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Macro Calculator

Calculate your daily protein, fat, and carbohydrate targets based on your goal and preferred diet style. Built on the Mifflin-St Jeor TDEE and the ISSN protein recommendations.

Macro calculator inputs

This calculator is for informational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before making changes to your diet, exercise, or health regimen.

What are macros and why do they matter?

Macronutrients — protein, fat, and carbohydrates — are the three substances in food that provide energy. Every calorie you eat comes from one of them (or from alcohol, which most people ignore for diet planning). Where a simple calorie target only answers the question "how much?", a macro target answers "how much of what?" — and that second question determines body composition, recovery, training performance, appetite, and how you feel day to day.

Two diets with the same calories can produce wildly different results. Eating 2,200 kcal with 180 g of protein while lifting weights three times a week adds muscle and holds fat steady; eating the same 2,200 kcal with 60 g of protein and a lot of refined carbs loses muscle and stores fat. The calorie total is identical; the macro split drives the outcome.

How this calculator works

The tool runs in three stages. First, it estimates your TDEE with the Mifflin-St Jeor equation and FAO/WHO/UNU activity multipliers. Second, it adjusts that number based on your goal: cut (−500 kcal), maintain, or bulk (+300 kcal). Third, it splits the resulting calorie target into protein, fat, and carbohydrates according to your chosen diet style:

  • Balanced — 30P / 30F / 40C. Dietitian-friendly default; works for most people.
  • High-protein — 40P / 30F / 30C. Best for lifters, cutters, and anyone trying to preserve or build muscle. Aligns with the upper end of the ISSN protein recommendations (Jäger et al. 2017, JISSN 14:20).
  • Low-carb — 30P / 45F / 25C. For people who feel better on fewer carbs but do not want full ketosis.
  • Keto — 25P / 70F / 5C. Very-low-carbohydrate, high-fat approach used to enter ketosis. Not appropriate for everyone.

Each macro is then converted from calories to grams using 4 kcal/g for protein and carbs and 9 kcal/g for fat.

Worked example

A 28-year-old woman, 62 kg, 168 cm, moderately active (three to five workouts per week), wants to cut on a high-protein split.

  • BMR = (10 × 62) + (6.25 × 168) − (5 × 28) − 161 = 620 + 1,050 − 140 − 161 = 1,369 kcal/day
  • TDEE = 1,369 × 1.55 ≈ 2,122 kcal/day
  • Cut target = 2,122 − 500 ≈ 1,622 kcal/day
  • Protein (40%): 1,622 × 0.40 ÷ 4 ≈ 162 g (about 2.6 g/kg)
  • Fat (30%): 1,622 × 0.30 ÷ 9 ≈ 54 g
  • Carbs (30%): 1,622 × 0.30 ÷ 4 ≈ 122 g

Note how high the protein works out relative to bodyweight during a cut — this is intentional, because protein protects muscle when calories are low. If the same person picked the balanced split instead she would get about 122 g protein (≈2.0 g/kg), 54 g fat, and 162 g carbs.

How to interpret the result

Think of the macro targets as guard rails, not bullseyes. Being within 5 g of protein, 10 g of fat, and 20 g of carbs on any given day is perfectly fine — food labels are accurate to ±20% by law and home measurements have their own noise. What matters is the weekly average.

If your results look strange (e.g. fewer than 40 g of fat, more than 3 g/kg of protein, carbs in the single digits on a non-keto preset) double-check your inputs. Unusual numbers almost always come from extreme activity-level selection, an unrealistic goal, or typing the wrong bodyweight.

Common mistakes

  • Chasing perfection. Hitting 195/59/220 to the gram every single day is neither necessary nor healthy. Aim to land within 5% on protein and 10% on fat/carbs.
  • Forgetting liquid calories. Oils, dressings, coffee creamers, and juice vanish from most food journals. They also break macro budgets fast.
  • Eyeballing protein. A "chicken breast" ranges from 100 g to 300 g. Weigh it once or twice a week to recalibrate your estimates.
  • Under-eating fat on a cut. Going below ~0.5 g/kg of fat can disrupt hormone production. If the calculator gives you 40 g of fat and you feel terrible, shift calories from carbs to fat.
  • Ignoring fibre. Fibre is technically a carbohydrate but behaves metabolically differently. Aim for at least 25 g/day regardless of diet style.
  • Not recalculating. As your weight changes so does your TDEE and therefore your macros. Rerun every 3–4 kg of body-weight change.

When to consult a professional

A macro calculator is a useful self-coaching tool but it cannot replace personalised nutrition guidance. Talk to a registered dietitian or sports nutritionist if you have a chronic medical condition (diabetes, kidney disease, thyroid disease, heart disease), are pregnant or breastfeeding, have a history of disordered eating, are training for a competition, are under 18 or over 65, or follow any therapeutic diet prescribed by a doctor. Professional guidance is especially important for ketogenic diets used for medical reasons, very low-calorie plans, and anyone with food allergies or intolerances that narrow the list of available protein sources.

Frequently Asked Questions

What are macros?
"Macros" is shorthand for macronutrients — the three substances in food that supply calories: protein (4 kcal/g), fat (9 kcal/g), and carbohydrates (4 kcal/g). Alcohol is sometimes called a fourth macro (7 kcal/g) but is not a nutritional requirement. When people talk about "tracking macros" they mean hitting a daily gram target for each of the big three so that their calories come from a specific mix of sources, not just a single calorie number.
Why not just count calories?
Calories tell you if you will lose or gain weight; macros tell you what kind of weight you will lose or gain. The same 2,000 kcal eaten as 50 g of protein versus 150 g of protein produces very different outcomes: the low-protein plan loses more muscle during a deficit and builds less during a surplus. Macros also strongly influence hunger, training performance, and blood sugar stability, so two diets with identical calories can feel completely different.
Which diet style should I pick?
Balanced (30/30/40) is the best default if you have no strong preference and no medical reason to go lower-carb. High-protein (40/30/30) suits people lifting weights or cutting while trying to hold on to muscle. Low-carb (30/45/25) is a compromise for those who feel better on fewer carbs but do not want the strictness of keto. Keto (25/70/5) is for people who want ketosis for medical reasons, appetite control, or specific endurance applications. There is no single "best" — pick the one you can actually eat.
How much protein do I really need?
The International Society of Sports Nutrition position stand recommends 1.4–2.0 g per kg of bodyweight per day for active adults, with up to 2.2 g/kg during a calorie deficit to protect lean mass. Sedentary adults need about 0.8 g/kg (the RDA). Most people under-eat protein rather than overdo it. Our calculator lands on roughly 1.5 g/kg for a balanced diet at maintenance and pushes closer to 2.0 g/kg for high-protein or cutting plans.
Is fat bad?
No — in fact, eating too little fat causes its own problems, including hormonal disruption and poor absorption of fat-soluble vitamins. A sensible floor is around 0.6 g/kg; most people are fine anywhere between that and 1.5 g/kg. The type of fat matters more than the amount for cardiovascular health: favour unsaturated fats from nuts, seeds, olive oil, fatty fish, and avocado, and go easy on ultra-processed sources.
Can I swap carbs for more fat, or vice versa?
Yes. Outside of extreme athletes, the protein target is the most important number and the fat-to-carb ratio can be adjusted to taste. Someone who feels sluggish on low-carb can move carbs up and fat down while keeping calories and protein fixed; someone who prefers fewer carbs can do the opposite. Think of the macro split as a starting point, not a cage.
Do these macros work on keto?
The keto preset (25/70/5) keeps carbs very low, but strict ketogenic dieters often target carbs in grams rather than percentages — typically under 30 g/day. If you are using keto medically, for epilepsy management, or for aggressive ketosis, follow your doctor or dietitian's numbers rather than this calculator's. For general low-carb living, the keto preset is a reasonable ceiling.
Do I need to hit my macros exactly?
Close enough is fine. ±5 g on protein, ±10 g on fat, and ±20 g on carbs is well within the noise of food labels and your own measurement accuracy. What matters is the weekly average, not whether today hit 165 g of protein exactly. Most successful dieters aim for their protein target most tightly and let fat and carbs fluctuate day to day.
Does this work for vegetarians and vegans?
Yes, but plant-based eaters often have to work harder to hit protein targets because plant protein tends to be lower per calorie and less leucine-rich than animal sources. Focus on soy (tofu, tempeh, edamame), seitan, legumes, and high-protein plant-based products. A gram of protein is a gram of protein from a metabolic standpoint, but total daily intake and distribution across meals matter more on a plant-based diet.
Is this a substitute for medical or sports-nutrition advice?
No. This calculator uses population averages and does not account for medical conditions, specific training cycles, body composition goals beyond cut/maintain/bulk, or individual metabolic variation. If you have diabetes, kidney disease, an eating disorder, or are an elite athlete, work with a registered dietitian or sports nutritionist who can tailor macros to your labs, training, and lifestyle.