About Macro Calculator

Calculate macronutrient ratios (protein, carbs, fat) for different dietary goals. Part of the DevTools Surf developer suite. Browse more tools in the Calculators collection.

Use Cases

• Calculate personalized macros for a fat loss, muscle gain, or body recomposition goal.
• Estimate the macro split needed to maintain current weight given an activity level.
• Compare different diet frameworks (keto, paleo, Mediterranean, flexible dieting) on a macro basis.
• Plan macros for an endurance athlete with high carbohydrate requirements.

Tips

• Calculate total daily energy expenditure (TDEE) before setting macro targets — eating at the right calorie level matters more than the macro split for body composition goals.
• Protein targets are the most evidence-backed macro for muscle retention during a caloric deficit: 1.6-2.2g/kg of body weight per day.
• Track macros for 2-3 weeks before adjusting — initial water weight changes can mask true fat/muscle changes in the first week.

Fun Facts

• The macronutrient system (protein, carbohydrates, fat) was formalized by chemist Wilbur Atwater in the 1890s, who also measured caloric values of common foods — values still used in USDA nutritional databases today.
• The popular ketogenic diet targets <5% carbohydrates (<25g/day). By comparison, the 2020-2025 US Dietary Guidelines recommend 45-65% of calories from carbohydrates — a roughly 10x difference in the most restrictive keto vs. standard guidelines.
• Protein has a thermic effect of 20-30% — meaning 20-30% of calories from protein are burned during digestion. Carbohydrates have a 5-10% thermic effect; fat has only 0-3%.

FAQ

What's the difference between macros and calories?

Calories measure total energy. Macros are the three energy-containing nutrients: protein (4 cal/g), carbohydrates (4 cal/g), and fat (9 cal/g). Setting macros implicitly sets calories.

Does it use the Mifflin-St Jeor formula for TDEE?

Yes by default, as it's the most validated for non-obese adults. The Harris-Benedict (1919, revised 1984) and Katch-McArdle (uses lean mass) formulas are also available.

How do I adjust macros when I'm not losing weight?

Reduce daily calories by 100-200 kcal and maintain the same macro ratio. Adjust no more than every 2 weeks — allowing time for actual fat loss to be measurable against water weight fluctuation.