Macro Calculator in kJ and Calories

Macro Calculator in kJ and Calories

This macro calculator turns a daily energy target into grams of protein, fat and carbohydrate. Enter your target in kilojoules or calories (or estimate one from your body details), then a percentage for each macro inside the Australian ranges: protein 15% to 25%, fat 20% to 35% and carbohydrate 45% to 65%, drawn from the Nutrient Reference Values.

The grams are arithmetic and any estimated target is approximate. Neither is a diet plan, and outcomes vary between individuals.

Last updated: November 2026

Work out your macros

Enter your daily energy target, then a percentage for each macro. The three percentages must add up to 100%. The calculator is for adults. It does not cover pregnancy or breastfeeding, so please talk to a GP or nurse practitioner about those times.

Units
Enter the daily figure you are working from, or estimate one from your body details below. Please do not subtract a deficit from that target.
kJ a day
No target yet? Estimate one from your body details

This optional step uses the same method as our calorie deficit calculator. It estimates the energy you would use at a healthy weight for your height and puts that figure in the target box. It is for adults aged 19 and over.

Sex
years
cm
kg
Heavy physical work or very active leisure already includes this, so the step does not add it to that choice.

15% to 25%
%
20% to 35%
%
45% to 65%
%

The example is 20% protein, 30% fat and 50% carbohydrate. You can change it, and it is not a recommendation.

The macro split is arithmetic only, and the target step gives an estimate. Outcomes vary between individuals. For advice about your own diet and goals, please speak with a GP, a nurse practitioner or an accredited practising dietitian.

How the Calculation Works

The calculator does the same three steps for each macro:

  • Share of energy. It multiplies your daily target by the percentage for that macro.
  • Energy per gram. It divides that share by the energy in one gram. In kilojoules, protein and carbohydrate have 17 kJ per gram and fat has 37 kJ (Better Health Channel). In calories, the figures are 4, 4 and 9 (FAO).
  • Rounding. It rounds grams to the nearest whole gram. The figure alongside uses 1 calorie = 4.184 kJ, the same factor as our kilojoules to calories converter, rounded to the nearest 10.

Here is one example in each unit, at 20% protein, 30% fat and 50% carbohydrate:

  • 9,000 kJ a day: 1,800 kJ / 17 = 106 g of protein, 2,700 kJ / 37 = 73 g of fat, and 4,500 kJ / 17 = 265 g of carbohydrate.
  • 2,000 calories a day: 400 / 4 = 100 g of protein, 600 / 9 = 67 g of fat, and 1,000 / 4 = 250 g of carbohydrate.

These targets and splits are examples only, not suggested intakes. The kJ and calorie modes can differ by a few grams for the same energy, because the per gram figures are rounded. For the full method, read how to calculate macros for weight loss.

Where Your Daily Target Comes From

If you do not have a target, open the optional body details step in the calculator. It follows the same steps as our calorie deficit calculator. It estimates the energy your body uses at rest from your sex, age and weight with the Schofield equations (FAO), then multiplies that figure by an activity factor for your usual day (Eat for Health). If your BMI is 25 or more, it runs the same sum at a BMI of 22 for your height, about the middle of the healthy range of 18.5 to 24.9. If your BMI is already in the healthy range, it uses the energy your body uses now. Nothing further is taken off, and the figure goes straight into the target box. The step does not set a target for a BMI under 18.5, and a GP or nurse practitioner can help with that.

The step gives an estimate only. People of the same age, sex and size who seem equally active can still need very different amounts of energy, and the equations probably over-estimate the energy older people use at rest (Eat for Health).

If you already have a target, enter it as it stands, with no deficit subtracted from it. The article on what a calorie deficit is and how to work out yours explains the difference between a target and the energy you use now, and the BMR calculator estimates the energy you use at rest and across a day. For figures by age, sex and activity, read how many calories a day to lose weight.

A good weight management service will advise against a daily intake below 5,000 kJ (1,200 calories), according to the Better Health Channel. The calculator does not split a target below that figure.

Why the Calculator Keeps to the Australian Ranges

The ranges draw on the Nutrient Reference Values for Australia and New Zealand, which set out the evidence for each macro. Those recommendations were developed for adults and are for otherwise healthy people, on the assumption that usual intake keeps body weight steady. The same source says they are not necessarily recommendations for the best weight loss diet or for managing an existing chronic condition. The calculator stays inside the ranges because they are the Australian reference it is built on, and a GP, nurse practitioner or accredited practising dietitian can look at a split outside them with you. The Australian Dietary Guidelines recommend 45 to 65% of energy from carbohydrate (Better Health Channel).

Weight responds to total energy. The same source adds that if you eat more kilojoules than you use, you put on weight, whether those kilojoules come from fat, carbohydrate or protein. The split shapes your diet inside that total, and no single split suits everyone. For more, read popular macro splits checked against the Australian ranges.

Using Your Numbers With Food and Activity

Grams are one part of a healthy diet. The Australian Dietary Guidelines recommend a wide variety of nutritious foods from the five food groups every day, and limiting foods and drinks with saturated fat, added salt, added sugars and alcohol. To compare protein foods, read high protein, low calorie foods compared. For everyday choices, see the best foods for weight loss, by food group and a 7-day weight loss meal plan with kilojoules. For the wider picture, read how to lose weight: a realistic guide.

Regular physical activity matters too. Australia's guidelines for adults suggest 30 minutes or more of moderate to vigorous physical activity on most days, plus muscle-strengthening activities on 2 or more days a week. For ideas, read how many steps a day to lose weight.

If you have diabetes, kidney disease or another ongoing health condition, talk to a GP, nurse practitioner or accredited practising dietitian before changing your macros. A registered health practitioner can also help if diet and physical activity changes have not been enough for your health goals. Whether any treatment beyond diet and exercise suits you is a decision made after an individual assessment, and outcomes vary between individuals. Read more about weight loss treatment at Burst Health.

Frequently Asked Questions

What are macros in a diet?

Macros, short for macronutrients, are protein, fat and carbohydrate. All three contribute to the energy in your diet, which is why a daily energy target can be split between them. Alcohol also supplies energy, but it is not one of the three macros and the body does not need it. This calculator covers the three macros only, so it says nothing about vitamins, minerals or fibre.

What is the 4 4 9 rule?

The rule gives the energy in one gram of each macro: 4 calories for protein, 4 for carbohydrate and 9 for fat. In kilojoules, the figures are 17, 17 and 37. To turn a share of energy into grams, divide by the matching figure. These are general factors, and more specific factors exist for some foods (FAO).

What should my macros be for 1,500 calories a day?

1,500 calories is about 6,280 kJ, and no single split suits everyone. To see the grams, choose Calories above, enter 1500 and add a percentage for each macro inside the ranges. The calculator cannot tell you whether 1,500 calories suits you, so please ask a GP, nurse practitioner or dietitian. This is arithmetic only, and outcomes vary between individuals.

How do I calculate my protein needs?

For adults aged 19 to 70, Australia's recommended dietary intake (RDI) is 0.75 g per kg of body weight for women and 0.84 g per kg for men (Nutrient Reference Values). Multiply your weight in kilograms by that figure. The published daily figures are 46 g and 64 g, and both rise after age 70. A GP, nurse practitioner or dietitian can advise you if this seems too high.

Why does the calculator not accept a 40/30/30 split?

The calculator only splits a target inside the Australian ranges. Written as 40% carbohydrate, 30% protein and 30% fat, this split has too little carbohydrate (the range starts at 45%) and too much protein (the range stops at 25%). The tool asks you to change those two figures. A GP, nurse practitioner or accredited practising dietitian can look at any other split with you.

Are macros different for women and men?

The calculator uses one set of percentage ranges for all adults, because the Australian ranges are not split by sex. The grams can still differ. Two people with different energy targets get different grams from the same split, and energy needs depend on age, sex, body size and activity. Protein intake figures are also published separately for women and men.

Can I use a macro calculator for muscle gain?

This calculator has no muscle gain setting. It only splits the target you enter inside ranges set for otherwise healthy adults. Muscle depends on more than a number of grams, as the best way to build it is by exercising and eating well (healthdirect). For a plan built around training, talk to an accredited practising dietitian.

References

This page is general information only and does not replace individual medical advice. Please speak with a registered Australian healthcare practitioner about your own circumstances.

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