Macro Calculator
| Macro | Grams | kcal | % |
|---|
How This Calculator Works
First, calorie target — Mifflin-St Jeor BMR × activity factor ± goal adjustment. Then, the diet-style preset splits those calories into protein, carbs, and fat percentages. Each gram is converted using its calorie density: protein and carbs at 4 kcal/g, fat at 9 kcal/g.
Calorie target = TDEE ± goal adjustment
Diet style splits (% of calories):
Balanced Protein 25 Carbs 50 Fat 25
High-protein Protein 35 Carbs 40 Fat 25
Low-carb Protein 30 Carbs 25 Fat 45
Keto Protein 25 Carbs 5 Fat 70
Grams = (calories × split%) / kcal-per-gram
protein: 4 kcal/g
carbs: 4 kcal/g
fat: 9 kcal/gCitations: BMR via Mifflin MD, St Jeor ST, et al., American Journal of Clinical Nutrition, 1990;51(2):241–247. Protein recommendations: Phillips SM, Van Loon LJ. "Dietary protein for athletes: from requirements to optimum adaptation." Journal of Sports Sciences, 2011;29(S1):S29–S38.
What This Means
Macro splits give you composition; calories give you the goal. Higher protein helps preserve muscle when you're losing weight and supports muscle gain when you're not. The carb-vs-fat ratio is mostly a personal preference — pick the diet style you can stick to without misery, since adherence is what actually drives results.
Limitations
The calorie target inherits Mifflin-St Jeor's ~10% accuracy, plus the 3,500 kcal-per-pound rule's tendency to overestimate long-term loss. Diet-style splits are starting points — individual responses vary, especially around carbs (some people feel great on high-carb, others on low-carb). Adjust if you've been consistent for 4 weeks and results are off.
Frequently Asked Questions
What are macros?
Macros — short for macronutrients — are the three nutrient groups that provide calories: protein, carbohydrates, and fat. Protein is 4 kcal/g, carbs 4 kcal/g, fat 9 kcal/g. 'Hitting your macros' means eating roughly the target grams of each per day, which is more useful for body composition than just hitting a calorie number.
How much protein should I eat?
For general health, 0.8 g per kg of body weight is the bare minimum (the RDA). For muscle building or fat loss, the research consensus (Phillips & Van Loon, 2011, and others) is 1.6–2.2 g per kg total body weight, or roughly 0.7–1.0 g per pound. This calculator uses 1.0 g per pound as the default for active adults.
Why is protein so high in this calculator?
Higher protein helps preserve muscle in a deficit, increases satiety, and has a higher thermic effect (your body burns more calories digesting protein than carbs or fat). Most modern dietitians recommend 1.6 g/kg or higher for adults trying to lose fat or gain muscle, well above the 0.8 g/kg RDA which assumes sedentary adults just trying to avoid deficiency.
What's the right diet style?
Whichever you can stick to. The research is pretty clear: as long as protein is adequate and total calories match your goal, the carb-to-fat ratio doesn't matter much for fat loss or muscle gain. Pick the one that fits your life. Like bread and rice? Balanced. Hate feeling carb-crashes? Low-carb. Endurance athlete? Higher carbs. Doctor told you to do keto for a specific reason? Keto.
What does 'keto' actually mean here?
In this calculator, keto means about 5% of calories from carbs (~20–30g/day for most people), which is enough to drive most adults into ketosis after a few days. That's a strict ratio. 'Low-carb' is more flexible at 25%. If you're new to keto, ramp down gradually rather than dropping carbs overnight.
Should I be precise to the gram?
No. Within 5–10g of each macro is fine for almost any goal. Tracking apps make precision tempting, but food labels themselves have ±20% legal tolerance, and your body doesn't do daily accounting — it averages over days. Hit your weekly average; don't stress about a single day.
How do I track macros?
Most people use a tracking app. The honest workflow: weigh and log accurately for 1–2 weeks to learn portion sizes, then maintain by repeating familiar meals (which you've already learned) and only logging new ones. Long-term spreadsheet-precision tracking burns most people out — knowing your typical breakfast and lunch in your head is sustainable.
Will higher protein help me lose more fat?
It can — by a few mechanisms. Protein has the highest thermic effect (you burn ~25% of protein calories digesting it, vs. 5–10% for carbs and fat). It also keeps you full longer and preserves muscle in a deficit, which keeps your metabolism higher. The Phillips & Van Loon (2011) review summarizes the muscle-preservation evidence well.