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Macro Calculator

Get your daily calories and a protein, carbohydrate and fat target tailored to your goal — cut, maintain or bulk. Evidence-based and private; every calculation runs on your device.

MB By Mustafa Bilgic · Updated 2026-06-13 · 6 min read · Fitness Tools

Counting calories tells you how much to eat; counting macros tells you what those calories should be made of. This calculator estimates your daily calorie target for your goal — cut, maintain or bulk — then splits it into protein, carbohydrate and fat using evidence-based starting points. Protein is set from your bodyweight, fat as a share of calories, and carbs fill the rest. Everything runs on your device; nothing is uploaded.

Calculate your macros

cm
kg
–
calories / day for your goal
–
Protein
–
Fat
–
Carbs
Protein –Fat –Carbs –
Share of total calories from each macro.

What macros are — and why they matter

The three macronutrients are protein, carbohydrate and fat. Protein and carbs supply about 4 calories per gram; fat about 9. Two diets can have identical calories but very different effects on your body depending on the split — particularly how much protein you eat. Hitting a sensible protein target while managing carbs and fat is what lets you lose fat without losing muscle, or gain muscle without excess fat.

How this calculator works

  1. It estimates your maintenance calories with the validated Mifflin-St Jeor equation and your activity multiplier.
  2. It applies your goal: a ~500 kcal deficit to cut, a ~300 kcal surplus to bulk, or maintenance.
  3. It sets protein from your bodyweight (~1.8–2.2 g/kg), fat as a share of calories, and fills the rest with carbs.

The “approach” selector lets you shift toward lower-carb or higher-carb splits while keeping protein and calories on target. For the reasoning behind the protein figure, see how much protein to build muscle.

Example macro split (balanced)Protein20%Fat25%Carbs55%
An example balanced macro split by share of calories. Your personal split appears in the calculator above based on your goal.
Protein is the priority

If you only nail one macro, make it protein — it preserves muscle in a deficit, supports growth in a surplus, and keeps you full. Let carbs and fat flex around training and preference; what matters is hitting your calories and protein over the week.

Putting your macros to work

Use these numbers as a starting point and adjust based on real results over 2–3 weeks: if fat loss stalls, trim calories slightly; if you are gaining too fast, ease the surplus. Pair this with the TDEE calculator to understand your maintenance level, the protein calculator for a focused protein number, and the practical advice in bulking vs cutting.

Sources & further reading

  1. ISSN — Position Stand: Diets & Body Composition
  2. PubMed — Mifflin-St Jeor resting energy equation
  3. ACSM — Nutrition & Macronutrient Guidance

External links are provided for reference and do not imply endorsement. arsenal.fit is an independent publisher and is not affiliated with any cited organisation.

Not medical advice. arsenal.fit publishes general educational fitness information. It is not a substitute for professional medical guidance. Talk to a doctor before starting a new exercise programme, especially if you are pregnant, recovering from injury or illness, or managing a health condition. Sources are cited from public health and exercise-science organisations (CDC, ACE, NSCA, ACSM, PubMed).

Frequently asked questions

What are macros?
“Macros” are the three macronutrients that supply calories: protein, carbohydrate and fat. Protein and carbs provide about 4 calories per gram, fat about 9. Tracking macros — not just total calories — lets you control body composition: enough protein to build or keep muscle, with carbs and fat filling the rest of your energy needs.
How does this macro calculator work?
It estimates your maintenance calories using the well-validated Mifflin-St Jeor equation and your activity level, then adjusts for your goal (a deficit to cut, a surplus to bulk, or maintenance). It sets protein from your bodyweight, fat as a percentage of calories, and fills the remainder with carbohydrate — an evidence-based starting split you can adjust.
How much protein should my macros include?
This calculator targets roughly 1.8–2.2 g of protein per kilogram of bodyweight depending on your goal, with the higher end when cutting to protect muscle. That aligns with research on protein for body composition. You can read more in our how-much-protein guide; the calculator does the maths for you.
Should I eat the same macros every day?
Consistency helps, but you do not need to hit the numbers perfectly. Aim to land close to your protein target daily (it matters most), and let carbs and fat flex around training and preference. Many people eat more carbs on training days and slightly fewer on rest days — that is fine as long as weekly totals stay on track.
What's the best macro split for fat loss?
There is no single magic ratio — fat loss is driven by a calorie deficit. That said, keeping protein high (to preserve muscle and curb hunger) while moderating carbs and fat works well for most people, which is what the “cutting” setting here does. Choose carb and fat levels you can sustain; adherence beats any specific ratio.
Do I need to track macros to see results?
No, but it helps, especially early on. Tracking teaches you what your targets actually look like in food, which builds lasting habits. Once you understand portions, many people transition to looser tracking or simple rules. The calculator gives you the numbers; how strictly you follow them is up to you.

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