Calorie and macro calculator: understand the estimate

Use the calculator with context

Enter age in years, height in centimetres and weight in kilograms. Decimal points and decimal commas are accepted. Select the sex category used by the equation, an approximate activity category and the goal used for the calculation. The arithmetic runs on the device.

The sex-specific coefficients describe how the original prediction equation was constructed; they are not a complete account of individual physiology. The tool does not resolve all circumstances, including pregnancy, breastfeeding, medical conditions, relevant treatment or a history of disordered eating. Seek individual support rather than treating the output as a prescription.

Resting expenditure: what is being predicted?

The simplified equation uses 10 × body mass in kg + 6.25 × height in cm − 5 × age in years, then +5 for the male category or −161 for the female category. The original study measured resting energy in healthy adults aged 19–78. It did not construct a prediction for children, pregnancy or every athlete population.

The page uses resting expenditure as the meaning behind the familiar basal-metabolism label. Strict basal and resting measurement conditions are not identical, and neither value alone represents an entire day’s energy expenditure.

The equation review found individual prediction errors even among the better-performing equations. A criterion of being within 10% in a validation study is not a guarantee for your individual resting value or for the final daily result.

The activity multiplier adds another estimate

The tool multiplies the resting estimate by a selected factor. Session counts in the labels are rough prompts; occupation, transport, non-exercise movement and the intensity and length of sessions can change what fits.

How the goal range is produced

For the fat-loss option, this tool subtracts 300–500 kcal from its estimated daily expenditure; for the muscle-gain option, it adds 200–400 kcal. Maintenance uses the estimated expenditure without that adjustment. These ranges are calculation choices, not doses established by the resting-equation papers.

The algorithm stops the range from falling below predicted resting expenditure and rounds displayed values. That floor is a tool convention, not a clinical minimum or proof of an appropriate intake. A result at the floor is not an instruction to increase activity to force a larger deficit.

This general-purpose tool does not show a calorie target or macro split if the lower end of the proposed range is 1,200 kcal/day or less, either before the resting floor or after display rounding. It refuses the result instead of replacing it with 1,200 kcal. This scope exclusion is not a minimum recommended intake, and a result above it is not a guarantee of suitability.

Review the estimate alongside a longer trend and relevant circumstances rather than one weigh-in. Do not treat weight fluctuations as exact changes in body fat or assume that everyone should pursue a weight-change target.

How protein, fat and carbohydrate are assigned

The tool uses 2 g/kg for protein in its fat-loss option and 1.8 g/kg otherwise. Fat starts from 0.9 g/kg or an energy reference of 20%, whichever is higher before rounding. Carbohydrate takes the remaining energy. These are illustrative settings for a resistance-training context, not the needs of every adult.

Above the tool’s BMI reference, protein and fat use the lower of entered body mass and the mass corresponding to BMI 25 at the entered height. That reference is a calculation convention, not a target weight, diagnosis or recommended weight loss. It does not change the mass used in the resting equation.

The protein synthesis concerns healthy adults doing resistance training. Its average breakpoint is not everyone’s exact need, and it does not validate this entire calculator, its activity factors or its reference-weight rule.

The ISSN protein position stand concerns healthy exercising people; it does not validate a single intake for sedentary adults, illness or every older adult. Protein here means the total from food and any supplements, not an extra supplement dose.

EFSA reference ranges describe population nutrition, not the validation of this macro algorithm. This split may fall outside those ranges and does not assess fibre, essential fatty acids, vitamins, minerals or food quality. A complete eating pattern needs a separate assessment.

Reference: Morton et al. · 2018 ↗Jäger et al. · 2017 ↗EFSA · 2017 ↗

Input limits and appropriate support

The form accepts ages 18–80, heights 140–220 cm and weights 40–200 kg. These are software input bounds, not proof that predictions are validated equally across that entire rectangle. Outside them the tool asks you to check the inputs rather than returning a number.

The tool also withholds every calorie and macro result below its BMI screening reference of 18.5. This scope exclusion directs the reader towards an individual assessment; it does not diagnose malnutrition or identify a weight to reach. A result at or above this reference is not proof that nutrition support is unnecessary.

NICE guidance places low-energy and very-low-energy diets within supported specialist care. This tool does not provide that care. If no result is shown, check the entries and seek individual advice rather than changing the entries to force a target.

For a medical condition, pregnancy, breastfeeding, relevant treatment, significant symptoms or a history of disordered eating, use appropriate individual advice before changing intake. A macro table is not a treatment plan.

If your aim includes strength practice, the programme collection provides example training structures. The walking guide explains why a step count is not an exact calorie measurement.

Reference: NICE · NG246 · 2025 ↗NICE · CG32 ↗