Estimate daily calorie needs

You enter weight, height, age, the binary sex used by the formula, an activity rung, and a goal. The tool first estimates resting energy with Mifflin-St Jeor (1990), the resting equation HexaCalc uses as its default. It then multiplies by a factor between 1.2 and 1.9. Those factors are practical Harris-Benedict-style multipliers; they are not the individual PALs in the FAO/WHO/UNU 2004 report, which we cite as a frame for human energy needs, not as the source of 1.2–1.9. Finally a fixed offset is added or subtracted. If the total falls under 1,200 kcal, the display is clamped to 1,200 kcal: that is an interface floor, not a medically validated minimum for you.

Femme : MB = 10 × poids(kg) + 6,25 × taille(cm) − 5 × âge + (−161)

Homme : MB = 10 × poids(kg) + 6,25 × taille(cm) − 5 × âge + 5

TDEE ≈ MB × facteur d’activité (1,2 / 1,375 / 1,55 / 1,725 / 1,9)

Target = max(1,200 ; TDEE + offset)  with offset ∈ {0, −300, −500, +250, +400}

Mifflin, St Jeor et al. published a predictive equation for resting energy in healthy adults in 1990. We use it as the first brick, a common public estimator, while noting that lab REE and strict BMR are not identical. The activity factor does not come from an accelerometer or a food log: it is one of five rungs. The goal offsets (−300, −500, +250, +400) are HexaCalc design choices, not constants from Mifflin or FAO/WHO/UNU. A food deficit does not become linear fat loss; water, glycogen, and expenditure adaptation play. Linked food pages (roast chicken, cooked rice, apple) illustrate portions; they do not turn this calculator into a meal plan. Enter kg and cm; convert lb and ft/in first if needed.

Weight

Weight enters Mifflin linearly (10 kcal per kg). A morning scale weight is enough; the tool does not separate fat mass. Convert pounds before typing.

Height

Height enters at 6.25 kcal per centimeter. A 2 cm error moves BMR by about 12.5 kcal. Measure standing, without shoes.

Age

Age lowers the estimate (5 kcal per year). The accepted range starts at 15 so an adult equation is not applied to a young child.

Sex

The +5 / −161 term is not a clinical judgment: it is the 1990 equation constant from the study’s male/female groups.

Activity level

Only five rungs. “Moderately active” is not “I walked 8,000 steps” measured. Desk work plus two weekly sessions is often closer to light than to active.

Goal

Maintain copies TDEE. Other rungs apply a fixed delta, the same at 50 kg or 100 kg — another deliberate limit of the tool.

Assumptions

• Adult whose profile is closer to resting-equation populations (healthy people, not a clinical protocol).
• The activity factor describes an average lifestyle, not yesterday’s workout.
• The goal offset is a lump amount, independent of weight.
• The 1,200 kcal floor is a display rule of the tool.

Limits

• No calorimetry, no lean mass, no hormones, no medications.
• Unsuitable in pregnancy, breastfeeding, malnutrition, and many endocrine diseases.
• A very muscular athlete or a person with limited mobility can sit far from Mifflin × factor.
• The 1.2–1.9 values are not the tabulated FAO/WHO/UNU 2004 PALs.
• No food is prescribed: chicken, rice, and apple links are illustrations.

Read the result as an order of magnitude for planning, not a target to hit to the last kilocalorie. TDEE shown next to the goal is the base before the offset. If the 1,200 kcal warning appears, the raw math was lower: that is not a green light for an aggressive deficit. For expenditure without a goal, open TDEE; for rest only, BMR; to split energy, macros.

• Picking the highest activity rung “to get more calories.”

  A rung too high inflates TDEE. If unsure, step down and watch weight over several weeks rather than inventing an athlete’s day.

• Believing a 500 kcal deficit loses 0.5 kg (about 1 lb) of fat per week.

  That is a napkin rule, not physiology. The scale mixes water, gut contents, and tissue. We do not draw a loss curve.

• Using the 1,200 kcal floor as a “safe” diet.

  The floor only stops an even lower display. It does not say 1,200 kcal fits your size, health, or sport.

• Recalculating every day from the scale.

  Daily weight wiggles. A weekly recalc, or after a real lifestyle change, is enough for this estimator.

• TDEE calculatorTDEE here is Mifflin-St Jeor resting metabolism times an activity factor. It includes no deficit, no surplus, and no 1,200 kcal floor.
• Basal metabolic rateTwo resting-energy equations: Mifflin-St Jeor as the main result, revised Harris-Benedict (1984) as a comparison. No activity factor is applied.
• Macro calculatorThe tool applies an energy percent to the calories you type, then converts with 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat. These are templates, not a care plan.
• Protein calculatorThree coefficients per kilogram: the EFSA PRI 0.83 g/kg for a healthy adult, 1.2 g/kg as an internal “active” rung, 1.6 g/kg as an example in the middle of the 1.4–2.0 g/kg range often cited for training (ISSN 2017).
• BMI calculatorBody mass index is weight in kg divided by height in meters squared. Labels use adult WHO cut-offs. That is not an obesity diagnosis by itself, and it is not a child BMI.

Written by Rédaction HexaCalc (editorial team). Content last updated: August 25, 2026. No third-party medical or financial review is claimed.

• Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO — A new predictive equation for resting energy expenditure in healthy individuals (1990) — The American Journal of Clinical Nutrition
• Human energy requirements (2004) — FAO / WHO / UNU