Macro Calculator

What this calculator does

Calories tell you how much to eat. Macros tell you what those calories should come from.

Once you enter your calorie target, this calculator works out how many grams of protein, carbohydrate and fat to aim for each day. Results are shown in grams because that is how food labels and nutrition tracking apps measure macronutrients — and alongside them in calories, so you can see how the split divides your energy.

What are macros?

Macronutrients — usually shortened to macros — are the three nutrients that provide energy.

Protein

Protein provides 4 calories per gram. It helps build and repair muscle, maintain muscle during weight loss, support immune function, and increase fullness after meals.

Good sources include chicken, turkey, lean beef, fish, eggs, Greek yoghurt, cottage cheese, tofu, beans and lentils. If protein is the macro you find hardest to hit, our guide to hitting your protein goals every day and our list of high-protein snacks are the practical follow-ups.

Carbohydrates

Carbohydrates also provide 4 calories per gram. They are the body's preferred fuel, particularly for walking, running, cycling, HIIT, weight training and brain function.

Healthy sources include oats, potatoes, rice, pasta, fruit, vegetables, wholegrain bread and beans. Choosing mostly higher-fibre carbohydrates helps keep you fuller for longer on the same number of calories.

Fat

Fat provides 9 calories per gram, making it the most energy-dense macronutrient. That density is why fat targets look small in grams next to carbohydrate targets, even when both supply a similar share of your energy.

Despite being calorie-dense, fat is essential. It supports hormone production, absorption of the fat-soluble vitamins A, D, E and K, skin health, brain function and cell health. Good sources include olive oil, avocado, nuts, seeds, salmon and mackerel.

The longer version of all this is our complete guide to macros, and macro foods lists the best everyday sources of each.

How macro calculations work

Every calorie you eat comes from protein, carbohydrate or fat. The calculator divides your daily calories between those three, then converts each share into grams using its energy value.

For a 2,000 calorie target on a balanced split:

grams = (calories × percentage) ÷ calories per gram

Because each macro is rounded to whole grams, the three figures can add up to slightly more or less than your target. Where that gap is big enough to notice, the calculator says so rather than leaving you to find it.

Which macro split should you choose?

There is no single correct macro split. The best option depends on what you are training for, what you enjoy eating, and what you can stick to.

Balanced (30/40/30)

Suitable for most people, and close to UK Eatwell Guide proportions. A sensible default for healthy eating, weight maintenance, beginners and general fitness.

Weight loss (35/35/30)

Higher protein helps preserve muscle while in a calorie deficit and tends to improve fullness, which makes the deficit easier to hold. Pair it with the calorie deficit calculator to set the calorie figure first.

Muscle gain (30/45/25)

Protein requirements rise when you train with resistance regularly, and carbohydrate is kept high to fuel those sessions. Most guidance lands between 1.6 and 2.2g of protein per kilogram of body weight — enter your weight above and the calculator will tell you where your target sits in those terms.

High protein (40/30/30)

The highest protein share offered here. Useful if you consistently fall short on protein, or are eating in a deficit while training hard. See our high-protein meal plan for what this looks like as actual meals.

Low carb (35/25/40)

Reduces carbohydrate while keeping calories the same, with fat making up the difference. Often chosen by people reducing sugar intake, or managing blood glucose under appropriate guidance. Our keto vs low carb comparison explains where the two differ.

Keto

Ketogenic diets typically limit carbohydrate to around 20–50g per day, with most calories coming from fat. This calculator treats keto differently from the other options for that reason: rather than applying a fixed percentage, it fixes carbohydrate near 30g a day and gives fat the remainder. A percentage would be misleading here, because 5% of 1,400 calories and 5% of 3,000 calories are very different carbohydrate allowances.

Keto is more restrictive than the other patterns on this list, so it is worth understanding properly before starting. Our guide to tracking macros on a keto diet covers the practical side, and Mealiv supports keto meal planning directly.

Custom

Enter your own three percentages if you are following a plan from a coach or clinician. They need to total 100 — the calculator will ask you to correct them rather than quietly rescaling numbers you did not choose.

Do macros matter for weight loss?

Calories remain the biggest factor in losing weight. Macros do not override that — but they do change how easy your calorie target is to live with.

Eating enough protein can help preserve muscle while you lose fat, reduce hunger between meals, and support recovery from exercise. Eating enough carbohydrate supports training performance, and healthy fats remain important for hormones and overall health.

For most people, consistently hitting calories matters more than achieving perfect macro percentages every day. Treat the macro targets as a direction of travel, not a daily exam.

Should I count macros?

Macro tracking is not essential, but plenty of people find it useful. It tends to help if you want to increase your protein, struggle to eat enough of it, are building muscle, train regularly, enjoy measuring progress, or have specific nutrition goals to work towards.

Others simply prefer tracking calories and eating sensibly around that. Mealiv supports either approach — you can log against full macro targets, or just watch your calories and let the rest look after itself.

Track your macros automatically with Mealiv

Knowing your macro targets is only half the job. The harder part is knowing where you are against them at four o'clock on a Wednesday.

Mealiv tracks protein, carbohydrate, fat, fibre, sugar, saturated fat, vitamins and minerals as you log. You can log by typing, speaking, photographing a meal or scanning a barcode, and your nutrition dashboard updates immediately so you can see what is left in the day.

You can also build a week of meals that already fits your targets with the AI meal planner, or check any recipe against them using the recipe nutrition calculator.

Important information

These macro targets are estimates for informational purposes only and do not constitute medical or dietary advice. Consult a qualified healthcare professional before making significant changes to your diet, particularly if you are pregnant, managing a health condition, or considering a ketogenic diet.