Build Muscle
Macro Calculator
Your macros are the grams of protein, carbohydrate, and fat that make up your daily calories. This calculator anchors protein to your body weight at 1.6 to 2.2 g/kg by goal, keeps fat at or above 0.6 g/kg, and fills the remaining calories with carbs.
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Learn how this works
How to Calculate Your Macros
The order that matters for setting macros: protein first from body weight, a fat floor next, and carbohydrate filling the remaining calories.
Read the guideKey facts about macros
- Protein and carbohydrate provide 4 calories per gram; fat provides 9 calories per gram.
- Protein targets of 1.6 to 2.2 grams per kilogram of body weight support muscle retention and growth for active people.
- Fat should not fall below 0.6 grams per kilogram of body weight per day, a floor that protects hormone production.
- For an 80 kg person on 2000 kcal cutting calories, this calculator sets 160 g protein, about 215 g carbs, and 56 g fat.
How does this macro calculator set your numbers?
Macros, short for macronutrients, are the three nutrients that provide energy: protein at 4 calories per gram, carbohydrate at 4, and fat at 9. Hitting the right split helps you keep muscle, train hard, and stay full while you change your weight. Rather than slicing your calories by fixed percentages, this calculator builds your macros in the order that actually matters. The underlying calorie estimate uses the Mifflin-St Jeor equation (1990), documented with every other formula on our methodology page.
Protein first, then fat, then carbs
Protein is set from your body weight, using 1.6 to 2.2 grams per kilogram depending on your goal, because protein needs scale with your size rather than with a flat percentage of calories. Fat is set from your preset but never allowed below 0.6 grams per kilogram, which protects hormone health on lower calorie plans. Whatever calories remain after protein and fat become your carbohydrate, the body's main training fuel. This order keeps the two essential macros adequate at any calorie level.
| Preset | Protein | Carbs | Fat |
|---|---|---|---|
| Lose Weight | 2.0 g/kg | ~35% | ~25% |
| Maintain | 1.6 g/kg | ~40% | ~30% |
| Build Muscle | 1.8 g/kg | ~45% | ~25% |
| Keto | 1.8 g/kg | ~5% | ~70% |
| Low Carb | 1.8 g/kg | ~20% | ~45% |
Worked example
An 80 kg person eating 2000 calories on a fat loss goal is set to 2.0 grams of protein per kilogram, which is 160 grams, or 640 calories. Fat at 25 percent of calories is 500 calories, which is about 56 grams, comfortably above the 0.6 g/kg floor of 48 grams. That leaves 860 calories for carbohydrate, roughly 215 grams. The result is 160 g protein, 215 g carbs, and 56 g fat.
Which preset should you use?
The Lose Weight preset leans on protein to protect muscle in a deficit. Maintain is balanced for holding steady. Build Muscle adds carbohydrate to fuel training in a surplus. Keto pushes fat high and carbs very low, and Low Carb sits between. If you are actively cutting and want the most muscle-sparing setup, the dedicated macro calculator for cutting uses an even higher protein target. To decide how many calories to eat in the first place, start with the TDEE calculator and, for fat loss, the calorie deficit calculator.
When are macro targets not the right tool?
If you are brand new to nutrition changes, tracking three numbers on day one can be overwhelming; getting total calories roughly right matters far more at the start. Macro precision also matters little if a medical condition governs your diet, where professional guidance comes first. And you do not need to hit these numbers perfectly: land within about 5 grams of your protein and fat targets, let carbohydrate absorb the rest, and judge yourself on the weekly average rather than a single day. If your goal is keto specifically, the keto calculator adds net carb counting and a carb limit.
Macro splits for women, bodybuilding, and low carb
The same free macro calculator works across goals because it builds your carb, protein, and fat ratio from your own body weight rather than a fixed template. For women the logic is identical, only the absolute grams are smaller, and the 1200 calorie floor still applies. For a bodybuilding split, keep protein toward 2.2 g/kg and let carbohydrate rise to fuel training volume. For a low carb macro split, choose the Low Carb or Keto preset, which raises fat and trims carbohydrate while holding protein steady. Whatever the target, protein and fat are locked in first as a macro split calculator should, so carbohydrate simply fills what remains.
Limitations of this calculator
Macro targets are a framework, not a prescription. The calorie figure underneath them is itself an estimate within about 10 percent, and food-label and portion errors add more variance than small percentage tweaks ever will. The tool assumes healthy adults and does not adjust for diabetes, kidney disease, pregnancy, or other conditions where a clinician should set your carbohydrate and protein. Protein needs are based on body weight or lean mass, not measured nitrogen balance. Use the numbers as a starting split, hold them for a few weeks, and adjust from real results.
Factors that change your macros
- Calorie target: everything is built inside your calories, so an accurate maintenance figure from the TDEE calculator matters most.
- Goal preset: losing, maintaining, gaining, keto, and low carb each set protein, fat, and carbohydrate differently.
- Body weight and composition: protein is anchored to weight or lean mass, so both move your grams.
- Activity: more training generally means more carbohydrate to fuel and recover from it.
- Food-label accuracy: real-world tracking error usually dwarfs small percentage tweaks, so weigh and log honestly.
- Individual response: appetite, digestion, and preference decide how well a split fits, so adjust from a few weeks of results.
Sources and references
- Institute of Medicine (National Academies). Dietary Reference Intakes: Acceptable Macronutrient Distribution Ranges. 2005. nationalacademies.org
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014. PubMed 24864135
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure. Am J Clin Nutr. 1990. PubMed 2305711
Split logic and constants are documented on the methodology page.
Frequently asked questions
How does this macro calculator set my numbers?
Protein is anchored to body weight first, at 1.6 to 2.2 grams per kilogram by goal, because protein needs scale with body size. Fat comes from your preset but never below 0.6 grams per kilogram, and carbohydrate fills the remaining calories.
What are the best macros for weight loss?
A higher protein split works well in a deficit, around 40 percent protein, 35 percent carbohydrate, 25 percent fat, because protein preserves muscle and keeps you full. Hitting protein and total calories matters more than exact percentages.
Do I need to hit my macros exactly?
Land within about 5 grams of protein and fat targets and let carbohydrate absorb the rest. Weekly consistency beats single day precision, and protein is the highest priority target.
How many calories should I use as the input?
Use the target for your goal: TDEE minus a deficit for fat loss, TDEE directly for maintenance, TDEE plus a modest surplus for muscle gain. Get your TDEE from the TDEE calculator, then split it here.
Why did my carbs come out low on the keto preset?
The keto preset sets carbohydrate to about 5 percent of calories and pushes fat high, which keeps most people in ketosis. For a dedicated view with net carbs, use the keto calculator.