Macro Calculator

Protein is set per kilogram of body weight and fat as a share of calories, so carbohydrate takes what is left. The presets run 1.6 g of protein per kilogram for a balanced plan, 2.2 g/kg while cutting, 2.0 g/kg for a lean gain, and 1.8 g/kg with 70 percent of calories from fat on keto.

Sex

Age 30

1580

Height

Weight

Activity Level

Goal

Diet Style

Eating Window (for IF users)

Daily Calorie Target

kcal / day

Daily Macro Targets

Protein --

Carbohydrates --

Fat --

Total --

Macro Split

-- kcal

--%

Per-Meal Breakdown

Meal	Protein	Carbs	Fat	Calories

Fasting Insight

How this is calculated

Calories first, then the split, then the plates.

Maintenance comes from Mifflin-St Jeor — 10 × weight in kilograms + 6.25 × height in centimetres − 5 × age, + 5 for men or − 161 for women — multiplied by one of the conventional activity factors from 1.2 to 1.9. Your goal then moves that figure, and the result is clamped so intake never falls below 1,200 calories a day.

The preset splits set protein by body weight and fat by share of calories, and let carbohydrate take what is left: 1.6 g of protein per kilogram with 25 percent of calories from fat for a balanced plan, 2.2 g/kg and 25 percent for cutting, 2.0 g/kg and 35 percent for a lean gain, and 1.8 g/kg with 70 percent of calories from fat for keto. The 1.6 g/kg floor is the point at which added protein stopped producing further benefit for lean mass in the resistance-training meta-analysis; the higher figure while cutting is the same evidence read at its upper end, where a deficit makes protein matter more. Grams come out at 4 calories each for protein and carbohydrate and 9 for fat, which is where any one-or-two-calorie rounding difference in the totals comes from.

Meals are the eating window divided by three and capped at four, so an 8-hour window gives two meals and a 12-hour window gives four. Protein, carbohydrate and fat are then split evenly across them. That even split is a simplification the evidence does not entirely support — protein synthesis responds to distribution as well as to total — but it is the honest default when the tool does not know which of your meals sits next to a workout.

Where this comes from

1. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults — Morton et al., British Journal of Sports Medicine, 2018 (PubMed)
2. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis — Areta et al., The Journal of Physiology, 2013 (PubMed)
3. A new predictive equation for resting energy expenditure in healthy individuals — Mifflin et al., American Journal of Clinical Nutrition, 1990 (PubMed)

Nothing on this site is medically reviewed — it cites its sources so you can check them. Read our editorial policy. Method last checked 21 August 2026.

Macronutrient balance becomes especially important when you compress all your nutrition into a shorter eating window. Getting enough protein, healthy fats, and complex carbohydrates within your window ensures your body has everything it needs to recover, build muscle, and sustain energy through fasting hours.

Many intermittent fasters find that paying attention to macros — particularly protein — makes their fasts dramatically easier. A high-protein final meal before your window closes helps maintain satiety well into the fasting period.

Frequently Asked Questions

How do I calculate my macros for intermittent fasting?

Start by determining your daily calorie target from your TDEE and goal. Then split those calories into protein (typically 30-35%), fat (25-35%), and carbohydrates (the remainder). The key difference with IF is that you consume all these macros within your eating window.

Do macros matter when doing intermittent fasting?

Yes, macros still matter. While IF handles the timing of your meals, the quality and composition of what you eat during your window affects energy levels, muscle retention, and satiety. Prioritising protein and healthy fats helps you stay full through your fasting window.

What is the best macro split for fat loss?

A common starting point for fat loss is 30% protein, 35% fat, and 35% carbohydrates. Higher protein intake (up to 40%) helps preserve muscle mass during a deficit. The best split is one you can sustain consistently, so adjust based on your preferences.

How much protein do I need during intermittent fasting?

Aim for 0.7-1.0 grams of protein per pound of body weight daily, consumed within your eating window. This supports muscle maintenance and repair. Spreading protein across 2-3 meals during your window optimises muscle protein synthesis.

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Time your meals perfectly with the Fasted app eating window timer

The Fasted app reminds you when your eating window opens and closes, so you can plan your macro-balanced meals at the right times.

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