibration process, not the single headline number.
1. Estimate resting energy
The primary result uses the Mifflin–St Jeor equation. It was developed from measured resting energy expenditure in 498 adults and uses body weight in kilograms, height in centimeters, age, and one of two sex coefficients.
| Method | Equation | How it is used here |
|---|---|---|
| Mifflin–St Jeor | 10w + 6.25h − 5a + s | Primary midpoint; s is +5 or −161. |
| Revised Harris–Benedict | Separate published coefficients for the two equation settings | Shown beside the primary result as a model comparison. |
The formulas supply male and female coefficients only. The labels are an equation limitation, not a statement about anyone’s identity. Neither formula directly measures your metabolism.
2. Apply an activity multiplier
The calculator multiplies the Mifflin resting estimate by the selected factor: 1.2, 1.375, 1.55, 1.725, or 1.9. These familiar categories are a shortcut, not part of the original Mifflin study. Jobs, step counts, training volume, and individual movement can differ substantially inside the same label, so activity selection is often the largest uncertainty.
That is why the result shows a deliberate ±15% planning band. The band is not a published confidence interval; it is an honest visual reminder to test the midpoint rather than obey it.
3. Calibrate with your own trend
Hold the plan reasonably steady for at least two to three weeks. If scale tracking is useful and comfortable for you, compare weekly averages gathered under similar conditions instead of reacting to a single day. Also pay attention to hunger, training performance, recovery, and adherence. Then adjust gradually.
The optional timeline uses the simple 3,500-kcal-per-pound arithmetic rule so the slider remains intuitive, but real weight change is dynamic. Energy expenditure and the composition of lost or gained weight change over time. For a more detailed scenario, use the official NIH/NIDDK Body Weight Planner.
4. Understand the macro template
The current training-oriented template assigns protein first (2.2g/kg of body weight, or 2.4g/kg while cutting), then fat at 1g/kg, with carbohydrate filling the remaining calories. Those are high-protein planning choices—not minimum requirements. The International Society of Sports Nutrition position stand reports that 1.4–2.0g/kg/day is sufficient for most exercising adults, with context-specific exceptions.
Food comes first. Build most meals from a varied mix of beans, lentils, soy foods, eggs, dairy, seafood, poultry, or lean meat; fruits and vegetables; grains or other starchy foods; and sources of unsaturated fat. A powder is a convenience product, not a requirement. The USDA’s Protein Foods guidance gives practical whole-food examples.
Worked example
For a 35-year-old woman at 165 lb and 65 in who selects the 1.55 activity factor, Mifflin–St Jeor estimates about 1,444 resting kcal/day and a 2,239-kcal maintenance midpoint. Revised Harris–Benedict estimates about 1,500 resting kcal/day—already a 56-kcal difference before activity is applied. The calculator’s maintenance macro template rounds to about 165g protein, 75g fat, and 226g carbohydrate. Those outputs are reproducible arithmetic, but the person still has to calibrate the calorie midpoint in real life.
