Macro Calculator
Protein, carbs and fat targets for any calorie goal.
Macros 101
Macronutrients ("macros") are the three energy-providing nutrient categories: protein (4 cal/g), carbohydrates (4 cal/g) and fat (9 cal/g). Alcohol is technically a fourth (7 cal/g) but isn't a nutrient your body actually needs. Your daily calorie target can be hit with infinite combinations — different splits suit different goals and personal preferences. See Wikipedia on nutrients for the biochemistry background.
Picking a Macro Split
| Diet Approach | Split (P/C/F) | Best For |
|---|---|---|
| Balanced | 30/40/30 | Default — works for most goals |
| Mediterranean | 20/50/30 | Long-term heart health; whole foods, olive oil |
| Low Carb | 30/30/40 | Blood sugar stability, fat loss without ketosis |
| Ketogenic | 25/5/70 | Therapeutic (epilepsy), some metabolic conditions |
| High Protein | 40/35/25 | Muscle gain or aggressive cuts |
| High Carb (athlete) | 20/55/25 | Endurance athletes (marathoners, cyclists) |
| Plant-based | 15/55/30 | Whole-food vegan/vegetarian |
Two diets, same calories, very different outcomes
Two 80 kg men cut to 2,000 cal/day for 12 weeks, training similarly:
| Variable | Person A (Low Protein) | Person B (High Protein) |
|---|---|---|
| Daily protein | 60 g (0.75 g/kg) | 160 g (2.0 g/kg) |
| Daily calories | 2,000 | 2,000 |
| Weight lost | −6 kg | −6 kg |
| Muscle lost | ~2.5 kg | ~0.5 kg |
| Fat lost | ~3.5 kg | ~5.5 kg |
| Post-diet BMR | Drops 8-12% | Drops 2-4% |
Same weight loss on the scale. Completely different body. Person B keeps muscle, metabolism, and a lean look. Person A loses mostly muscle and looks "skinny fat" at the end. This pattern is consistently shown in sports nutrition research.
The Protein Rule
Of the three macros, only protein has a robust evidence-based minimum. The latest meta-analyses (Morton et al. 2018) and International Society of Sports Nutrition position stand converge on:
- Sedentary adults: 0.8 g/kg/day (US RDA minimum to prevent deficiency)
- Active adults / muscle maintenance: 1.2-1.6 g/kg/day
- Resistance training, muscle building: 1.6-2.2 g/kg/day
- Fat-loss phase preserving muscle: 1.8-2.4 g/kg/day (elevated to compensate for lower calories)
- Older adults (sarcopenia prevention): 1.2-1.5 g/kg/day, evenly distributed
Carbs and fats are largely flexible within reason. Carbs power high-intensity exercise. Fat supports hormones and satiety. Both are required to some minimum (~0.5-0.8 g/kg fat to maintain hormones; carbs flexible from near-zero in keto to 6+ g/kg in endurance training).
Calculating Your Targets
Once you have your daily calorie target:
- Pick a macro split based on your goal
- Multiply total calories × each percentage to get calories per macro
- Divide protein cal by 4 = protein grams; carbs cal by 4 = carb grams; fat cal by 9 = fat grams
Example: 2,500 cal/day at 30/40/30 = 188 g protein, 250 g carbs, 83 g fat. The calculator above does this automatically.
Frequently Asked Questions
Do macros really matter or is it just calories?
Calories drive weight change; macros drive body composition. Same 500-calorie deficit with 1.8 g/kg protein vs 0.5 g/kg: the first preserves muscle, the second loses it.
Is too much protein dangerous?
Not for healthy adults with normal kidney function. Research consistently shows intakes up to 2.5 g/kg/day are safe long-term. Those with existing kidney disease should consult a doctor.
What's "good" protein source?
Complete proteins (containing all 9 essential amino acids): chicken, fish, eggs, dairy, meat, soy, quinoa. Most plant proteins are incomplete individually but combine well (rice + beans = complete).
Does meal frequency matter for protein?
For muscle synthesis, distributing protein across 3-5 meals with ~25-40 g each is slightly better than one large dose. But total daily intake matters more than timing.