Macro Calculator

What are macros?

Macros, short for macronutrients, are the three nutrients your body needs in large amounts for energy: protein, carbohydrates (carbs), and fat. Vitamins and minerals are micronutrients, needed in milligrams rather than grams. This macro calculator, also called a macronutrient calculator or macro counter, turns your daily calorie needs into a target for each macronutrient in grams, which is easier to track on a food label or in a nutrition app.

How to calculate macros

The calculator works in three steps. First, it estimates your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, using weight in kilograms, height in centimeters, and age in years:

Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5
Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161

If you know your body fat percentage, you can use the Katch-McArdle formula instead: BMR = 370 + 21.6 × (1 − body fat % ÷ 100) × weight.

Second, BMR is multiplied by your activity factor (1.2 for sedentary up to 1.9 for extra active) and adjusted for your goal: minus 250, 500, or 1,000 Calories a day to lose about 0.5, 1, or 2 lb (0.25, 0.5, or 1 kg) a week, or plus the same amounts to gain.

Third, the daily calories are split between protein, carbs, and fat, then divided by the energy in each gram. This calculator uses 4.1 Calories per gram of protein, 3.75 per gram of carbs, and 8.8 per gram of fat.

grams of protein = calories × protein share ÷ 4.1

For example, a 32-year-old woman who is 5 ft 5 in and 140 lb with light activity needs about 1,851 Calories a day to maintain her weight. On the balanced plan that is 1,851 × 25% ÷ 4.1 ≈ 113 g of protein, 1,851 × 50% ÷ 3.75 ≈ 247 g of carbs, and 1,851 × 25% ÷ 8.8 ≈ 53 g of fat.

What the result includes

• Daily calories for your goal, also shown in kilojoules (1 Calorie = 4.1868 kJ).
• Grams of protein, carbs, and fat for the balanced, low fat, low carb, and high protein plans, or a custom plan you build with the sliders.
• A healthy range for each macro. Protein runs from the highest of 60 g, 10% of calories, and 1 g per kg of body weight (0.83 g per kg if you are sedentary) up to 35% of calories. Carbs run from 40% of calories up to whatever is left after the lowest protein and fat. The National Academies range for carbs is 45% to 65%; the lower bound here is 40% so that the low carb plan stays inside the range. Fat runs from 20% to 35% of calories. If a plan's protein share would fall under the minimum, that plan uses the minimum protein, the most carbs, and the least fat instead.
• Upper limits for added sugar and saturated fat, each at 10% of daily calories. Added sugar here means sugar added to food plus the sugar in honey, syrups, and fruit juice, not the natural sugar in whole fruit, vegetables, and milk.

If your calorie target is under 1,500 Calories a day for men or 1,200 for women, the calculator shows a note to talk to a doctor instead of a macro split.

Frequently asked questions

How do I use a macro calculator for weight loss?

Pick one of the weight loss goals. The calculator subtracts 250 to 1,000 Calories a day from your maintenance calories and splits the lower total into macros. Many people choose the high protein plan while losing weight, because protein helps keep you full and protects muscle. Recalculate every few weeks as your weight changes.

Can I use this as a macro calculator for muscle gain?

Yes. Choose a weight gain goal to add 250 to 1,000 Calories a day, then pick the balanced or high protein plan. A slow gain of about 0.5 lb (0.25 kg) a week keeps extra fat gain lower.

Does this work as a keto macro calculator?

Not exactly. A ketogenic diet usually keeps carbs under about 50 g a day, far below the 40% minimum used here. The low carb plan is the closest option, but follow a plan designed for keto if that is your goal.

Is this macro calculator free?

Yes. The macro calculator is free, needs no sign-up, and runs in your browser. Use the share button to save a link to your results.

How accurate are my macros?

They are a starting point. The BMR equations describe averages, so your real needs can be a few hundred Calories higher or lower. Track your weight for two to three weeks and adjust your calories if it is not moving the way you expect.

Limitations

The results are guidelines for healthy adults aged 18 to 80. They are not medical advice. Talk to a doctor or registered dietitian about your macronutrient needs if you are an athlete in heavy training, pregnant or breastfeeding, managing a health condition, or following a special diet.