Macro Calculator

How to use the macro calculator

1. Pick US units (pounds, feet and inches) or metric.
2. Choose your sex and enter your age (18 or older), weight and height.
3. Select the activity level that matches a typical week, counting both exercise and how much you move at work.
4. Choose a goal: lose weight (−20%), lose slowly (−10%), maintain, or gain (+10%).
5. Pick a macro split: balanced, high-protein, low-carb or keto.
6. Read your daily calories and grams of each macro, plus your TDEE (total daily energy expenditure) and BMR (basal metabolic rate).

How the numbers are calculated

1. BMR with Mifflin-St Jeor

The equation, published in 1990 by Mifflin, St Jeor and colleagues, estimates resting energy expenditure:

BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, or − 161 for women.

Pounds and inches are converted to kilograms and centimeters first.

2. TDEE and goal

BMR is multiplied by an activity factor: 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (active) or 1.9 (very active). That is your TDEE. The goal then adjusts it by −20%, −10%, 0% or +10%.

3. Calorie floor

If the target falls below 1,200 kcal for women or 1,500 kcal for men, the calculator raises it to that floor and the Calorie floor result tells you so. Going lower is something to do only under medical supervision.

4. Macro split

Grams come from 4 kcal per gram of protein or carbohydrate and 9 kcal per gram of fat. All results are rounded to whole numbers.

Examples

Woman, 35, 160 lb, 5 ft 5 in, lightly active, lose slowly, balanced

BMR 1,422 kcal, TDEE 1,955 kcal. A 10% deficit gives 1,759 kcal: 110 g protein, 220 g carbs, 49 g fat. The protein works out to about 1.52 g per kg of body weight.

Man, 28, 185 lb, 5 ft 11 in, moderately active, maintain, high-protein

BMR 1,831 kcal and 2,838 kcal to maintain: 284 g protein, 248 g carbs, 79 g fat. That is about 3.38 g of protein per kg, far more than most people need (see below).

Woman, 62, 130 lb, 5 ft 2 in, sedentary, lose weight, low-carb

BMR 1,103 kcal, TDEE 1,324 kcal. A 20% cut would land below 1,200 kcal, so the floor applies: 1,200 kcal, with 105 g protein, 75 g carbs and 53 g fat. The real deficit is about 9%.

Reading and adjusting your results

Equations estimate an average. Your actual needs can differ, so track your weight for two to four weeks and adjust calories by about 100 to 200 kcal if it isn’t moving as intended.

For context, the National Academies’ Acceptable Macronutrient Distribution Ranges for adults are 45–65% of calories from carbohydrate, 20–35% from fat and 10–35% from protein. The balanced split sits inside them; low-carb and keto deliberately do not. The Dietary Guidelines for Americans 2025–2030 suggest 1.2 to 1.6 g of protein per kg of body weight a day and keeping saturated fat under 10% of calories. Because the splits are percentages, a large calorie target with the high-protein split can exceed that range by a lot; if so, move some calories to carbs.

Who should not use this tool: people who are pregnant or breastfeeding, anyone under 18, anyone with an eating disorder or a history of one, and people with diabetes, kidney disease or other medical conditions. Talk to a registered dietitian or your doctor instead.