Macro calculator
Turn a daily calorie figure into grams of protein, carbohydrate and fat. This macro calculator takes the calories you already use, or estimates them from sex, age, height, weight and activity with the Mifflin-St Jeor equation, applies a split you choose (balanced, higher protein, lower carb, keto or your own percentages) and checks it against the Acceptable Macronutrient Distribution Ranges. Free, no sign-up, and nothing you type is stored.
| Macro | Per day | 3 meals | 4 meals | 5 meals |
|---|---|---|---|---|
| Protein | — | — | — | — |
| Carbs | — | — | — | — |
| Fat | — | — | — | — |
| Split | Protein | Carbs | Fat | AMDR |
|---|---|---|---|---|
| Balanced 25 / 45 / 30 | — | — | — | — |
| Higher protein 35 / 45 / 20 | — | — | — | — |
| Lower carb 30 / 35 / 35 | — | — | — | — |
| Keto 25 / 5 / 70 | — | — | — | — |
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Values recalculate instantly as you type. Nothing is sent or stored — the math runs in your browser.
How the calculation works
Everything starts from calories. In “Calculate them for me” mode the calculator estimates your basal metabolic rate with the Mifflin-St Jeor equation, multiplies it by an activity factor for your maintenance calories and applies your goal on top; in “I know my calories” mode it uses your figure as typed. The split then divides those calories by percentage, and grams follow from the energy each macronutrient carries.
Mifflin-St Jeor (1990, the most accurate for the general population):
Men: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Women: (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Activity factors: × 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active, 1.9 very active. These are the conventional multipliers, a convention rather than a measurement.
Goal: −250 or −500 kcal/day to lose fat, +250 or +500 to gain. The target is never taken below 1,200 kcal (women) or 1,500 kcal (men).
Grams = calories × share ÷ 4 for protein and carbohydrate, ÷ 9 for fat (the Atwater general factors: 4, 4 and 9 kcal per gram). Per meal = daily grams ÷ 3, 4 or 5.
The Acceptable Macronutrient Distribution Ranges of the Dietary Reference Intakes are 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat for adults. The Balanced and Higher protein presets sit inside them; Lower carb and Keto do not, and the calculator says so next to the result, as it does for any custom split. Being outside the AMDR is not automatically wrong, ketogenic diets are prescribed for some conditions, but it is a choice to make knowingly.
The protein floor
A percentage can hide a low protein intake at low calories: 25% of 1,200 kcal is 75 g. Check the grams against body weight, which the calculator does when it knows your weight: the RDA is 0.8 g per kg (56 g at 70 kg); the ISSN position stand puts 1.4–2.0 g/kg for exercising people building or keeping muscle; the PROT-AGE group recommends 1.0–1.2 g/kg for healthy adults over 65. Our protein guide works those ranges through by body weight.
IIFYM and the presets
“If it fits your macros” (IIFYM) is the practice of eating whatever you like as long as the daily totals land on target, and this page is the calculator that IIFYM needs. The presets are starting points: Balanced (25/45/30) mirrors the maintenance split of our calorie calculator; Higher protein (35/45/20) puts protein at the top of the AMDR for a cut or a lean bulk; Lower carb (30/35/35) and Keto (25/5/70) are for people who have already chosen those diets. Custom takes any three numbers that add up to 100.
Sources: Mifflin MD, St Jeor ST, Hill LA, et al., A new predictive equation for resting energy expenditure in healthy individuals, Am J Clin Nutr 1990;51(2):241–7. AMDR: National Academies, Dietary Reference Intakes summary tables, Acceptable Macronutrient Distribution Ranges. Energy per gram: FAO, Food energy: methods of analysis and conversion factors, chapter 3 (Atwater general factors, 4.0 kcal/g for protein and carbohydrate, 9.0 kcal/g for fat). Protein: DRI RDA table (0.8 g/kg); Jäger R, Kerksick CM, Campbell BI, et al., International Society of Sports Nutrition Position Stand: protein and exercise, JISSN 2017; Bauer J, Biolo G, Cederholm T, et al., PROT-AGE position paper, JAMDA 2013, the same references as our protein guide. Thermic effect: Westerterp KR, Diet induced thermogenesis, Nutr Metab 2004. The activity multipliers are the conventional 1.2 / 1.375 / 1.55 / 1.725 / 1.9 factors. All retrieved 6 September 2026.
Limits of the estimate
The calories are a statistical estimate: Mifflin-St Jeor is a population equation, body composition and metabolic adaptation move the real number, and the activity multiplier is a convention. The split is a choice, not a prescription: no percentage is right for everyone, and the same grams can come from very different foods. The calculator is not valid during pregnancy or breastfeeding, for people under 18, for elite athletes or with metabolic or kidney conditions, where a healthcare professional should set the numbers. The way to check yours is to log meals for two or three weeks and compare with how your weight actually moves.
Frequently asked questions
How do I calculate my macros?
Start from your daily calories, either a figure you already use or one estimated from sex, age, height, weight and activity with the Mifflin-St Jeor equation. Then split those calories by percentage and convert to grams: protein and carbohydrate carry 4 kcal per gram, fat 9. At 2,000 kcal and a 25/45/30 split that is 125 g of protein, 225 g of carbs and 67 g of fat.
What is the 40-40-20 rule for macros?
A split of 40% of calories from carbohydrate, 40% from protein and 20% from fat, popular in bodybuilding. At 2,000 kcal it gives 200 g of carbs, 200 g of protein and 44 g of fat. Its protein share sits above the Acceptable Macronutrient Distribution Range of 10–35% and its carbohydrate share below the 45–65% range, so it is a training-specific choice rather than a general guideline.
Which macro calculator is most accurate?
None can be more accurate than its calorie estimate, and every calorie formula is a population average. Mifflin-St Jeor, used here, is the equation most calculators rely on, but the honest test is two or three weeks of logging: if your weight moves as expected, the calories are right and the split is a matter of preference and adherence; if not, adjust the calories, not the ratio.
What is the best macro formula for weight loss?
The deficit does the work; the split decides what you keep. The ISSN position stand notes that higher protein intakes help resistance-trained people retain lean mass while eating below maintenance, so a cut usually raises the protein share, keeps fat moderate and gives carbohydrate the rest. In this calculator that is the Higher protein preset (35/45/20) applied to a deficit of 250 to 500 kcal a day.
Can I eat anything as long as I hit my macros?
That is the IIFYM idea, “if it fits your macros”, and for calories and body weight it largely holds: the totals decide the energy balance. Macros say nothing about fibre, vitamins, minerals or how full you feel, though, and 200 g of carbohydrate from oats and 200 g from sweets are the same on this page but not on your plate. Treat the numbers as a budget, not a menu.
What are keto macros?
A ketogenic diet keeps carbohydrate very low, about 5% of calories, with 70–75% from fat and 20–25% from protein. At 2,000 kcal the Keto preset (25/5/70) gives 125 g of protein, 25 g of carbs and 156 g of fat. Its carbohydrate and fat shares fall outside the Acceptable Macronutrient Distribution Ranges, which is why the calculator labels it; discuss it with a professional if you have a medical condition.
Which macro burns the most calories?
Protein. Digesting and storing food costs energy, and a review of diet-induced thermogenesis puts that cost at 20–30% of the calories eaten for protein, 5–10% for carbohydrate and 0–3% for fat. Over a 2,000 kcal day a higher-protein split therefore burns a few dozen kcal more than a low-protein one, a real but small effect next to the deficit itself.
Keep reading
Macro tracking for beginners · How to track macros without measuring · How many grams of protein a day? · Daily calorie calculator · Protein calculator
Now hit the numbers
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