Figuring out your macros comes down to three steps: estimate how many calories you burn in a day, decide how to split those calories between protein, carbs, and fat, then convert those calorie targets into grams. The whole process takes about five minutes once you understand the logic behind each number.
Step 1: Estimate Your Daily Calories
Before you can split calories into macros, you need a calorie target. The most widely used method starts with the Mifflin-St Jeor equation, which estimates your resting metabolic rate (the calories your body burns just to keep you alive).
For men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
For women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
If you think in pounds and inches, multiply your weight in pounds by 0.45 to get kilograms, and your height in inches by 2.54 to get centimeters. A 35-year-old woman who weighs 150 pounds (68 kg) and stands 5’6″ (167.6 cm) would get: (10 × 68) + (6.25 × 167.6) – (5 × 35) – 161 = roughly 1,392 calories at rest.
That resting number then gets multiplied by an activity factor to reflect how much you actually move during the week:
- Sedentary (desk job, little exercise): multiply by 1.2
- Lightly active (light exercise 1-3 days/week): multiply by 1.375
- Moderately active (moderate exercise 3-5 days/week): multiply by 1.55
- Active (hard exercise 6-7 days/week): multiply by 1.725
- Very active (intense daily training or physical job): multiply by 1.9
Our example woman, if moderately active, would land at about 2,158 calories per day. That’s her maintenance number. To lose fat, she’d subtract 300-500 calories. To gain muscle, she’d add 200-300. Most people overestimate their activity level, so when in doubt, pick one tier lower.
Step 2: Set Your Protein Target First
Protein is the macro worth nailing down first because it has the narrowest useful range and the biggest impact on body composition. Each gram of protein contains 4 calories.
The government’s baseline recommendation is 0.8 grams per kilogram of body weight (about 0.36 grams per pound), but that’s the minimum to avoid deficiency, not an optimal target for someone trying to change their body. Research supports eating 1.2 to 2.0 grams per kilogram of body weight for better weight loss outcomes and muscle retention. For a 150-pound person (68 kg), that works out to roughly 82-136 grams of protein per day.
Where you land in that range depends on your goal. If you’re mainly trying to lose fat, aim for the higher end, closer to 1.6-2.0 g/kg. Protein helps preserve muscle during a calorie deficit, and it also keeps you fuller for longer. If you’re at maintenance and just want to stay healthy, 1.2-1.6 g/kg is a solid range. Protein also costs your body more energy to digest than the other macros. It raises your metabolic rate by 15-30% during digestion, compared to 5-10% for carbs and 0-3% for fat.
Step 3: Set Your Fat Target
Fat is essential for hormone production, brain function, and absorbing certain vitamins. Each gram of fat contains 9 calories, more than double protein or carbs, so fat grams add up fast. The Dietary Guidelines for Americans recommend adults get 20-35% of their total calories from fat. Going below 20% for extended periods can interfere with hormonal health, especially in women.
A good starting point for most people is 25-30% of total calories from fat. Using our example of 2,158 maintenance calories, 25% would be about 540 calories from fat, or 60 grams. At 30%, that’s 648 calories, or 72 grams.
Step 4: Fill the Rest With Carbs
Once protein and fat are set, the remaining calories go to carbohydrates. Carbs also contain 4 calories per gram, same as protein. The recommended range for adults is 45-65% of total calories, and in most macro setups, carbs naturally fall somewhere in that window once protein and fat are accounted for.
Here’s the math for our example person at maintenance (2,158 calories), using 120 grams of protein and 65 grams of fat:
- Protein: 120 g × 4 = 480 calories
- Fat: 65 g × 9 = 585 calories
- Remaining for carbs: 2,158 – 480 – 585 = 1,093 calories ÷ 4 = 273 grams of carbs
If you’re highly active, you’ll likely need more carbs. Sports nutrition guidelines recommend 5-7 grams of carbs per kilogram of body weight for moderate-to-high intensity exercise lasting about an hour a day, and 6-10 g/kg for endurance training of 1-3 hours daily. Someone doing light activity or skill-based sports like golf can get by with 3-5 g/kg.
A Practical Example Start to Finish
Let’s walk through the entire process for a 30-year-old man who weighs 180 pounds (82 kg), stands 5’10” (178 cm), exercises moderately 4 days a week, and wants to lose fat.
Resting metabolic rate: (10 × 82) + (6.25 × 178) – (5 × 30) + 5 = 1,788 calories. Multiply by 1.55 for moderate activity: about 2,771 calories at maintenance. Subtract 400 for fat loss: 2,371 calories per day.
Protein at 1.8 g/kg: 82 × 1.8 = 148 grams (592 calories). Fat at 25% of total: 2,371 × 0.25 = 593 calories, or about 66 grams. Remaining carbs: 2,371 – 592 – 593 = 1,186 calories ÷ 4 = 296 grams.
His daily macro targets: 148 g protein, 66 g fat, 296 g carbs. That’s a concrete, trackable plan.
Adjusting Macros for Different Goals
There’s no single perfect macro ratio. The most important factor for weight loss is being in a calorie deficit, and the most important factor for muscle gain is a calorie surplus paired with adequate protein and progressive resistance training. The ratio of carbs to fat within those calorie targets is more flexible than most people think.
That said, some general patterns work well. For fat loss, keeping protein high (1.6-2.0 g/kg) and fat moderate (20-30% of calories) gives you enough carbs to fuel workouts without feeling drained. For muscle gain, protein stays in a similar range, but you have more total calories to work with, so carbs can go higher to support training performance. Some people prefer higher fat and lower carbs for satiety. Others feel sluggish without enough carbs. Personal preference matters here, and the best approach is the one you can actually sustain.
Tracking and Fine-Tuning
Your calculated macros are a starting point, not a final answer. The formulas estimate your calorie needs based on population averages, and individual metabolisms vary. Track your food for two to three weeks, weigh yourself under consistent conditions (same time of day, same state of hydration), and watch the trend.
If you’re trying to lose weight and the scale isn’t budging after two weeks, cut 100-200 calories, primarily from carbs or fat while keeping protein steady. If you’re trying to gain and not seeing progress, add 100-200 calories to carbs. Small adjustments beat dramatic overhauls.
You don’t need to hit your targets to the gram every day. Consistently landing within 5-10 grams of your protein and fat targets, with carbs filling in around them, is precise enough to see results over weeks and months. If tracking every meal feels overwhelming, start by just tracking protein. That single habit gets most people 80% of the way there.
Net Carbs vs. Total Carbs
If you’re following a lower-carb approach, you may see “net carbs” on food labels or in tracking apps. Net carbs equal total carbohydrates minus fiber and sugar alcohols. Both fiber and sugar alcohols pass through your system without significantly raising blood sugar, so they’re subtracted from the total. A food with 24 grams of total carbs but 10 grams of fiber and 8 grams of sugar alcohols would have just 6 net carbs. For most people tracking standard macros, total carbs are fine to use. Net carbs become more relevant if you’re specifically managing blood sugar or following a ketogenic diet.