Macro Calculator
Split your daily calories into protein, carb and fat grams with balanced, low-carb, high-protein or keto presets, or set protein in g/kg of body weight.
The interactive tool loads here when JavaScript runs.
About this toolWhat is the Macro Calculator?
The Macro Calculator turns a daily calorie number into grams of protein, carbohydrate and fat. You can estimate the calories here from age, sex, height, weight, activity and goal with the Mifflin-St Jeor equation, or type a target you already have from a dietitian, an app or the Calorie Calculator. Then choose how to divide them: balanced, low carb, high protein, keto, your own percentages, or protein fixed by body weight with carbs filling the rest.
Results show grams, calories and percentage for each macronutrient, grams per meal, protein per kilogram, and a fibre target. If a split falls outside the Acceptable Macronutrient Distribution Ranges published by the US Institute of Medicine, a short note says which one and by how much, so you can decide whether that is intentional.
The page does its maths in your browser, as you type.
- Mifflin-St Jeor estimate or your own calorie target
- Balanced, low carb, high protein, keto and custom presets
- Protein in g/kg with carbs filling the remainder
- Grams, calories and percent, plus grams per meal
- IOM range checks and a fibre target
How to use the Macro Calculator
- Choose Estimate for me and fill in sex, age, weight, height, activity level and goal, or choose I know my target and type your daily calories.
- Pick how protein is set: by percentage preset, or by grams per kg of body weight with a fat share.
- Select Balanced, Low carb, High protein, Keto or Custom. Custom percentages must add up to 100.
- Set meals per day to see grams per meal.
- Read the grams, check the range notes, and copy a summary for your food tracking app.
Worked examples
Moderately active man, maintenance, balanced
Input
Male, 30, 75 kg, 178 cm, moderate activity, maintain, Balanced 25/45/30
Output
2,662 kcal: protein 166 g, carbs 299 g, fat 89 g
BMR 1,717.5 × 1.55 = 2,662 kcal. Protein works out to 2.2 g/kg, at the top of the useful range for training.
Protein by body weight
Input
Known target 2,000 kcal, 70 kg, 1.8 g/kg protein, 30% fat
Output
Protein 126 g, fat 67 g, carbs 224 g
Protein takes 504 kcal and fat 600 kcal, leaving 896 kcal (224 g) for carbs, 45% of calories.
Keto at 1,800 kcal
Input
Known target 1,800 kcal, Keto 20/5/75
Output
Protein 90 g, carbs 23 g, fat 150 g
Carbohydrate is well under the 130 g RDA, which the page notes. That is intended for keto but worth knowing.
Background and insight
Protein and carbohydrate supply about 4 kcal per gram and fat about 9 kcal per gram, the Atwater factors still used on food labels. Grams therefore equal the calories assigned to a macronutrient divided by 4 or 9. At 2,000 kcal with 30% protein, 600 kcal ÷ 4 = 150 g. Alcohol supplies 7 kcal per gram and is not part of the split.
The Institute of Medicine's 2005 Dietary Reference Intakes set adult ranges of 10 to 35% of energy from protein, 45 to 65% from carbohydrate and 20 to 35% from fat, and an RDA of 0.8 g of protein per kg and 130 g of carbohydrate per day. Sports nutrition bodies go further on protein: the International Society of Sports Nutrition recommends 1.4 to 2.0 g/kg for people who train, and more during a calorie deficit to protect muscle. That is why the g/kg mode exists; for a 70 kg lifter, 1.8 g/kg is 126 g whatever the calorie target.
Low-carb and keto presets fall outside the carbohydrate range by design. Keto diets usually keep carbs under about 50 g a day so the body produces ketones; the 5% preset gives 22 g at 1,800 kcal. There is no single best split for weight loss: trials comparing low-fat and low-carb diets at equal calories find similar loss on average, so the split you can keep to is the right one.
Common use cases
Setting up a tracking app
Get exact gram targets to type into MyFitnessPal, Cronometer or MacroFactor.
Cutting while keeping muscle
Fix protein at 1.8 to 2.2 g/kg and let carbs and fat absorb the deficit.
Trying low carb or keto
See what the split means in grams before deciding whether it suits how you eat.
Meal prep
Divide daily grams by meals to plan portions.
Tips and limitations
- Get protein right first, then fat (at least about 20% of calories for hormone and vitamin absorption), and let carbs vary with training.
- Weigh yourself several times a week and compare two-week averages. If weight is not moving as planned, adjust calories by 100 to 200, not the split.
- Macros do not count fibre, vitamins or food quality. Aim for the fibre target shown, mostly from vegetables, fruit, legumes and whole grains.
- People with kidney disease, diabetes on medication, or who are pregnant should agree protein and carb targets with a clinician.
- For detail on calories use the Calorie Calculator; for protein evidence use the Protein Calculator. This page focuses on the split.
Frequently asked questions
How do I calculate my macros?
Decide on daily calories, choose percentages for protein, carbs and fat that add to 100, multiply calories by each percentage, then divide by 4 for protein and carbs and by 9 for fat. At 2,000 kcal and 30/40/30 that is 150 g protein, 200 g carbs and 67 g fat.
What is the best macro ratio for weight loss?
The ratio matters less than the calorie deficit and how well you can stick to it. Higher protein, around 1.6 to 2.2 g per kg, helps preserve muscle and keeps hunger down. Beyond that, choose the carb and fat balance you find easiest to follow.
How many grams of protein should I eat a day?
The RDA is 0.8 g per kg for sedentary adults. People who train regularly benefit from 1.4 to 2.0 g/kg, and up to about 2.2 g/kg while dieting. The Protein Calculator covers this in more depth.
What are keto macros?
Typically about 70 to 80% of calories from fat, 15 to 25% from protein and 5 to 10% from carbs, keeping carbs below roughly 20 to 50 g a day. The Keto preset here uses 75/20/5.
Do I count net carbs or total carbs?
The calculator gives total carbohydrate grams. Many keto followers track net carbs, which subtract fibre, because fibre adds little energy. If you track net carbs, keep fibre high and stay within the total shown.
Why does the macro calculator warn me about my split?
It compares each percentage with the US Institute of Medicine adult ranges: 10 to 35% protein, 45 to 65% carbs, 20 to 35% fat. Low-carb and high-protein diets intentionally go outside them. The note is information, not a judgement.
Is there an in-depth guide to the Macro Calculator?
Yes. “Body Fat, Ideal Weight and Macros: What the Formulas Can and Cannot Tell You” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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