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Calorie and basal metabolic rate calculator

Fill in five details and pick your goal: you will see your daily calories and a suggested split of protein, fat and carbs. It is an estimate using a published equation, not a clinical measurement.

Privacy: what you type stays in your browser and is not sent to any server. To remember your ticks and your data, this page uses your device’s local storage (it does not use cookies). You can delete it whenever you like. What is stored and how to delete it

How it works and where the data comes from

How it is calculated

  1. Basal metabolic rate with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men or − 161 for women.[1] In a systematic review it was the commonly used equation most likely to land within 10% of the measured value, but the error for a given person can be larger.[2]
  2. Daily use = basal metabolic rate × activity level. We use 1.40, 1.55, 1.75, 1.95 and 2.20, within the FAO/WHO/UNU physical activity level categories.[3]
  3. Goal: maintain (±5%), lose gradually (10 to 20% below, never below the basal metabolic rate) or gain gradually (5 to 15% above). These are this tool’s criteria, not a prescription.
  4. Suggested macros: protein from 1.4 to 2.0 g per kilogram, fat at about 28% of energy (the reference range is 20 to 35%) and carbohydrates for the rest.[4][5]

Limits and warnings

For adults aged 18 to 80 only. No equation knows how much your body really moves: use the result as a starting point and adjust it according to how your weight changes over a few weeks. The review itself warns of noteworthy errors for some individuals and of little validation in older adults and some ethnic groups.[2]

The tool does not suggest deficits below your basal metabolic rate and warns you when BMI, age or other data suggest talking to a professional. If you are pregnant, have an illness or an eating disorder, do not use this calculator without checking with a health professional.

What you type never leaves your browser. It is only remembered on this device if you tick the box under “More options”. The button that uses the result as your goal saves only your calories and protein, to show them in the macro calculator.

Frequently asked questions

Why does my result change with activity?
Because daily use is the basal rate multiplied by an activity factor. Choose the one that best describes your typical week, not your best week.
Is it exact?
No. It is an estimate: in a systematic review, this equation was the one most often within 10% of the measured value, but the error for a given person can be larger, and the activity factor adds more uncertainty. Adjust using how your weight changes over two to four weeks.
Is it suitable for under 18s?
No. If you are under 18, talk to a health professional; energy needs during growth are different.

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Sources (5)

  1. Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. doi:10.1093/ajcn/51.2.241
  2. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789. doi:10.1016/j.jada.2005.02.005
  3. FAO. “Human energy requirements: report of a Joint FAO/WHO/UNU Expert Consultation (Rome, 17-24 October 2001). FAO Food and Nutrition Technical Report Series 1. Rome: FAO; 2004”. Accessed October 16, 2026. www.fao.org/4/y5686e/y5686e00.htm
  4. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. doi:10.1186/s12970-017-0177-8
  5. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academies Press; 2005. doi:10.17226/10490

Date this page was reviewed: October 20, 2026. If you spot a mistake, let us know from the contact page.

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Informational content for healthy adults: it is not medical advice or a personalized diet or training plan, and it does not replace a health, nutrition or training professional. Health notice. If you are a rights holder and want to raise a claim, see the methodology or write from the contact page.