How to use the macro calculator
- Pick your goal. Losing about 1 lb (0.45 kg) a week takes roughly 500 kcal a day below maintenance; slow muscle gain needs a small surplus of about 250 kcal.
- Enter your body details and activity level. Choose the activity level that matches a normal week, not your best week.
- Choose a protein target in grams per kilogram of body weight, and the share of calories you want from fat. Carbohydrates fill the rest.
The result shows grams per day for each macronutrient, the calories each provides, and a few practical numbers: protein per meal if you eat four times a day, and a fiber target.
How the macros are calculated
1. Calories. Your basal metabolic rate comes from the Mifflin-St Jeor equation (10 × kg + 6.25 × cm − 5 × age, +5 for men or −161 for women), multiplied by an activity factor from 1.2 to 1.9 to get total daily energy expenditure (TDEE), then adjusted for your goal.
2. Protein first. Protein needs scale with body weight, not with calories, so it is set in grams per kilogram. The RDA of 0.8 g/kg prevents deficiency in sedentary adults; the International Society of Sports Nutrition’s position stand (Jäger et al., 2017) recommends 1.4–2.0 g/kg for people who exercise, and more protein helps preserve muscle when you eat below maintenance.
3. Fat as a share of calories. The US Dietary Reference Intakes give an acceptable range of 20–35% of calories from fat for adults. Very low fat makes it hard to get essential fatty acids and fat-soluble vitamins.
4. Carbohydrates are the remainder. Whatever calories are left after protein (4 kcal per gram) and fat (9 kcal per gram) come from carbohydrate (4 kcal per gram). The guidance range for carbs is 45–65% of calories; the calculator tells you if your plan falls outside it.
Worked example
A 30-year-old man, 180 cm and 80 kg, moderately active, wants to maintain his weight. BMR = 800 + 1,125 − 150 + 5 = 1,780 kcal, so TDEE = 1,780 × 1.55 = 2,759 kcal. Protein at 1.6 g/kg is 128 g (512 kcal). Fat at 30% is 828 kcal, or 92 g. That leaves 1,419 kcal for carbohydrate: 355 g. His split is 19% protein, 51% carbs and 30% fat. To lose weight he would drop to 2,259 kcal: protein stays 128 g, fat falls to 75 g and carbs to 267 g.
Protein targets at a glance
| Grams per kg | Per lb | For a 70 kg (154 lb) adult | Who it suits |
|---|---|---|---|
| 0.8 | 0.36 | 56 g | Minimum for healthy sedentary adults (RDA) |
| 1.2 | 0.54 | 84 g | Light exercise; often suggested for adults over 65 |
| 1.6 | 0.73 | 112 g | Regular training; the point beyond which extra protein adds little muscle for most people |
| 2.0 | 0.91 | 140 g | Strength training while dieting |
| 2.2 | 1.0 | 154 g | Upper end for lean, highly trained athletes |
Things to keep in mind
- Large bodies: protein per kilogram of total weight overstates needs when body fat is high. Use your goal weight or a healthy weight from the ideal weight calculator instead of your current weight.
- Exercise days: the activity level already includes your training. Don’t add the calories from the calories burned calculator on top unless you chose “sedentary.”
- Adjust with real data: equations are typically off by about ±10% for an individual. Weigh yourself regularly for 2–3 weeks; if the trend doesn’t match your goal, change calories by 100–200 a day, mostly from carbs or fat.
- Health conditions: kidney disease, diabetes, pregnancy and eating disorders all change what is safe. Talk to a doctor or registered dietitian before following any target.
Frequently asked questions
What is the best macro ratio for weight loss?
There is no single best ratio: in trials, diets with the same calories and protein lose similar amounts of weight whether they are lower in carbs or in fat. What matters most is a calorie deficit you can sustain and enough protein (about 1.6–2.0 g/kg) to protect muscle. Pick a fat share that suits how you like to eat.
How much protein do I need to build muscle?
Research reviews find muscle gain from resistance training levels off at about 1.6 g of protein per kg of body weight per day for most people, with up to 2.2 g/kg as a generous upper bound. Spreading it over 3–4 meals of 20–40 g each works well.
Why are my carbs so high?
Carbs fill whatever calories protein and fat don’t cover, so active people with high calorie needs get a lot of them. If you prefer fewer carbs, choose a higher fat share; the calculator will show the new split.
Should I count net carbs or total carbs?
The grams shown are total carbohydrate, including fiber, matching the “Total Carbohydrate” line on US nutrition labels. Fiber provides fewer calories, so tracking total carbs is the simpler, slightly conservative choice.
How do I hit my macros in practice?
Build each meal around a protein source, add vegetables and a carbohydrate portion, and use fats (oils, nuts, cheese) to round out calories. A food-tracking app for a week or two shows where you land; after that most people can estimate well without weighing everything.
Last updated: October 14, 2026