Macro Calculator

Your daily protein, carbs and fat

Enter your measurements, pick an activity level and a goal, and choose a split. The tool works out your calorie target the same way the calorie calculator does, then divides it into grams of each macronutrient.

It also cross-checks your protein against your body weight — a comparison most macro calculators skip, and the one that catches the most common problem with percentage splits.

Everything runs in your browser. Nothing here is medical advice, and no split below is a recommendation.

The arithmetic, in full

There are only three constants:

Protein: 4 calories per gram. Carbohydrate: 4. Fat: 9.

Everything else follows. A 2,000 calorie day at 30% protein is 600 calories of protein, which is 150 g. The same 30% in fat would be 600 calories but only 67 g, because fat is more than twice as dense.

That density difference is why a “low fat” and a “low carb” diet at the same calories look so different on a plate, and why fat percentages sound smaller than they eat.

The splits

Balanced — 25% protein / 50% carbohydrate / 25% fat. The default, and the only one here with an official body behind it: it sits inside the Acceptable Macronutrient Distribution Ranges published by the Institute of Medicine (protein 10–35%, carbohydrate 45–65%, fat 20–35%). Start here unless you have a reason not to.

High protein — 40/30/30. For a deficit, or a training block where preserving muscle is the priority. Protein is also the most filling of the three, which makes a deficit easier to hold.

Low carb — 35/20/45. A preference, not a metabolic advantage. It suits people who find carbohydrate-heavy meals leave them hungry sooner.

Ketogenic — 25/5/70. Carbohydrate low enough to shift the body toward burning fat for fuel. It is a genuinely different metabolic state and it takes adjustment. Worth researching properly before starting, and worth discussing with a doctor if you take medication for diabetes.

Zone — 30/40/30. The 1990s split, still widely used as a middle ground.

Calories decide the direction; macros decide the ride

This is the thing worth internalizing before optimizing anything.

Whether you gain or lose weight is settled by the total. At the same calories, the split changes how the diet feels — how hungry you are, how your training goes, how much muscle survives a deficit — but not much about the number on the scale over a month.

Which means the ordering is: get calories roughly right first, get protein adequate second, and treat the carbohydrate/fat balance as a preference to be settled by what you can actually stick to. People who reverse that order spend a great deal of effort on the least consequential variable.

The protein problem with percentage splits

Here is the flaw this tool exists to catch.

A percentage split ties protein to how much you eat. But protein requirement tracks body mass and training, not appetite. The two come apart exactly where it matters most.

Take someone at 120 kg cutting hard on 1,600 calories. At 25% protein that is 100 g a day — about 0.8 g per kilogram, the bare RDA minimum, at the precise moment they are in a deficit and most at risk of losing muscle. The same 25% on a 3,500 calorie bulk hands them 219 g, comfortably more than anyone can use.

So the tool computes grams per kilogram alongside the split and flags it when the split lands low. The comparison table shows four reference points:

0.8 g/kg — the RDA. A minimum for avoiding deficiency, not a target.
1.4 g/kg — the bottom of the range for people who train.
1.8 g/kg — a reasonable target when building muscle.
2.2 g/kg — commonly used when cutting, to protect muscle.

The 1.4–2.0 range comes from the International Society of Sports Nutrition’s position stand. Above roughly 2.2 g/kg there is little evidence of further benefit for most people.

Do you have to hit the numbers?

No, and trying to hit them exactly is how people give up in week three.

Within 5–10 g on protein and roughly in the neighborhood on carbohydrate and fat is fine. What matters is the average across a week, not the accuracy of any single day. A day that lands at 40% fat instead of 25% changes nothing; a month of eating half your protein target does.

Weigh food for a week or two if you have never done it — most people’s estimates of portion size are badly wrong in a consistent direction, and calibrating once is worth more than tracking imprecisely forever.

What this does not cover

Macros are three numbers about energy. They say nothing about food quality, fiber, micronutrients, or how you feel.

You can hit any split here entirely on protein shakes, white bread and butter, and it would be a poor diet by every measure that is not on this page. Fiber in particular is invisible to macro tracking and matters a great deal — most people get well under the 25–30 g a day generally recommended.

Alcohol is the fourth energy source at 7 calories a gram, and appears in no split. It counts toward your total whether or not you track it.

If you are pregnant or breastfeeding, under 18, managing diabetes or kidney disease, or have a history of disordered eating, the numbers here are not the right starting point. Talk to a registered dietitian. Calorie and macro tracking is not appropriate for everyone, and for some people it is actively harmful.

Frequently asked questions

What are macros?

The three nutrients that supply energy: protein, carbohydrate and fat. Protein and carbohydrate give about 4 calories a gram, fat about 9 — those three numbers are physical constants, and they are the whole of the arithmetic. Tracking macros means hitting targets for each rather than only counting the total.

Which split should I use?

Balanced (25/50/25) unless something specific says otherwise — it sits inside the official Acceptable Macronutrient Distribution Ranges, which is more than the others can claim. High protein suits a deficit or a training block; low carb and keto are preferences that work for some people; none is inherently superior for weight loss at the same calories.

Does the split matter more than the calories?

No. Calories decide whether you gain or lose; the split mostly decides how comfortable it feels and how much muscle you keep. The one part with strong evidence behind it is protein — enough protein preserves muscle in a deficit and is the most filling of the three.

Why does the tool say my protein is low?

Because a percentage split scales protein with how much you eat rather than with your size. On a deep deficit, 25% of a small calorie target is a small amount of protein for a large body — which is exactly when protein matters most. The tool compares the split against grams per kilogram of body weight and flags the mismatch.

How much protein do I actually need?

The RDA is 0.8 g per kilogram of body weight, but that is a minimum for avoiding deficiency, not a target. For anyone training, the International Society of Sports Nutrition's position stand puts the useful range at 1.4–2.0 g/kg, and up to about 2.2 g/kg is commonly used when cutting to protect muscle.

Do I have to hit the numbers exactly?

No, and trying to is how people burn out. Within 5–10 g on protein and roughly in the neighborhood on the other two is fine. Consistency over weeks beats precision on any single day.

Is this medical advice?

No. No split here is a recommendation — they are the conventional starting points people arrive looking for. A real plan depends on your training, health and preferences. Talk to a registered dietitian before making a significant change, especially if you are pregnant, under 18, or managing a health condition.