How to use the macro calculator
- Choose how to set your daily calories: work them out from your details, or enter a number you already know.
- If you're working them out, enter your units, sex, age, height, weight, activity level and goal.
- Pick a macro split, or choose custom and enter your own percentages (they must add up to 100%).
- Choose how many meals you eat a day to see grams per meal.
How macros are calculated
When you work out calories here, the calculator uses the Mifflin-St Jeor equation for basal metabolic rate and multiplies it by your activity factor. It then adds or subtracts 250 or 500 kcal for your goal. A weight-loss goal never takes you below 1,200 kcal a day for women or 1,500 for men. Each macro's share of those calories is then turned into grams:
Protein and carbohydrate each provide about 4 kcal per gram and fat about 9, which is why the same share of calories gives far fewer grams of fat. Alcohol (7 kcal per gram) isn't counted.
| Preset | Protein | Carbs | Fat |
|---|---|---|---|
| Balanced | 20% | 50% | 30% |
| Low fat | 20% | 60% | 20% |
| Low carb | 30% | 25% | 45% |
| High protein | 35% | 40% | 25% |
Worked example
These are the calculator's defaults: a 35-year-old man, 175 cm, 70 kg, moderately active, maintaining weight, balanced split, 3 meals.
- Calories: BMR 1,623.75 × 1.55 = 2,516.8, so 2,517 kcal a day
- Protein: 2,517 × 20% = 503.4 kcal ÷ 4 = 126 g (1.8 g per kg of body weight)
- Carbs: 2,517 × 50% = 1,258.5 kcal ÷ 4 = 315 g
- Fat: 2,517 × 30% = 755.1 kcal ÷ 9 = 84 g
- Per meal: about 42 g protein, 105 g carbs and 28 g fat
With the low-carb preset, the same 2,517 kcal becomes 189 g protein, 157 g carbs and 126 g fat.
Choosing a split
The National Academies' Acceptable Macronutrient Distribution Ranges (AMDR) for adults are 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat. The balanced, low-fat and high-protein presets stay inside them. The low-carb preset goes below the carb range and above the fat range. Many people follow lower-carb diets, and the 2025–2030 Dietary Guidelines note that some people with chronic disease may do better on one with their health professional's help. Whatever split you choose, the guidelines' advice still applies: keep saturated fat to no more than 10% of calories, and favor whole foods over highly processed ones.
The best split is one you can keep up. Hitting roughly the same protein every day matters more than precise carb and fat numbers. If you have diabetes, kidney disease, high cholesterol or another condition, or you're pregnant, talk to a doctor or registered dietitian before changing your macros. For a closer look at one nutrient, try the protein calculator, the carbohydrate calculator or the fat intake calculator.
Frequently asked questions
What are macros?
Macronutrients are the three nutrients that supply calories: protein, carbohydrate and fat. "Counting macros" means tracking grams of each, rather than only total calories. Food labels list all three per serving.
What is the best macro ratio for weight loss?
Calories matter most for weight loss, and studies comparing diets with different macro splits at the same calories find similar results over a year. A higher protein share can help you feel full and keep muscle while losing weight. Choose a split that fits how you like to eat.
Do the percentages have to add up to exactly 100%?
Yes, because together they describe all of your calories. The calculator accepts a rounding difference of up to 0.5%. If your custom numbers don't add up, it asks you to adjust them.
How accurate do I need to be when counting macros?
Within about 5 to 10 grams a day is plenty for most people. Food labels themselves can be off by up to 20%. Consistency over weeks matters more than precision on any single day.
Related calculators
- Calorie Calculator — Daily calories to maintain your weight, plus gradual targets for losing or gaining, using the Mifflin-St Jeor equation.
- Protein Calculator — Daily protein in grams from your body weight, from the RDA minimum to targets for older adults and people who train.
- Carbohydrate Calculator — How many grams of carbohydrate a day fit 45–65% of your calories, with low, middle and high levels and grams per meal.
- Fat Intake Calculator — How many grams of fat a day fit 20–35% of your calories, and your saturated fat limit of 10%.
Results are estimates for general information and are not medical advice. Talk to a doctor or other qualified professional about your health. See our disclaimer.