A macro calculator breaks your daily calorie target into exact grams of protein, carbohydrates, and fat — the three macronutrients that power your body. Whether you are following a balanced diet, going low-carb, or trying keto, the right macro split makes it far easier to hit your goal, fuel workouts, and preserve muscle while losing fat.
Your Stats
Diet Preset
Percentages must add up to 100%.
Protein & carbs = 4 cal/g • Fat = 9 cal/g
Per-Meal Targets
How to Use the Macro Calculator
Getting your macronutrient targets right is one of the most effective ways to make progress toward any body composition goal. Too many calories and you gain unwanted fat; too few and you risk losing muscle. The right macro split on top of the right calorie target makes the difference between spinning your wheels and seeing consistent results. This free macro calculator does all the maths in seconds.
Step 1: Choose Your Units and Enter Your Stats
Use the metric/imperial toggle to pick the measurement system you prefer. Then enter your age, gender, height, and weight. These values go into the Mifflin-St Jeor equation — the most widely validated formula for estimating Basal Metabolic Rate (BMR). The BMR is multiplied by your activity level to produce your Total Daily Energy Expenditure (TDEE), which is the foundation for all macro targets.
Step 2: Select Your Activity Level
Be honest about your typical week. If you walk 30 minutes a day but otherwise sit at a desk, choose Lightly Active. If you train at the gym four or five times a week with moderate intensity, Moderately Active fits better. Overestimating activity is one of the most common reasons people fail to see expected results — when in doubt, choose the lower option and adjust later.
Step 3: Pick Your Goal
Select Lose Weight to subtract 500 calories from your TDEE, which creates a deficit that results in roughly 0.45 kg (1 lb) of fat loss per week. Select Maintain Weight to eat at your TDEE. Select Gain Weight to add 500 calories, which supports muscle growth at a controlled rate without excessive fat gain.
Step 4: Choose a Diet Preset
After calculating, select the diet style that matches your approach. Balanced (40/30/30 carbs/protein/fat) works well for most people. Low Carb (20/40/40) suits those who feel better with fewer carbohydrates. High Protein (30/40/30) prioritises muscle preservation and satiety. Keto (5/25/70) keeps carbs minimal for those in nutritional ketosis. Or switch to Custom and set your own percentages using the sliders — the pie chart updates live as you drag.
Step 5: Review Your Per-Meal Targets
Use the Per-Meal Targets section to divide your daily macronutrient budget by the number of meals you eat. Whether you prefer three traditional meals or five smaller ones, this section gives you a concrete gram target for each sitting, making it much easier to plan and track without obsessing over calorie apps all day.
Tips for Hitting Your Macros
Protein is typically the hardest macro to hit, so plan protein sources first (chicken, eggs, fish, Greek yogurt, legumes) and fill in carbs and fat around them. Recalculate your macro targets every 4-6 weeks or whenever your weight changes by more than 5 kg, since your calorie needs shift as your body composition changes. Remember that consistency over weeks beats perfection on any single day.
Frequently Asked Questions
Is this macro calculator free to use?
Yes, the Macro Calculator is completely free with no limits. You can calculate your macronutrient targets as many times as you want with different stats, goals, and diet presets. There is no signup required and everything runs locally in your browser.
Is my personal data safe and private?
Yes, all calculations run entirely in your browser using client-side JavaScript. Your age, weight, height, and other personal details are never sent to a server, never stored in a database, and never shared with anyone. Once you close the page, your data is gone.
What are macronutrients and why do they matter?
Macronutrients are the three main categories of nutrients your body uses for energy: protein, carbohydrates, and fat. Protein supports muscle repair and growth, carbohydrates are the body's primary energy source, and fat supports hormones and cell function. Tracking macros helps you hit your calorie goal while ensuring the right balance of nutrients for your specific goal.
How does the macro calculator work?
The calculator first estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, which factors in your age, gender, height, weight, and activity level. It then applies a calorie modifier based on your goal (+500 for gain, -500 for loss) and splits the resulting calories into protein, carbs, and fat grams according to your chosen diet preset.
What is the difference between the diet presets?
Balanced (40/30/30) is a general-purpose split suitable for most people. Low Carb (20/40/40) reduces carbohydrates and increases protein and fat. High Protein (30/40/30) prioritises protein for muscle building. Keto (5/25/70) is a very-low-carb, high-fat diet that pushes the body into ketosis. Custom lets you set your own percentages.
How many grams of protein do I need per day?
For most active people, a common recommendation is 1.6 to 2.2 grams of protein per kilogram of body weight per day to support muscle maintenance or growth. The High Protein preset in this calculator targets around 40% of calories from protein, which falls within this range for most typical calorie intakes.
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is the most accurate formula for estimating Basal Metabolic Rate (BMR). For men it is: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women it is the same but minus 161 at the end. The BMR is then multiplied by an activity factor to get your TDEE, which is the basis for all macro calculations.
Can I use this tool on a keto diet?
Yes. Select the Keto preset to set your carbohydrates to just 5% of calories, fat to 70%, and protein to 25%. This keeps net carbs very low, typically under 20-30 grams per day for most calorie targets, which is the standard threshold for achieving nutritional ketosis.