Figuring out your macros comes down to three steps: estimate how many calories you burn in a day, decide on a goal (lose fat, gain muscle, or maintain), and then split those calories between protein, carbs, and fat. The whole process takes about ten minutes with a calculator, and you can fine-tune from there based on how your body responds.
Step 1: Estimate Your Daily Calories
Before you can divide calories into macros, you need a starting calorie number. That starts with your basal metabolic rate (BMR), the energy your body burns just to keep you alive at rest. The most widely used formula is the Mifflin-St Jeor equation:
- Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
To convert pounds to kilograms, divide by 2.2. To convert inches to centimeters, multiply by 2.54. So a 170-pound, 5’10” man who is 30 years old would calculate: (10 × 77.3) + (6.25 × 177.8) – (5 × 30) + 5, which comes out to roughly 1,734 calories at rest.
Your BMR only covers basic survival. To account for movement, you multiply it by an activity factor to get your total daily energy expenditure (TDEE). Common multipliers range from about 1.4 for sedentary office workers up to 1.9 or higher for people with physically demanding jobs or heavy training schedules. If you exercise three to four times per week, a multiplier around 1.55 is a reasonable starting point. Using the example above, that 30-year-old man would land at roughly 2,688 calories per day.
These formulas are estimates, not exact measurements. They give you a useful starting point, but you’ll likely need to adjust after a few weeks based on what the scale, the mirror, and your energy levels tell you.
Step 2: Adjust Calories for Your Goal
Your TDEE represents maintenance, the number of calories that keeps your weight roughly stable. From there, you adjust based on what you’re trying to do:
- Fat loss: Subtract 300 to 500 calories per day from your TDEE. This creates a moderate deficit that supports steady weight loss of about half a pound to one pound per week without tanking your energy or muscle mass.
- Muscle gain: Add 200 to 300 calories per day above your TDEE. A smaller surplus limits unnecessary fat gain while still providing enough fuel to build tissue.
- Maintenance: Use your TDEE as-is.
Aggressive deficits (800+ calories below TDEE) tend to backfire. They increase muscle loss, spike hunger hormones, and make the diet harder to sustain. A moderate approach works better for nearly everyone.
Step 3: Set Your Protein Target
Protein is the macro most worth getting right because it drives muscle repair, keeps you full, and has the highest thermic effect (your body burns more calories digesting it). The federal RDA is 0.8 grams per kilogram of body weight, or about 0.36 grams per pound, but that number reflects the bare minimum to avoid deficiency, not the amount that optimizes body composition.
For most people who exercise regularly, 0.7 to 1.0 grams per pound of body weight is a more practical range. If you’re in a calorie deficit, aim toward the higher end to protect muscle. If you’re at maintenance or in a surplus, the lower end is usually sufficient. For the 170-pound man in our example, that means 120 to 170 grams of protein per day.
Each gram of protein contains 4 calories. So 150 grams of protein equals 600 calories allocated to protein.
Step 4: Set Your Fat Target
Dietary fat is essential for hormone production, brain function, and absorbing fat-soluble vitamins like A, D, E, and K. The Dietary Guidelines for Americans recommend adults get 20 to 35 percent of total calories from fat. Going below 20 percent for extended periods can interfere with hormone balance, particularly testosterone and estrogen.
A good default for most people is around 25 to 30 percent of total calories. If your adjusted daily target is 2,200 calories, 25 percent would be 550 calories from fat. Since fat contains 9 calories per gram, that works out to about 61 grams of fat per day. People who feel better on higher-fat diets can push toward 35 percent, while those who prefer more carbs can stay closer to 20 percent, as long as they don’t drop below that floor consistently.
Step 5: Fill the Rest With Carbs
Once protein and fat are set, the remaining calories go to carbohydrates. Carbs contain 4 calories per gram, just like protein. The Acceptable Macronutrient Distribution Range for carbohydrates is 45 to 65 percent of total calories for adults, but your actual number will depend on how much you’ve already allocated to protein and fat.
Using our running example: if the 170-pound man eating 2,200 calories per day allocates 600 calories to protein (150g) and 550 calories to fat (61g), that leaves 1,050 calories for carbs, which is about 263 grams. Carbs are the most flexible macro. They fuel high-intensity exercise and replenish glycogen in your muscles, so people who train hard generally benefit from keeping carbs on the higher side. If you’re less active, you can afford to keep them lower.
A Complete Example
Here’s what the full calculation looks like for a 30-year-old woman who weighs 150 pounds (68 kg), stands 5’6″ (167.6 cm), exercises four days per week, and wants to lose fat:
BMR: (10 × 68) + (6.25 × 167.6) – (5 × 30) – 161 = 1,376 calories. Multiply by 1.55 for moderate activity: roughly 2,133 calories at maintenance. Subtract 400 for fat loss: 1,733 calories per day.
Protein at 0.85 g/lb: 128 grams (512 calories). Fat at 28 percent of total: 485 calories, or about 54 grams. Carbs from the remainder: 736 calories, or about 184 grams.
Her daily targets: 128g protein, 54g fat, 184g carbs.
Tracking and Adjusting Over Time
A food tracking app makes hitting your macros far easier than guessing. Weigh your food with a kitchen scale for the first few weeks. Most people are surprised by how far off their estimates are, especially for calorie-dense foods like nuts, oils, and cheese.
After two to three weeks, check your progress. If you’re trying to lose fat and the scale hasn’t moved, you’re likely eating more than you think or your activity multiplier was too generous. Drop your daily target by 100 to 150 calories (usually by reducing carbs or fat slightly) and reassess. If you’re losing weight too quickly (more than 1.5 pounds per week) or feeling drained, add calories back. The initial calculation is a starting line, not a finish line.
You also don’t need to hit your numbers perfectly every day. Hitting within 5 to 10 grams of each target is close enough. What matters is consistency across the week, not perfection at every meal.
A Note on Net Carbs
If you follow a low-carb or keto approach, you may have seen the term “net carbs,” which is total carbohydrates minus fiber and sugar alcohols. The idea is that fiber and sugar alcohols don’t spike blood sugar the way regular carbs do, so they shouldn’t count toward your limit. That logic has some basis, but the FDA doesn’t formally recognize net carbs as a category, and sugar alcohols vary widely in how they affect blood sugar. For most people counting macros, tracking total carbohydrates is simpler and more reliable. If you do track net carbs, prioritize whole foods that are naturally high in fiber rather than using the net carb formula as a way to justify processed snacks.