Macro Calculator
Find your daily calorie target and your protein, carb, and fat grams in seconds.
Enter your age in years (10 to 100).
Pick a preset or type your own percentages. The three values must add up to 100.
A macro calculator estimates your daily calorie needs with the Mifflin-St Jeor equation, then converts your chosen macro split into grams of protein, carbs, and fat. Protein and carbs provide 4 calories per gram while fat provides 9. Knowing your gram targets makes hitting a calorie goal far more precise than counting calories alone.
Whether you want to lose fat, build muscle, or simply eat with more intention, your total calories only tell half the story. The other half is the mix: how much protein protects your muscle, how many carbs fuel your training, and how much fat supports your hormones. This macro calculator works out both halves in seconds, and you can explore all of our nutrition tools on the fitness and health calculator hub page.
How the Macro Calculator Works
The calculator runs four quick calculations behind the scenes. Each one is based on well studied nutrition science, not guesswork.
Step 1: Your BMR (Basal Metabolic Rate)
BMR is the number of calories your body burns at complete rest just to stay alive: breathing, circulation, and cell repair. We use the Mifflin-St Jeor equation, which researchers consider the most accurate widely available formula:
- Male: (10 x weight in kg) + (6.25 x height in cm) – (5 x age) + 5
- Female: (10 x weight in kg) + (6.25 x height in cm) – (5 x age) – 161
For example, a 35 year old man who weighs 80 kg and stands 180 cm tall gets (10 x 80) + (6.25 x 180) – (5 x 35) + 5 = 800 + 1,125 – 175 + 5 = 1,755 calories at rest.
Step 2: Your TDEE (Total Daily Energy Expenditure)
BMR covers rest, but you also burn calories through movement. Multiplying BMR by an activity factor gives your TDEE, the calories you burn on a typical day:
| Activity level | Multiplier | What it means |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise |
| Lightly active | 1.375 | Light exercise 1 to 3 days per week |
| Moderately active | 1.55 | Moderate exercise 3 to 5 days per week |
| Very active | 1.725 | Hard exercise 6 to 7 days/week |
| Extra active | 1.9 | Physical job plus hard training |
Our 35 year old example at a moderate activity level burns 1,755 x 1.55 = 2,720 calories per day. That is his TDEE.
Step 3: Your Goal Adjustment
Eating exactly your TDEE keeps your weight steady. To change weight, you adjust from there:
| Goal | Adjustment | Example (TDEE 2,720) |
|---|---|---|
| Lose weight | -500 calories | 2,220 per day |
| Maintain | +0 calories | 2,720 per day |
| Gain weight | +300 calories | 3,020 per day |
A 500 calorie deficit produces roughly one pound of fat loss per week for most people. For safety, the calculator never sets a loss target below 1,200 calories and shows a warning when the floor applies. If weight loss is your goal, our calorie deficit calculator can help you fine tune the size of your deficit.
Step 4: Percentages Become Grams
Finally, your calorie target is divided by your macro split using the Atwater factors: 4 calories per gram for protein, 4 for carbs, and 9 for fat. A 2,720 calorie target on the Balanced split (30% protein, 40% carbs, 30% fat) becomes 204 g protein, 272 g carbs, and 91 g fat per day.
How to Use This Macro Calculator
- Enter your age. Metabolism slows slightly with age, so an accurate age keeps the estimate honest.
- Select your gender. The Mifflin-St Jeor equation uses different constants for men and women.
- Enter your weight in kilograms or pounds using the unit toggle.
- Enter your height in centimeters, or switch to feet and inches.
- Choose your activity level. Be honest here: most people overestimate. If you train 3 days a week and sit the rest, pick moderately active at most.
- Pick your goal: lose, maintain, or gain weight.
- Choose a macro split. Start with Balanced (30/40/30), try High Protein (40/30/30) if you train hard, or Low Carb (25/20/55) if you prefer higher fat meals. You can also type custom percentages as long as they total 100.
- Press Calculate My Macros and use your gram targets to plan meals or log food for the week.
Verified Example Results
Every example below was calculated with this tool and double checked by hand:
| Profile | BMR | TDEE | Target | Protein | Carbs | Fat |
|---|---|---|---|---|---|---|
| Male, 35, 80 kg, 180 cm, moderate, maintain, Balanced 30/40/30 | 1,755 | 2,720 | 2,720 | 204 g | 272 g | 91 g |
| Female, 30, 70 kg, 165 cm, light, lose, High Protein 40/30/30 | 1,420 | 1,953 | 1,453 | 145 g | 109 g | 48 g |
Frequently Asked Questions
What is the best macro split for beginners?
Start with a balanced split of 30% protein, 40% carbs, and 30% fat. It supplies enough protein to protect muscle, enough carbs to fuel daily activity, and enough fat for hormone health. Adjust toward higher protein once tracking feels easy.
How many grams of protein should I eat per day?
Active adults generally do well with 0.7 to 1.0 grams of protein per pound of body weight (about 1.6 to 2.2 g per kg). The calculator’s High Protein preset lands most people in this range automatically.
Are macro calculators accurate?
They are accurate estimates, not lab measurements. The Mifflin-St Jeor equation predicts BMR within about 10% for most people. Track your weight for 2 to 3 weeks: if it moves as expected, your numbers are right; if not, adjust the target by 100 to 200 calories.
Should I count macros or just calories to lose weight?
Counting calories alone can work, but adding macros helps you keep protein high so the weight you lose comes from fat rather than muscle. People who hit protein targets typically look and feel better at the same scale weight.
Can I use this calculator for keto or low carb diets?
Yes. Choose the Low Carb preset (25% protein, 20% carbs, 55% fat) or type a custom split. For strict keto, most people do best keeping carbs under 50 grams per day, which you can set with the custom fields.
How often should I recalculate my macros?
Recalculate whenever your weight changes by about 10 pounds, your activity level shifts, or your goal changes. Your TDEE changes as your body changes, so your targets should too.
Learn More
Ready to put your numbers to work? These guides go deeper: