Macro Calculator: Protein, Carbs and Fat in Grams
Split a daily calorie target, typed or estimated from your details, into grams of protein, carbohydrate and fat with balanced, low-fat, low-carb, high-protein or custom percentages, beside the AMDR ranges in grams. Nothing is sent anywhere.
Enter a calorie target, or your details, to see your macros.
About the Macro Calculator
The Macro Calculator turns a daily calorie target into grams of the three macronutrients: protein, carbohydrate and fat. Type the calories you aim for, or let the calculator estimate them from your age, sex, height, weight, activity level and goal. Then choose a diet preset, or set your own percentages, and read how many grams of each macro to eat a day. A table puts your split beside the Acceptable Macronutrient Distribution Ranges (AMDR) from the US Dietary Reference Intakes, in percent and in grams.
Nothing is uploaded; every figure is worked out in your browser and the numbers you type never leave your device.
This is an estimate, not medical advice. Needs change with health, age, pregnancy and training, so ask a doctor or registered dietitian before a large change in your diet, especially if you have kidney disease, diabetes or another long-term condition.
How to use it
Steps
- Choose Enter calories and type a daily target, or choose Estimate from my details and fill in your profile, activity level and goal.
- Pick a diet: balanced, low fat, low carb, high protein, or custom percentages that add up to 100.
- Read the grams of protein, carbohydrate and fat, and compare your split with the AMDR table.
Estimated targets
The estimate uses the Mifflin-St Jeor equation for basal metabolic rate, multiplies it by your activity factor (1.2 to 1.9) and adds or subtracts 275, 550 or 1,100 kcal a day for a weekly change of 0.25, 0.5 or 1 kg, based on about 7,700 kcal per kilogram of body weight.
From calories to grams
Each gram of protein and carbohydrate provides about 4 kcal and each gram of fat about 9 kcal. These are the Atwater general factors used on food labels. For each macro:
The presets
Splits
- Balanced: 20% protein, 50% carbohydrate, 30% fat, inside every AMDR.
- Low fat: 20% protein, 60% carbohydrate, 20% fat, at the bottom of the fat range.
- Low carb: 30% protein, 25% carbohydrate, 45% fat, below the carbohydrate range and above the fat range.
- High protein: 35% protein, 40% carbohydrate, 25% fat, at the top of the protein range.
The presets are starting points, not prescriptions. The AMDR for adults are 10 to 35 percent of energy from protein, 45 to 65 percent from carbohydrate and 20 to 35 percent from fat.
Worked example
At 2,000 kcal a day with the balanced split, protein is 2,000 × 20% ÷ 4 = 100 g, carbohydrate 2,000 × 50% ÷ 4 = 250 g and fat 2,000 × 30% ÷ 9 ≈ 67 g.
Related tools
The Protein Calculator adds protein by body weight, the Carbohydrate Calculator and Fat Intake Calculator focus on one macro each, and the Calorie Calculator explains the energy estimate in more depth. The BMI Calculator shows where your weight sits.
Sources
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, 2005.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025.
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 1990;51(2):241–247.
Open-source credits
The calculations are implemented in-house in TypeScript, with no third-party libraries. They follow the Atwater general factors (4, 4 and 9 kcal per gram), the AMDR of the Institute of Medicine Dietary Reference Intakes and the Mifflin-St Jeor equation.
Frequently asked questions
How are calories turned into grams of each macro?
Protein and carbohydrate each provide about 4 kcal per gram and fat about 9 kcal per gram, the Atwater general factors used on food labels. The calculator multiplies your calorie target by each macro's share and divides by its factor. At 2,000 kcal and 30 percent fat, that is 600 kcal of fat, or about 67 g.
What are the Acceptable Macronutrient Distribution Ranges?
The AMDR are the ranges the US Dietary Reference Intakes link with a lower risk of chronic disease while still meeting nutrient needs. For adults they are 10 to 35 percent of calories from protein, 45 to 65 percent from carbohydrate and 20 to 35 percent from fat. The balanced preset, 20, 50 and 30 percent, sits inside all three.
How much protein do I need?
The RDA for healthy adults is 0.8 g per kilogram of body weight a day, or 56 g for someone weighing 70 kg. The 2016 ACSM joint position statement recommends 1.2 to 2.0 g per kilogram for people who train regularly. Open the protein view and enter your weight to see both figures.
Why must custom percentages add up to 100?
The three percentages divide the whole calorie target between protein, carbohydrate and fat, so together they must cover all of it. If they add up to more or less than 100, the grams would not match your calories, so the calculator asks you to adjust them first.
How much saturated fat is too much?
The Dietary Guidelines for Americans 2020–2025 recommend keeping saturated fat below 10 percent of calories, which is about 22 g at 2,000 kcal. The fat view shows this limit for your calorie target beside the 20 to 35 percent range for total fat.
Is my data stored or sent anywhere?
No. Everything is worked out in your browser, nothing is sent to a server, and the numbers you type are gone when you close the page.