Macro Calculator
Protein, Carbs & Fat
Get your precise daily macros for fat loss, maintenance, or muscle gain — calculated using the Mifflin-St Jeor formula with goal-specific protein, carb, and fat targets. No guesswork.
Calculate Your Daily Macros
Enter your details below. Your protein, carb, and fat targets update in real time as you adjust any input.
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Macro Calculator: Protein, Carbs & Fat
Most diets fail not because people lack willpower, but because they’re guessing. They reduce calories without understanding where those calories come from. They eat “healthy” foods without knowing whether they’re meeting their protein target. They cut carbs without realising that their training performance — and muscle retention — depends on adequate carbohydrate intake. Macros are the solution: a precise, science-backed framework that tells you exactly how much protein, carbohydrate, and fat to eat every day based on your body, your activity level, and your goal. Use the free macro calculator above, then read on to understand exactly what the numbers mean and how to use them.
Quick example: A 70kg woman, age 28, moderately active, aiming for fat loss: Daily target ≈ 1,773 kcal — with 140g protein, 193g carbs, and 49g fat. A 85kg man, age 32, moderately active, building muscle: ≈ 3,221 kcal — with 187g protein, 418g carbs, and 89g fat. Enter your numbers above to get your personalised plan instantly.
What Are Macros?
Macronutrients — “macros” — are the three primary classes of nutrients that provide your body with energy. Every food you eat is made up of varying proportions of these three building blocks, and each plays a distinct physiological role:
Protein (4 kcal per gram)
Protein is the body’s primary structural material — it builds and repairs muscle tissue, produces hormones and enzymes, supports immune function, and is the most satiating of the three macros. On a gram-for-gram basis, it has the highest thermic effect of food (TEF), meaning your body burns approximately 20–30% of protein calories just in the process of digesting it. For anyone training, dieting, or trying to preserve muscle while losing fat, protein is the non-negotiable priority macro.
Carbohydrates (4 kcal per gram)
Carbohydrates are your body’s preferred energy source, particularly for the brain and high-intensity physical activity. Stored as glycogen in the liver and muscles, carbs directly fuel anaerobic exercise (weight training, sprinting, HIIT). Low carb intake impairs training performance, recovery, and hormonal function — which is why chronically cutting carbs too aggressively undermines body composition goals even when weight loss occurs.
Fats (9 kcal per gram)
At 9 kcal per gram, fat is the most calorie-dense macro — and one of the most misunderstood. Dietary fat is essential for hormone production (including testosterone and estrogen), absorption of fat-soluble vitamins (A, D, E, K), brain function, and joint health. Dropping fat intake below 20% of total calories can impair hormonal health and micronutrient absorption. Healthy fat sources include olive oil, avocados, nuts, seeds, and fatty fish.
How to Calculate Macros
The macro calculation used in the protein carb fat calculator above follows a four-step process, starting from your activity level, broadly consistent with the CDC’s baseline physical activity guidelines for adults:
- Calculate BMR (Basal Metabolic Rate) — the calories your body burns at rest using the Mifflin-St Jeor equation.
- Calculate TDEE (Total Daily Energy Expenditure) — BMR × activity multiplier.
- Adjust calories for your goal — deficit for fat loss, surplus for muscle gain.
- Distribute target calories across protein, fat, and carbs using goal-appropriate ratios.
Mifflin-St Jeor Formula:
Male BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Female BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
TDEE = BMR × activity factor (1.2 to 1.9)
Goal-adjusted calories:
Fat loss = TDEE × 0.8 (20% deficit)
Maintenance = TDEE × 1.0
Muscle gain = TDEE × 1.15 (15% surplus)
How the Macro Calculator Formula Works
This calculator measures your daily calorie needs, then splits that total into grams of protein, carbohydrate, and fat. The formula runs in sequence: BMR estimates calories burned at rest, TDEE adjusts that for your activity level, your goal shifts TDEE up or down, and the remaining calories are divided across the three macros using your chosen diet style. The units are always grams for each macro and kilocalories for the totals. Read the calorie target as a starting point to track against, not a number to hit exactly every day. The formula assumes your entered activity level accurately reflects your typical week, the single largest source of error in the whole calculation; overestimating how active you are inflates every number that follows.
Identify the inputs
You enter sex, age, weight, height, activity level, a goal (fat loss, maintain, or muscle gain), and a diet style (balanced, high protein, low carb, or keto).
Apply the formula
BMR comes from Mifflin-St Jeor. TDEE = BMR × activity factor. Calorie target = TDEE × 0.8, 1.0, or 1.15 depending on your goal. Protein is set at a fixed grams-per-kg rate for your goal, fat as a percentage for your diet style, and carbs fill whatever calories remain.
Perform the calculation
Using the calculator’s default example, a 30-year-old man at 70kg and 170cm, moderately active, fat loss goal: BMR = 700 + 1,062.5 − 150 + 5 = 1,617.5 kcal (shown as 1,618 after rounding). TDEE = 1,617.5 × 1.55 ≈ 2,507 kcal. Target = 2,507 × 0.8 ≈ 2,004 kcal.
Interpret the result
2,004 kcal splits into 140g protein, 235g carbs, and 56g fat for this example. Protein comes first (weight × 2.0g/kg for fat loss), fat is set as a percentage of the total, and carbs absorb whatever calories are left over.
Macro Ratios Explained
Once you have your calorie target, the calories are distributed across the three macros. The right ratio depends on your goal and diet preference:
| Diet style | Protein | Carbs | Fat |
|---|---|---|---|
| Balanced | 25–30% | 40–50% | 20–30% |
| High protein | 35–40% | 35–40% | 20–25% |
| Low carb | 30–35% | 20–25% | 40–45% |
| Keto-style | 25–30% | 5–10% | 60–70% |
| IIFYM (flexible) | 30% | 40% | 30% |
The 40/40/20 Split
One of the most cited macro ratios is 40% protein, 40% carbohydrates, and 20% fat. This high-protein, moderate-carb approach is popular in the fitness community and works well for both fat loss and muscle building. However, “best” is relative to the individual — a 40% protein target on a 2,000 kcal diet means 200g of protein, which may exceed what’s necessary for someone not engaging in heavy resistance training. The macro calculator above calculates protein based on body weight (grams per kg), which is more precise than a fixed percentage.
Best Macros for Weight Loss
The fundamental driver of fat loss is a calorie deficit — consuming fewer calories than you expend. However, the macro composition within that deficit profoundly affects whether you lose primarily fat or whether you also lose significant muscle mass (which slows metabolism and undermines long-term results).
Research consistently shows that high-protein diets produce superior body composition outcomes during calorie restriction compared to lower-protein diets at the same calorie level. Higher protein: preserves lean muscle mass, increases satiety (reducing hunger and cravings), raises the thermic effect of food (you burn slightly more digesting it), and prevents the metabolic adaptations that make weight regain so common.
| Body weight | Protein target (fat loss) | Daily protein goal |
|---|---|---|
| 55 kg (121 lbs) | 1.8–2.2g per kg | 99–121g |
| 70 kg (154 lbs) | 1.8–2.2g per kg | 126–154g |
| 85 kg (187 lbs) | 1.8–2.2g per kg | 153–187g |
| 100 kg (220 lbs) | 1.8–2.2g per kg | 180–220g |
Best Macros for Muscle Gain
Building muscle requires two things: a calorie surplus (more calories than you burn) and sufficient protein to support muscle protein synthesis. Carbohydrates are also critical for muscle gain — they replenish muscle glycogen depleted during training, fuel workouts at high intensity, and trigger an insulin response that is anabolic (muscle-building).
For muscle gain, the daily macro calculator above applies a 10–20% calorie surplus over TDEE, with protein at 1.8–2.4g per kg bodyweight, fat at 20–25% of calories, and carbohydrates filling the remainder. On a 2,800 kcal plan for an 85kg male, that might be 187g protein, 370g carbs, and 71g fat.
The “lean bulk” approach: A moderate surplus of 10–15% above TDEE maximises muscle gain while minimising fat accumulation. Aggressive surpluses (20%+) accelerate fat gain without proportionally increasing the rate of muscle synthesis, since muscle protein synthesis has a ceiling. For most natural trainees, a lean bulk is the optimal long-term approach.
Protein Intake Guide
Of all the macro targets, protein is the most important to get right — and the macro most people consistently under-eat. The general population eating guideline for protein (the RDA) is 0.8g per kg bodyweight — but this is the minimum to prevent deficiency, not the optimal amount for anyone engaged in exercise or body composition goals.
| Population / goal | Protein recommendation | Notes |
|---|---|---|
| Sedentary adults | 0.8g/kg | RDA — prevents deficiency only |
| Recreational gym-goer | 1.4–1.6g/kg | Supports recovery and adaptation |
| Fat loss (calorie deficit) | 1.8–2.2g/kg | Preserves muscle during deficit |
| Muscle building | 1.8–2.4g/kg | Supports maximum MPS |
| Older adults (50+) | 1.6–2.0g/kg | Combats age-related muscle loss |
| Competitive athletes | 2.0–2.4g/kg | High training volume demands |
Practical protein sources to hit your target: chicken breast (31g/100g cooked), tuna (30g/can), Greek yoghurt (10–17g/100g), eggs (6–7g each), cottage cheese (11g/100g), whey protein (20–25g/scoop), lentils (9g/100g cooked), tofu (8–14g/100g).
3 Real-Life Examples
Example 1: 70kg Female — Fat Loss
Profile: 28F, 70kg, 165cm, moderately active (1.55×), fat loss goal, balanced dietBMR: (10×70) + (6.25×165) − (5×28) − 161 = 700 + 1,031 − 140 − 161 = 1,430 kcal
TDEE: 1,430 × 1.55 = 2,217 kcal
Fat loss target: 2,217 × 0.80 = 1,773 kcal
Protein: 70 × 2.0 = 140g → 560 kcal (32%)
Fat: 1,773 × 0.25 / 9 = 49g → 441 kcal (25%)
Carbs: (1,773 − 560 − 441) / 4 = 193g → 772 kcal (44%)
Example 2: 85kg Male — Muscle Gain
Profile: 32M, 85kg, 178cm, very active (1.725×), muscle gain goal, high protein dietBMR: (10×85) + (6.25×178) − (5×32) + 5 = 850 + 1,112 − 160 + 5 = 1,808 kcal
TDEE: 1,808 × 1.725 = 3,118 kcal
Muscle gain target: 3,118 × 1.15 = 3,584 kcal
Protein: 85 × 2.2 = 187g → 748 kcal (21%)
Fat: 3,584 × 0.22 / 9 = 88g → 792 kcal (22%)
Carbs: (3,584 − 748 − 792) / 4 = 511g → 2,044 kcal (57%)
Example 3: 90kg Male, Maintenance
Profile: 45M, 90kg, 180cm, lightly active (1.375×), maintain weight goal, low carb dietBMR: (10×90) + (6.25×180) − (5×45) + 5 = 900 + 1,125 − 225 + 5 = 1,805 kcal
TDEE (maintenance target): 1,805 × 1.375 = 2,482 kcal
Protein: 90 × 1.8 = 162g → 648 kcal (26%)
Fat: 2,482 × 0.42 / 9 = 116g → 1,044 kcal (42%)
Carbs: (2,482 − 648 − 1,044) / 4 = 197g → 788 kcal (32%)
Note: the calculator’s displayed daily total is 2,480 kcal, the sum of the rounded macro grams, a couple of kilocalories below the raw 2,482 kcal TDEE figure due to gram-level rounding.
Common Macro Mistakes
Under-eating protein
The most common mistake. Eating 80–100g of protein when you need 160g means significant muscle loss during a deficit. Protein preserves your metabolism and physique during dieting.
Dropping fat too low
Fat below 15–20% of calories impairs hormone production, particularly testosterone and estrogen. This tanks energy, mood, libido, and recovery. Don’t go below 0.5g/kg bodyweight in fat.
Too aggressive a deficit
Deficits beyond 25–30% significantly increase muscle loss, hormonal adaptation, and the likelihood of metabolic slowdown. A 15–20% deficit is optimal for fat loss with muscle preservation.
Not updating macros as weight changes
As you lose weight, your TDEE decreases. Macros calculated for 85kg don’t apply when you’re 75kg. Recalculate every 4–6 weeks or whenever you lose 3–5% of body weight.
Tracking inaccurately
Studies show people consistently under-report food intake by 20–40%. Weigh food on a kitchen scale, log everything including oils and sauces, and use a nutrition app for accuracy.
Ignoring training in macro splits
On training days, your carbohydrate needs are higher (glycogen replenishment). On rest days, you can reduce carbs and slightly increase fat. Carb cycling can optimise both fat loss and performance.
Important Notes
What this calculator does and doesn’t cover
This tool applies the Mifflin-St Jeor formula and standard macro-splitting rules to the numbers you enter. A few things worth understanding before relying on the results:
- Activity level is the biggest source of error. Most people overestimate how active they genuinely are, which inflates TDEE and every macro that follows. If your real-world weight trend doesn’t match the plan after 3 to 4 weeks, adjust the calorie target rather than assuming the formula is wrong.
- Protein targets use fixed grams-per-kg rates by goal, not a personalized range. The International Society of Sports Nutrition’s position stand on protein and exercise supports a broader range (1.4 to 2.0g/kg for most active people, higher during a deficit), so the calculator’s fixed rates sit within, but don’t span, the full evidence-based range.
- Carbs always absorb whatever calories are left over after protein and fat are set. This means carb grams shift automatically if you change diet style or goal, even when protein and fat stay conceptually similar.
- Keto mode caps carbs between 20 and 30g regardless of your calorie target, then recalculates fat to fill the remaining calories, which is why keto results don’t follow the same percentage table as the other three diet styles.
- Rounding. Figures are rounded for display, so a manual recalculation may differ by a gram or a few calories.
- Not medical or dietary advice. For personalized guidance, especially with an existing health condition, pregnancy, or a history of disordered eating, consult a registered dietitian or healthcare provider.
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