Formulas, assumptions, and limitations

The TDEE calculator first estimates basal metabolic rate with the Mifflin-St Jeor equations. It uses weight in kilograms, height in centimeters, age in years, and the selected sex field:

Estimated TDEE is the rounded BMR multiplied by the selected activity factor:

The activity selection is subjective and can be the largest source of error. The result is an estimate of average daily energy use, not a direct metabolic measurement.

The macro calculator uses the entered or estimated TDEE. Its current goal adjustments are TDEE minus 500 calories for weight loss, TDEE for maintenance, and TDEE plus 300 calories for weight gain.

The tool blocks a weight-loss example when subtracting 500 would produce a value below its 1,200-calorie planning guardrail. It does not silently replace that requested scenario with a different deficit.

It then applies the selected fixed macro ratio and converts protein and carbohydrate calories at 4 calories per gram and fat calories at 9 calories per gram. The available presets are starting points, not individualized requirements.

The calorie-deficit calculator converts the selected weekly loss rate using approximately 7,700 calories per kilogram, divides that amount by seven, and subtracts the resulting daily deficit from estimated TDEE. Its timeline divides the weight difference by the selected weekly rate.

The current implementation blocks a scenario when its calculated target would fall below the tool's 1,200-calorie planning guardrail. That product limit is not a personalized safety determination, and the arithmetic assumes a steady rate that real weight change rarely follows exactly.

The walking calculator estimates intensity from walking speed and incline. Flat-walking values are interpolated from a stored MET table. For an incline, the implementation also calculates oxygen cost from speed and grade and uses the higher resulting estimate.

Distance and duration are derived from the chosen speed. Step conversion currently assumes 2,000 steps per mile. The MET formula produces an estimated total energy cost for the activity period, not a personalized measurement of net active calories above rest.

• The TDEE-based tools accept ages 18 through 100 and are not designed for children.
• Manual-TDEE modes require confirmation that the user is at least 18.
• Accepted inputs are 20 to 320 kg for weight, 90 to 275 cm for height, and 0.05 to 1 kg per week for the loss-rate control.
• TDEE planning inputs must be between 1,200 and 10,000 calories per day. The TDEE estimator can display a lower equation output because an energy-expenditure estimate is not an intake recommendation.
• Outputs depend on the accuracy and meaning of the entered values.
• Population equations cannot capture every difference in body composition, health, medication, fitness, terrain, or metabolism.
• Rounding and fixed assumptions make the result easier to use but less precise.
• Projected dates and rates are planning illustrations, not guarantees.

• Mifflin et al. (1990), predictive equation for resting energy expenditure
• National Institute of Diabetes and Digestive and Kidney Diseases Body Weight Planner, which uses a dynamic adult model rather than Kalo's simplified linear timeline
• 2024 Adult Compendium of Physical Activities

The activity multipliers, fixed goal adjustments, 7,700-calorie-per-kilogram conversion, input bounds, and 1,200-calorie guardrail are transparent product assumptions. They should not be interpreted as individualized clinical recommendations or as conclusions established by the references above.