Why Do Calorie Calculators Give Me Different Numbers?

Two calorie calculators can disagree because they use different resting equations, activity factors, units or goal adjustments. A comparison is useful only when all those assumptions are explicit. DigiCalc uses one resting equation, Mifflin-St Jeor, then applies a preset multiplier; it does not claim that this is a direct measurement or the best formula for every individual.

Hold the inputs constant

For the female formula at age 35, 72.7 kg and 165 cm, the resting estimate is 1422.25 kcal/day. Every row below uses that same resting value. Only the activity assumption changes.

The light and moderate presets differ by 0.175 times the same resting estimate, or about 249 kcal/day. That difference comes entirely from a chosen multiplier; it is not evidence that one calculator measured metabolism more accurately.

Compare like with like

• Check whether the displayed number is resting energy, total daily expenditure or a goal-adjusted intake.
• Use the same age and formula sex, and check kilograms versus pounds and centimeters versus inches.
• Record the actual activity multiplier, not only a descriptive label.
• Check whether an adjustment has already been subtracted and whether the tool silently applies an intake floor.
• Keep intermediate calculations unrounded; compare rounded results only at the end.

A resting equation based on height, weight and age differs from one requiring measured lean mass. Different equations have different inputs and assumptions. DigiCalc does not offer a formula selector or establish that an estimated circumference body-fat percentage is accurate enough to substitute for a clinical body-composition measurement.

No formula is a weight-loss calendar

Knowing which assumptions produce a number does not establish a safe food intake or an exact weight-change timetable. Subtracting a daily amount from estimated TDEE is an arithmetic illustration, not a prediction of constant weekly loss. The calorie-estimate guide explains that distinction.

The Calorie Calculator is an adult illustration, not a pediatric, pregnancy or breastfeeding nutrition tool. Personal health circumstances and eating-disorder history need individualized guidance. This guide does not recommend repeated self-experimentation with restriction or establish a universal formula error margin.

Sources and Scope

Technical example checks are not independent professional review. Sources were checked for the statements above on October 6, 2026.

• Mifflin et al. (1990), resting energy equation, PMID 2305711
• Body Weight Planner: scope and limitations