Macro Calculator

A macro calculator turns a calorie target into grams of protein, carbohydrate and fat. A moderately active 35-year-old woman who weighs 65 kg and wants to lose fat needs about 1,540 kcal a day; on a balanced split that is roughly 104 g protein, 166 g carbs and 51 g fat.

By Editorial Team Updated 19 Oct 2026

How to use the macronutrient calculator

Enter your body details. Add sex, age, weight, height and activity so the calculator can estimate your calories, or type your own calorie target in the last box.
Pick a goal. Lose fat takes about 550 kcal a day off maintenance; build muscle adds about 275 kcal for slow, lean gains.
Choose an eating style. Protein is set from your body weight; the style decides how the remaining calories are split between carbs and fat.
Plan your meals. Use the per-meal row to build plates, then track for two weeks and adjust calories if your weight moves faster or slower than planned.

What macros are and how many calories each one has

Macronutrients are the three nutrients your body needs in large amounts:

Macronutrient	Calories per gram	Main job
Protein	4 kcal	Builds and repairs muscle and tissue; the most filling macro
Carbohydrate	4 kcal	Main fuel for the brain and high-intensity exercise
Fat	9 kcal	Hormones, absorbing vitamins A, D, E and K, and long-lasting energy

Alcohol supplies 7 kcal per gram but no nutrients, so it counts towards calories rather than any macro.

How this calculator sets your protein

Many calculators set protein as a fixed percentage of calories, which gives a heavy person far more protein than they can use and a small person on a diet too little. This one sets protein from body weight first, then splits the remaining calories between carbs and fat.

Adult reference intake for health: 0.8 g per kg a day.
For people who train regularly, the International Society of Sports Nutrition recommends 1.4–2.0 g per kg.
During a calorie deficit, intakes towards the top of that range help preserve muscle.

Protein is capped at 40% of calories, and for larger bodies it is based on the weight that gives a BMI of 27 for your height, so targets stay achievable.

Macros for weight loss: comparing eating styles

For the same 1,540 kcal fat-loss target (65 kg woman, moderately active):

Style	Protein	Carbs	Fat	Split (P/C/F)
Balanced	104 g	166 g	51 g	27/43/30%
High protein	130 g	159 g	43 g	34/41/25%
Low carb	117 g	114 g	68 g	30/30/40%
Lower fat	91 g	217 g	34 g	24/56/20%
Keto	98 g	19 g	119 g	25/5/70%

Studies that compare low-carb and low-fat diets at the same calorie intake find similar fat loss over a year. The best split is the one you can stick to, with enough protein to protect muscle.

Using it as a keto macro calculator

A ketogenic diet keeps carbohydrate very low, typically 20–50 g a day, so the body switches to burning fat and producing ketones. The keto setting fixes carbs at 5% of calories, sets protein at 1.5 g per kg, and fills the rest with fat. At 2,000 kcal that is about 98 g protein, 25 g carbs and 168 g fat.

Keto is not suitable for everyone. If you take insulin or other diabetes medication, blood pressure tablets, or are pregnant, talk to your doctor first because needs can change quickly when carbs are cut.

IIFYM calculator basics: hitting your numbers day to day

“If it fits your macros” (IIFYM) means any food can fit as long as the day’s totals land close to your targets. A few habits make that easier:

Get protein in at every meal: about 25–40 g per meal for most adults.
Aim for fibre: around 14 g per 1,000 kcal, from vegetables, fruit, pulses and whole grains.
Be within about 5–10 g of each target. Perfect numbers every day are not necessary; weekly averages matter more.
Weigh foods for the first couple of weeks. Portion guesses are usually low, especially for oils, nut butters and cereals.

Macro calculator FAQs

How much protein should I eat when dieting?

For general health 0.8 g per kg of body weight is the reference intake. If you lift weights or are losing fat, 1.4–2.0 g per kg is better supported. A 65 kg person would aim for about 91–130 g.

What is the best macro split for losing fat?

There is no single best split. Keep calories in a deficit, protein high enough to protect muscle (about 1.6–2.0 g per kg), and choose the carb and fat balance you can follow consistently.

Should I count net carbs or total carbs?

For keto, many people count net carbs (total carbs minus fibre). For other styles, total carbs are simpler. The figure shown here is total carbohydrate.

Do I need to hit my macros exactly?

No. Getting calories and protein right matters most. Being 5–10 g over or under on carbs or fat on any given day makes little difference.

How do I count macros in mixed meals?

Use the nutrition label or a food-tracking app, weigh the ingredients raw, and log the whole recipe once. Then divide by the number of portions.

Sources and methodology

Calories come from the Mifflin–St Jeor equation and standard activity factors, minus 550 kcal for fat loss or plus 275 kcal for muscle gain, rounded to 10 kcal (or your own target). Protein = style factor (1.4–2.0 g/kg) × body weight, using the weight at BMI 27 if lower, capped at 40% of calories. Fat is a fixed share of calories (20–40%); carbs fill the rest. Keto fixes carbs at 5% of calories and fat fills the rest. Protein and carbs use 4 kcal/g and fat 9 kcal/g. All example figures were produced by this calculator.

Macro Calculator

How to use the macronutrient calculator

What macros are and how many calories each one has

How this calculator sets your protein

Macros for weight loss: comparing eating styles

Using it as a keto macro calculator

IIFYM calculator basics: hitting your numbers day to day

Macro calculator FAQs

Sources and methodology

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