Macro Calculator
Turn a daily calorie target into grams of protein, carbohydrate and fat for a balanced, high-protein, low-carb, keto or custom split, or work out one macro on its own, checked against the official AMDR ranges.
How to Use
- Choose a mode: Macro split for all three macros, or Carbs, Fat or Protein to work out one macro on its own.
- Enter your daily calories in kcal or kJ. If you do not know them, work them out first with the TDEE Calculator.
- In Macro split, pick a split (balanced, high-protein, low-carb, keto, endurance) or Custom and type your own three percentages.
- In a single-macro mode, type the percentage of calories you want from that macro. In Protein mode you can add your weight to see grams per kg.
- Set how many meals you eat to get a per-meal figure, then check the chart: each macro is marked against its AMDR band.
Worked Example
A balanced 2,000 kcal day. With 20 % protein, 50 % carbohydrate and 30 % fat: protein = 2,000 × 0.20 ÷ 4 = 100 g, carbohydrate = 2,000 × 0.50 ÷ 4 = 250 g, fat = 2,000 × 0.30 ÷ 9 = 66.7 g. Check: 100 × 4 + 250 × 4 + 66.7 × 9 = 2,000 kcal. All three sit inside their AMDR ranges.
Carbohydrate on its own. At 2,000 kcal and 50 % from carbohydrate, carb calories are 1,000 and carb grams are 1,000 ÷ 4 = 250 g, about 83 g per meal over three meals. The fibre target at 14 g per 1,000 kcal is 28 g.
The common mistake: dividing fat calories by 4. 30 % of 2,000 kcal is 600 kcal from fat. Divided by 4, as for protein and carbohydrate, it looks like 150 g; but fat carries 9 kcal per gram, so the right answer is 600 ÷ 9 = 66.7 g, less than half as much.
Show Work
Formulas
Where 4, 4 and 9 Come From
The figures of 4 kcal per gram for protein and carbohydrate and 9 kcal per gram for fat are the general factors worked out by the American chemist Wilbur Olin Atwater, who burned foods in a bomb calorimeter and measured what the body excreted at the US Department of Agriculture in the 1890s. They are averages across foods, and they are still how energy is counted on food labels today.
The Acceptable Macronutrient Distribution Ranges were set by the Institute of Medicine of the US National Academies, with Health Canada, in the Dietary Reference Intakes report on energy and macronutrients (2002, published 2005). Rather than one ideal split, they give a range for each macronutrient that is linked to lower risk of chronic disease while still providing enough essential nutrients. The same report sets the adult protein RDA at 0.8 g per kg of body weight and bases the fibre recommendation on 14 g per 1,000 kcal; these figures appear in Health Canada’s published DRI tables.
About This Tool
This calculator splits a daily calorie target into grams of protein, carbohydrate and fat, and it also works out one macro at a time: Carbs mode gives grams, a per-meal amount and a fibre target, Fat mode gives grams and a saturated-fat limit, and Protein mode gives grams and, with your weight, grams per kilogram. Each result is drawn against the adult AMDR band so you can see at a glance whether a plan sits inside the ranges or deliberately outside them. Calories can be entered in kcal or kJ.
Everything runs in your browser; nothing you enter is sent anywhere. For general information only — not medical advice. Talk to a doctor or other qualified professional about your own health.
Related tools: TDEE Calculator, Protein Calculator, and BMI Calculator.
Frequently Asked Questions
How do you turn calories into grams of each macro?
Multiply your calories by the macro’s share, then divide by its energy per gram: 4 kcal for protein and carbohydrate, 9 kcal for fat. At 2,000 kcal and 50 % carbohydrate that is 2,000 × 0.5 ÷ 4 = 250 g of carbs.
What are the AMDR ranges?
The Acceptable Macronutrient Distribution Ranges set by the US and Canadian Dietary Reference Intakes for adults are 45–65 % of energy from carbohydrate, 20–35 % from fat and 10–35 % from protein. At 2,000 kcal that is 225–325 g of carbs, 44–78 g of fat and 50–175 g of protein.
Why does the keto split show as outside the ranges?
Because it is designed to be. At 2,000 kcal a 25 / 5 / 70 keto split gives 125 g protein, 25 g carbohydrate and 156 g fat: carbohydrate at 5 % is below its 45–65 % band and fat at 70 % is above its 20–35 % band. The calculator shows the numbers and marks where they fall.
How much fibre should I eat?
The fibre recommendation in the Dietary Reference Intakes is based on 14 g per 1,000 kcal, so a 2,000 kcal day calls for about 28 g and a 2,500 kcal day for 35 g. The Carbs mode shows this alongside your carbohydrate grams.
What is the limit for saturated fat?
The World Health Organization advises getting no more than 10 % of energy from saturated fat. Fat has 9 kcal per gram, so at 2,000 kcal the limit is 2,000 × 0.10 ÷ 9 = 22.2 g a day. The Fat mode shows this limit next to your total fat.
How do I use the Macro Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Does it cost anything or need an account?
No. The tool is completely free, there is no account to create, and it keeps working offline after the page first loads.
Is anything I type uploaded?
No. The tool works entirely on your device, so the values you enter never leave your browser.
Common Use Cases
A high-protein cut
1,800 kcal at 30 / 40 / 30 is 135 g protein, 180 g carbohydrate and 60 g fat, or 34 / 45 / 15 g over four meals.
Endurance fuelling
3,000 kcal at 20 / 60 / 20 puts 450 g of carbohydrate a day behind long training sessions.
Kilojoule labels
Enter 8,400 kJ and the calculator converts to 2,008 kcal before splitting it.
A carb budget
Carbs mode at 2,000 kcal and 50 % gives 250 g a day, 83 g per meal over three meals, with a 28 g fibre target.
Protein from a percentage
Protein mode at 2,200 kcal and 25 % gives 137.5 g, which is 1.83 g per kg for someone weighing 75 kg.
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