Macronutrients are the three nutrients that provide calories: protein and carbohydrate supply 4 calories per gram and fat 9 calories per gram (alcohol, at 7, is the other source). “Counting macros” means aiming for a number of grams of each instead of only a calorie total.

How much protein do I need a day?

The RDA for adults is 0.8 g per kg of body weight (about 0.36 g per lb), the amount that meets the needs of nearly all healthy adults. For people who exercise regularly, the International Society of Sports Nutrition suggests 1.4–2.0 g per kg (about 0.64–0.91 g per lb) to build and maintain muscle. Pick a level in the protein list to override the preset.

What is the best macro split for weight loss?

The calorie deficit drives weight loss; the split matters more for how full you feel, how you train and what you can stick to. Studies comparing low-carb and low-fat diets generally find similar weight loss when calories are matched. Enough protein helps you keep muscle while you lose fat.

Why does keto show a warning?

Keto deliberately takes carbs far below, and fat far above, the National Academies’ Acceptable Macronutrient Distribution Ranges (carbs 45–65%, fat 20–35% of calories). The flag is not a verdict on keto — it shows the plan is outside the ranges linked with adequate nutrients and lower chronic-disease risk. Talk to your doctor first if you take medicines for diabetes or blood pressure.

Why is my protein percentage so high?

Protein is set by body weight, not as a share of calories. On a low calorie target, or for heavier people, the same grams per kilogram become a bigger share. If protein goes above 35% of calories, choose a lower protein level; if you have a lot of weight to lose, try entering your goal weight in “I know my target” mode.

Do I have to hit my macros exactly?

No. Getting close most days, and averaging out over the week, works fine. Calorie and macro counts on labels and in apps are estimates too. Watch your weekly average weight and how you feel, and adjust.

Macro Calculator — Protein, Carbs & Fat for Your Goal

Turn a calorie target into daily grams of protein, carbs and fat — with protein set from your body weight, four approaches to choose from, and a check against the official healthy ranges.

How to use the macro calculator

Choose how to set your calories. Estimate for me works out your maintenance calories from sex, age, height, weight and activity (the same Mifflin-St Jeor method as our calorie calculator) and applies your goal, such as losing about 1 lb a week. I know my target takes a daily calorie number you already have — for example from the TDEE calculator or a dietitian — plus your weight. Then pick an approach. The daily grams of protein, carbs and fat appear instantly, with the calories and share of each and every step of the math. Until you type, the example shows a 35-year-old woman aiming to lose about 1 lb a week. Your inputs are kept in the page address so you can bookmark or share the result.

How the split is worked out

Protein (g)       = protein level (g per kg) × body weight (kg)
Fixed macro (g)   = share of calories × calories ÷ 4 (carbs) or 9 (fat)
The other one (g) = (calories − protein calories − fixed calories) ÷ 4 or 9
Energy: protein 4, carbohydrate 4, fat 9 calories per gram

Protein comes first and is set from body weight, because protein needs scale with the size of the body rather than with calories. Each approach then fixes either fat or carbs as a share of calories, and the remaining calories go to the other. Grams are rounded to whole numbers, so the total can differ from the target by a few calories; the working shows the exact check.

Approach presets
Approach	Protein	Fixed	The rest goes to
Balanced	1.4 g/kg (0.64 g/lb)	Fat 25% of calories	Carbs
Lower-carb	1.6 g/kg (0.73 g/lb)	Carbs 30% of calories	Fat
Higher-protein	2 g/kg (0.91 g/lb)	Fat 25% of calories	Carbs
Keto	1.4 g/kg (0.64 g/lb)	Carbs 5% of calories, at most 50 g	Fat

These presets are sensible starting points, not official prescriptions. Keto diets typically keep carbohydrate under about 50 g a day, which is why the keto preset caps carbs there.

How much protein?

The Recommended Dietary Allowance for adults is 0.8 g per kg of body weight a day (0.36 g per lb) — enough for nearly all healthy adults, but a minimum rather than a target for active people. The International Society of Sports Nutrition’s 2017 position stand concludes that 1.4–2.0 g per kg a day (0.64–0.91 g per lb) is sufficient for most people who exercise to build and maintain muscle, and that higher intakes may help resistance-trained people keep lean mass during a calorie deficit. The presets use 1.4 to 2.0 g per kg; the protein list lets you choose anything from the RDA to 2.2 g per kg (about 1 g per lb). If you carry a lot of excess weight, grams per kilogram of total weight can overshoot; entering a goal weight in “I know my target” mode gives a more realistic figure.

The AMDR check

The National Academies set Acceptable Macronutrient Distribution Ranges for adults: protein 10–35%, carbohydrate 45–65% and fat 20–35% of calories. They are the ranges linked with getting enough essential nutrients while keeping chronic-disease risk low, and the Dietary Guidelines for Americans use them too. Each macro card says whether it is inside its range. Lower-carb and keto plans leave the ranges on purpose, so they are flagged rather than blocked; a high protein share on a small calorie budget is flagged too.

Worked example

A 35-year-old woman, 5 ft 5 in and 160 lb (72.57 kg), lightly active, wants to lose about 1 lb a week. Her maintenance is 1,955 calories, so her target is 1,955 − 500 = 1,455 calories a day. With the balanced approach:

Protein: 1.4 g/kg × 72.57 kg = 101.6 → 102 g (408 calories, 28%).
Fat: 25% × 1,455 = 363.75 calories ÷ 9 = 40.4 → 40 g (360 calories).
Carbs: 1,455 − 408 − 360 = 687 calories ÷ 4 = 171.75 → 172 g (47.3%).

All three are inside the AMDR. Switching to keto at the same calories gives 102 g protein, 18 g carbs and 108 g fat — 66.8% of calories from fat, which the calculator flags as outside the 20–35% range.

Tips

Read labels in grams. US Nutrition Facts labels list protein, total carbohydrate and total fat per serving in grams, so they add up directly against your targets.
Quality still counts. Fiber-rich carbs, lean and plant proteins, and mostly unsaturated fats make any split healthier.
Adjust by results. If your weekly average weight is not moving as planned after two to three weeks, change calories first, not the split.
Related tools: the body fat calculator estimates lean mass, and the BMI calculator shows where your weight sits for your height.

Last reviewed 25 September 2026 · Built and checked by the Reeliy team · How we test our tools

Macro Calculator

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