About Calories & Macros
A free, science-based nutrition calculator built for people who want clear, honest estimates — without paywalls or required sign-ups.
What this tool does
Calories & Macros calculates your estimated daily calorie needs based on your age, height, weight, sex, activity level, and goal. It then splits those calories into protein, carbohydrates, and fat using goal-specific ratios backed by nutrition research. Beyond the main calculator, the site includes 10 additional calculators for body composition, hydration, pregnancy, children's nutrition, and exercise, plus reference tables and guides covering foods, restaurants, and popular diets.
Who's behind this site
Calories & Macros is an independent project, not affiliated with any supplement brand, gym chain, or diet program. It's built and maintained by a small team with a background in software development and a personal interest in evidence-based nutrition and fitness — not registered dietitians or physicians. We are not a substitute for personalised medical or nutritional advice, and we say so clearly throughout the site rather than implying credentials we don't have.
Our methodology and sources
Every formula and figure on this site is drawn from published research and recognised health authorities rather than invented or guessed at. Some of the key sources behind our calculators:
- Calorie & BMR calculations: Mifflin ST et al., 'A new predictive equation for resting energy expenditure in healthy individuals' (American Journal of Clinical Nutrition, 1990)
- Protein recommendations: International Society of Sports Nutrition position stand on protein and exercise
- Vitamin & mineral RDAs: U.S. National Academies of Sciences, Engineering, and Medicine, Food and Nutrition Board
- Body fat estimation: U.S. Navy circumference-based method
- Pregnancy nutrition: American College of Obstetricians and Gynecologists (ACOG) and WHO guidance
- Food and restaurant nutrition data: USDA FoodData Central and official restaurant-published nutrition information
Where a topic is genuinely unsettled in the research (like the ideal diet for weight loss, or exact ranges for optimal macros), we say so explicitly rather than presenting one view as universal fact. Each calculator page includes a methodology section explaining exactly how the numbers are derived and where the approach has limitations, so you can judge how much weight to put on the result.
How we keep this site accurate
We periodically review calculators and reference tables against current guidance from bodies like the WHO, NIH, and USDA, and update figures when official recommendations change. If you spot an error, an outdated figure, or a source you think we've misrepresented, we genuinely want to know — please use the contact page below to flag it.
Who this is for
- People starting a fat loss or muscle gain phase who need a calorie and macro target
- Athletes and gym-goers who want to cross-check their current intake
- Beginners learning about nutrition who want a clear educational starting point
Important disclaimer
The results produced by this calculator are estimates based on population-average formulas. The information provided here is for educational purposes only and does not constitute medical or nutritional advice. If you have a health condition, please consult a qualified healthcare professional before changing your diet.
Contact
Have a question or found a bug? Visit our contact page.